Healthcare Performance Measurement and Reporting for LASIK ... · Version No: 3.4 Healthcare...

Version No: 3.4 Healthcare Performance Measurement &

Report for LASIK surgery

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Ver.Date: 19 May 2011 Protocol No.:HR2010-02

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Report Title: Healthcare Performance Measurement & Reporting for LASIK surgery

services provided by OPTIMAX Malaysia

Protocol number: HR2010-02

Document type: Healthcare Performance Report

Document status: FINAL

Release Date: 19 May 2011

Number of pages: 22

Client Optimax Eye Specialist Centre

Investigators Stephen Chung SH MS.Ophth

Chuah KL FRCOphth

NorAzlina BN MS.Ophth

Yen SS MS.Ophth

Site Coordinator Lim Yee Yin

Daniel Jones

Consultant Lim T.O. FRCP, M.Stat

Statisticians Hoo LP PhD, Lena Yeap MSc

Data management & audit Teo JS MSc



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Contents More analysis

Summary .................................................................................................................................... 3 1.0 Introduction .......................................................................................................................... 5

2.0 Analysis set .......................................................................................................................... 6 4.0 Outcomes of LASIK surgery ............................................................................................... 9 5.0 Performance measurement for LASIK surgery & Risk adjustment model ....................... 11

5.1 Performance measures for LASIK surgery .................................................................... 11 5.2 Risk adjustment .............................................................................................................. 11 5.3 Risk adjusted Performance results ................................................................................. 13

6.0 Conclusion ......................................................................................................................... 16 Appendix .................................................................................................................................. 17

Glossary ............................................................................................................................... 17 List of Abbreviations ........................................................................................................... 18

Tables and Figures

Table 1: Reason for ineligibility ............................................................................................ 6 Table 2a: Reason for exclusion from efficacy analysis set .................................................... 7

Table 2b: Reason for exclusion from safety analysis set ....................................................... 7 Table 3: Baseline characteristics of patients undergoing LASIK surgery ............................. 7 Table 4A: Visual Outcomes of LASIK surgery at 6-month post-op ..................................... 9

Table 4B: Refractive Outcomes of LASIK surgery at 6-month post-op ............................... 9 Table 4C: Safety Outcomes of LASIK surgery ................................................................... 10

Table 5: Outcomes of LASIK surgery by individual surgeons............................................ 10 Figure 1a: Comparative performance of Risk adjusted Visual acuity outcome of LASIK

surgery among 4 surgeons ................................................................................................... 13 Figure 1b: Comparative performance of Risk adjusted Visual acuity outcome of LASIK

surgery among 4 surgeons ................................................................................................... 13

Table 6a: Comparative quarterly performance of Risk adjusted Visual acuity outcome of

LASIK surgery among 4 surgeons. ...................................................................................... 14 Figure 6a: Comparative quarterly performance of Risk adjusted Visual acuity outcome of

LASIK surgery (Uncorrected visual acuity (UCVA) >=6/7.5 at 6 months post-op ) .......... 14 Table 6b: Comparative quarterly performance of Risk adjusted Visual acuity outcome of

LASIK surgery among 4 surgeons. ...................................................................................... 15

Figure 6b: Comparative quarterly performance of Risk adjusted Visual acuity outcome of

LASIK surgery (Uncorrected visual acuity (UCVA) >=6/12 at 6 months post-op ) ........... 15 Table 7: Performance measures for LASIK surgery............................................................ 20 Table 8a: Relationship between Visual outcome of LASIK surgery (Uncorrected visual

acuity (UCVA) >=6/7.5 at 6 months post-op) and various putative prognostic factors ...... 21

Table 8b: Relationship between Visual outcome of LASIK surgery (Uncorrected visual

acuity (UCVA) >=6/12 at 6 months post-op) and various putative prognostic factors ....... 22



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Summary

Introduction

We measure the performance of LASIK surgery services provided by Optimax Eye Specialist

Centre. The surgical service was provided by 4 surgeons at its TTDI branch.

Three performance measures were selected:

1. Post-operative Uncorrected visual acuity. This is the acuteness or clearness of vision as

measured using standard vision chart that is achieved after surgery. This is a measure of

visual outcome, a standard measure of treatment effectiveness.

2. Post-operative refraction within +0.5 Diopters of target refraction. This measures the

precision of the refractive correction, a standard measure of refractive outcome of LASIK

surgery

3. Worsening of visual acuity. While the intended effect of LASIK surgery is to improve the

patient’s visual acuity by correcting the refractive error, complications or other

unintended effects of surgery could result in worsening of visual acuity. This is therefore

an important measure of patient safety

Data & Model

For purpose of performance measurement, data were available from 932 patients who have

had 1620 LASIK surgical procedures among them (most patients have had surgery for both

eyes) for correction of myopia between January and December 2010.

For efficacy analysis, data from 287 procedures on 167 patients were excluded from analysis

for the following reasons:

Without post-op visual acuity data at all (57 procedures)

Without post-op visual acuity data at 1 week post op for INTRALASIK, LASIK and

LASIK-XP surgeries (33 procedures)

Without post-op visual acuity data at 3-month post op for LASEK and Epi-LASIK

surgeries (195 procedures)

Too few procedures performed by single doctor (2 procedures)

For safety analysis, data from a further 7 procedures were excluded for lack of BCVA data.

Performance results were risk adjusted using a statistical model that included 4 patients’

factors that affect the visual outcome of surgery. These are age, sex, degree of myopia and

astigmatism.

Results

All surgeons achieved excellent results in 2010:

The mean success rate (defined as UCVA at 6-month post-op 6/7.5 or better) among the 4

surgeons was 95%, and 99% for UCVA 6/12 or better.

Their risk adjusted success rate varies from 93% to 97% ; all 95% confidence intervals

overlap 100% success rate. For UCVA 6/12 or better, all surgeons uniformly achieved

99% risk adjusted success rate.

Their success rates were also consistent, without significant variation in outcomes from

quarter to quarter throughout the year 2010.

The overall on-target refractive error correction rate (defined as MRSE at 6 months

within + 0.5D of Target=0) was 91%; for correction of spherical error alone, the on-target

rate was higher at 95%.



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The result of patient safety outcome was also reassuring.

No patient has suffered serious loss of visual acuity as a result of LASIK surgery at 6

months post-op.

All patients had best spectacle corrected visual acuity (BCVA) better than 6/12 at 6

months post-op.

Caution is however warranted in interpreting the performance results reported here.

The analysis was based entirely on retrospective data collected for administrative purpose

rather than specifically for performance measurement. Not surprisingly, there was

substantial data error and extensive data cleaning efforts were required prior to analysis.

Several known prognostic factors (corneal curvature, corneal thickness, pupil size etc)

could be included in the statistical model for risk adjustment. The risk model will require

further development and validation, pending improvement in data quality and availability

of data on known prognostic factors

Both the above issues are being addressed at the prospective phase of this initiative (started

since January 2011) where data required will be defined clearly and data will be collected

prospectively using systematic data reporting mechanisms and subject to ongoing data QC to

assure data quality.

Conclusion

The performance of LASIK surgery services as provided by the Optimax eye care group is

reassuring.

These results also established a sound scientific basis and operational experience for the

Optimax eye healthcare group to embark on routine prospective measurement of the

performance LASIK surgery services. This has been initiated since January 2011.



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1.0 Introduction

Laser-Assisted In-Situ Keratomileusis or LASIK in short, is a surgical technique for the

correction of myopia, hyperopia and astigmatism. It involves the use of excimer laser to

ablate corneal tissue thus reshaping in order to correct the refractive error. LASIK [1,2] has

evolved from a variety of techniques including lamellar keratoplasty, photorefractive

keratectomy, and since the 1990s has been widely used. The technology associated with the

LASIK procedure has also advanced rapidly since then. Recent innovations include new

femtolaser microkeratome, newer laser technology (Faster laser speed, finer laser spots, eye-

tracking system etc), wavefront and topographic custom ablation. Numerous prospective

randomized controlled trials and meta-analyses of these trials have demonstrated the safety

and efficacy of LASIK for the correction of refractive errors [3-11].

Refractive surgery was first introduced into Malaysia by Optimax in 1995. Since then its use

has increased rapidly with the vast majority of the procedures still being performed by

Optimax. Optimax has also grown from a single centre with a lone surgeon to become the

leading provider of LASIK and other specialist eye care services in Malaysia with a network

of 12 centers and 9 ophthalmologists.

Worldwide there is an increasing interest in measuring the performance of healthcare

providers [12,13,14]. The publication of the highly influential report, Performance

Measurement: Accelerating Improvement, by the Institute of Medicine in 2006 [15], has

added greater impetus for performance measurement as a central tenet of health care reform.

Our government has also recently introduced KPI to measure the performance of government

services as part of the Government Transformation Programme [16]. However, this has yet to

impact on the public health services where performance measurement and reporting activity

remains undeveloped. Similarly in the private healthcare sector, while financial performance

measures are well established and routinely reported, robust healthcare performance

measures that reflect the core business of the healthcare industry are practically non-existent.

As a testament to Optimax’s leadership position in the field of LASIK surgery services in

Malaysia, Optimax has agreed to subject its LASIK services to performance measurement

and reporting by an independent third party. This is intended not just to support quality

improvements initiatives within Optimax, but also as a reflection of Optimax’s commitment

to a high standard of accountability in healthcare. To this end, measuring and reporting the

performance of Optimax’s LASIK surgery services is intended to assure healthcare payers

(insurance companies, employers) that they are getting value for their money, to respond to

the requirements of quality certification/ accreditation organizations (ISO9000, JCI) and

regulators (CKAP MOH), and most importantly to aid customers, both patients as well as

health professionals who refer patients, in making informed choices.

This is the first in a series of reports on the performance LASIK surgery by Optimax.



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2.0 Analysis set

Between Jan and December 2010 inclusive, data were available from 953 patients who have

had 1760 LASIK surgical procedures (most patients have had surgery for both eyes) for

correction of myopia performed by 5 surgeons at Optimax’s TTDI centre.

Of these, only 932 patients who have had 1620 procedures were eligible for inclusion in this

analysis for the purpose of performance measurement.

Efficacy analysis set

For efficacy analysis (visual and refractive outcomes), a further 167 patients who have had

287 procedures were excluded from analysis for missing efficacy measure data as follows:

Without post-op visual acuity data at all (57 procedures)

Without post-op visual acuity data at 1 week post op for INTRALASIK, LASIK and

LASIK-XP surgeries (33 procedures)

Without post-op visual acuity data at 3-month post op for LASEK and Epi-LASIK

surgeries (195 procedures)

Safety analysis set

For safety analysis (BCVA outcome), data from 7 procedures were excluded because of

missing BCVA data (These 7 procedures were from 5 patients, but only 2 patients completely

excluded as data for procedures on both eyes were missing)

LASIK surgery on 1760 eyes for

953 patients

Eligible for analysis

1620 eyes from 932 patients

Ineligible

140 eyes, 21 patients

Refer table below for details

Efficacy analysis set


Excluded from Efficacy analysis set

287 eyes, 167 patients


Safety analysis set


Excluded from Safety analysis set

7 eyes, 2 patients


Table 1: Reason for ineligibility

Reason Procedure % Patient %

Both eyes were treated for hypermetropia 26 1 13 1

Sole eye treated for monovision 3 0 3 0

Sole eye treated for hypermetropia 5 0 5 1

One of two eyes treated for hypermetropia or

monovision

106 6 0 0



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Table 2a: Reason for exclusion from efficacy analysis set


No post-op UCVA 285 18 166 18

All 57 4 32 3

1 week post op for INTRALASIK,

LASIK and LASIK-XP

33 2 15 2

3-month post op for LASEK and Epi-

LASIK

195 12 119 13

Too few procedures by a doctor 2 0 1 0

Table 2b: Reason for exclusion from safety analysis set


No post-op BCVA at all 7 1 2 0

3.0 Baseline descriptive analysis

The table below summarizes the patients’ characteristics and LASIK surgery for the 765

patients included in this analysis.

Table 3: Baseline characteristics of patients undergoing LASIK surgery

Patient characteristics Statistics

Number of patients=765

Mean (SD) Age, years 31.46 (7.12)

Sex, No. (%)

Male 263 (34.38)

Female 502 (65.62)

Number of procedures=1333

Prior Refractive surgery, No. (%) No data

Type of LASIK, No. (%)

INTRALASIK 1183 (88.75)

LASIK 44 (3.3)

LASIK XP 35 (2.63)

EPILASIK 65 (4.88)

LASEK 6 (0.45)

Pre-Op Visual Acuity(VA)

No. (%) with manifest Best spectacle Corrected VA (BCVA) >=

6/6 1302 (97.67)

No. (%) with manifest BCVA >= 6/12 1333 (100)

Mean (SD) manifest BC VA (decimal scale) 0.997 (0.0405)

Mean (SD) manifest BCVA (LogMAR scale) 0.0017 (0.0183)

No. (%) with cycloplegic BCVA >= 6/6 1279 (95.95)

No. (%) with cycloplegic BCVA >= 6/12 1333 (100)

Mean (SD) cyclo BCVA (decimal scale) 0.993 (0.0489)

Mean (SD) cyclo BCVA (LogMAR scale) 0.0036 (0.0231)



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Pre-Op Refractive measurements

Spherical Error (SER), Dioptre (D)

Mean (SD) Manifest Spherical Error -4.87 (2.2)

Range(max, min) Manifest Spherical Error (-0.25, -12.5)

Mean (SD) Cycloplegic Spherical Error -4.68 (2.21)

Range(max, min) Cycloplegic Spherical Error (-0.25, -12)

No. (%) with Manifest Spherical Error >=(neg) -6.0 D (Low to

moderate Myopia) 954 (71.57)

No. (%) with Manifest Spherical Error < -6.0 D (Moderate to

High Myopia) 379 (28.43)

No. (%) with Cycloplegic Spherical Error >=(neg) -6.0 D 982 (73.67)

No. (%) with Cycloplegic Spherical Error < (neg)-6.0 D 351 (26.33)

Cylindrical Error (CER), Dioptre (D)

Mean (SD) Manifest Cylindrical Error -0.92 (0.81)

Range (max, min) Manifest Cylindrical Error (0, -5.5)

Mean (SD) Cycloplegic Cylindrical Error -0.92 (0.82)

Range (max, min) Cycloplegic Cylindrical Error (0.25, -5.75)

No. (%) with Manifest Cylindrical Error >= (neg)-2.0 D (Low to

moderate Astigmatism) 1220 (91.52)

No. (%) with Manifest Cylindrical Error < (neg)-2.0 D (Moderate

to High Astigmatism) 113 (8.48)

No. (%) with Cycloplegic Cylindrical Error >= (neg)-2.0 D 1220 (91.52)

No. (%) with Cycloplegic Cylindrical Error < (neg)- 2.0D 113 (8.48)

Spherical Equivalent (SEQ) [SEQ=SER + 0.5 CER], Dioptre (D)

Mean (SD) Manifest Spherical Equivalent -5.33 (2.26)

Range(max, min) Manifest Spherical Equivalent (-0.62, -12.75)

Mean (SD) Cycloplegic Spherical Equivalent -5.14 (2.26)

Range(max, min) Cycloplegic Spherical Equivalent (-0.5, -12.37)

Other Pre-Op/ Intra-op Ophthalmic measurements

Mean (SD) Corneal Curvature (Keratometry) Flat K 43.17

(1.34)

Mean (SD) Corneal Curvature (Keratometry) Steep K 44.48

(1.46)

Mean (SD) Corneal Curvature (Keratometry) Average k

Average k = (Flat K+Steep K)/2

43.83 (1.35)

Flap thickness (Pachymetry), mm No data

Pupil size, mm No data

Refer Appendix for results on Baseline characteristics of patients who had required enhanced

LASIK surgical procedures



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4.0 Outcomes of LASIK surgery

The table below summarizes the outcomes (visual acuity, refractive and safety) of LASIK

treatment for all procedures included in this analysis.

Table 4A: Visual Outcomes of LASIK surgery at 6-month post-op

Visual Outcome Statistics 6-month post-op, N= 1333

UCVA (Fractional scale) Median 6/6

IQR (6/6, 6/6)

Min, Max (6/45, 6/4.5)

UCVA (Decimal scale) Mean 0.96

SD 0.12

UCVA (LogMAR scale) Mean 0.02

SD 0.07

UCVA 6/7.5 or better No. 1262

(%) (94.67)

UCVA 6/12 or better No. 1319

(%) (98.95)

Table 4B: Refractive Outcomes of LASIK surgery at 6-month post-op

Refractive Outcome Statistics 6-month post-op

N= 1333

Manifest Refractive Spherical Equivalent

(MRSE)

Mean (SD) -0.14 (0.3)

Min, Max (-1.5, 1.75)

MRSE within + 0.5D of Target=0 No. (%) 1213 (91)

MRSE < - 0.5D of Target=0 No. (%) 102 (8)

MRSE > + 0.5D of Target=0 No. (%) 18 (1)

Change in Post-op MRSE from Baseline MRSE Mean (SD) 5.19 (2.3)

Min, Max (0.5, 12.75)

Manifest Spherical Error (MSPH) Mean (SD) -0.04 (0.33)

Min, Max (-1.5, 2)

MSPH within + 0.5D of Target=0 No. (%) 1260 (95)

MSPH < - 0.5D of Target=0 No. (%) 36 (3)

MSPH > + 0.5D of Target =0 ie Over-Correction No. (%) 37 (3)

Change in Post-op MSPH from Baseline MSPH Mean (SD) 4.83 (2.27)

Min, Max (0, 13)

Manifest Cylindrical Error (MCYL) Mean (SD) -0.29 (0.25)

Min, Max (-2.5, 0)

MCYL within + 0.5D of Target=0 No. (%) 1233 (93)

MCYL < - 0.5D of Target=0 No. (%) 100 (8)

MCYL > + 0.5D of Target =0 No. (%) 0 (0)

Change in Post-op MCYL from Baseline MCYL Mean (SD) 0.64 (0.78)

Min, Max (-0.75, 4.75)



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Table 4C: Safety Outcomes of LASIK surgery

Safety Outcome Statistics 6-month post-op,

N= 1326

Loss of >= 2 lines of BCVA No. 0 (%) (0)

Final BCVA equal or worst than 6/12 No. 0

(%) (0)

Table 5: Outcomes of LASIK surgery by individual surgeons

Surgeons A B C D

N 381 98 783 71

Outcome measures

Visual outcome

No (%) with UCVA 6/7.5 or better at 3

months 370(97.11) 95(96.94) 727(92.85) 67(94.37)

No (%) with UCVA 6/12 or better at 3

months 379(99.48) 96(97.96) 775(98.98) 70(98.59)

No (%) with UCVA 6/7.5 or better at 6

months 371(97.38) 95(96.94) 730(93.23) 66(92.96)

No (%) with UCVA 6/12 or better at 6

months 377(98.95) 97(98.98) 775(98.98) 70(98.59)

Refractive outcome

No (%) with MRSE at 3 months within +

0.5D of Target=0

355(93.18) 86(87.76) 697(89.02) 64(90.14)

No (%) with MRSE at 6 months within +

0.5D of Targe=0

356(93.44) 87(88.78) 704(89.91) 66(92.96)

Safety outcome

No (%) with Loss of >= 2 lines BSCVA at 3

months

0 (0) 0 (0) 0 (0) 0 (0)

No (%) with Final BSCVA at 3 months

worse than 6/12

0 (0) 0 (0) 0 (0) 0 (0)

No (%) with Loss of >= 2 lines BSCVA at 6

months

0 (0) 0 (0) 0 (0) 0 (0)

No (%) with Final BSCVA at 6 months

worse than 6/12

0 (0) 0 (0) 0 (0) 0 (0)



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5.0 Performance measurement for LASIK surgery & Risk adjustment model

5.1 Performance measures for LASIK surgery

In healthcare, performance measures are those process, structure, efficiency, or outcome

measures that have been developed using rigorous methodology. These measures are

intended not only for clinical quality improvement but they have attributes rendering them

suitable for public reporting, explicit comparisons of care between healthcare providers,

accreditation, pay for performance programs, or other forms of accountability.

For LASIK surgery, we selected three performance measures:

1. Post-operative Uncorrected visual acuity. This is the acuteness or clearness of vision as

measured using standard vision chart that is achieved after surgery. This is a measure of

visual outcome, a standard measure of treatment effectiveness.

2. Post-operative refraction within +0.5 Diopters of target refraction. This measures the

precision of the refractive correction, a standard measure of refractive outcome of LASIK

surgery

3. Worsening of visual acuity. While the intended effect of LASIK surgery is to improve the

patient’s visual acuity by correcting the refractive error, complications or other

unintended effects of surgery could result in worsening of visual acuity. This is therefore

an important measure of patient safety

Details on the selected performance measures are described in the Appendix

5.2 Risk adjustment

Valid measurement of performance also requires statistical methods that account for

differences in patient characteristics (between providers and over time) as well as random

variation arising from small sample size or infrequent outcome event of interest. In other

words, performance results need to be so called risk-adjusted to eliminate the influence of

those elements of the patient population that affect results but are out of the control of the

healthcare providers whose performance are being assessed.

We were unable to identify an established statistical model for the purpose of risk adjustment.

Based on a literature review, we consider the following known prognostic factors for

inclusion in the model development. However, not all factors could be included for reasons

given below too:

# Risk factors Inclusion in risk model.

If not, reason for exclusion

1. Age Included

2. Sex Included

3. Prior refractive surgery No data

4. Pupil size No data

5. Spherical errors or degree of myopia Included

6. Cylindrical errors or degree of astigmatism Included

7. Corneal thickness No data

8. Corneal topography (Steep and Flat K) Included

9. Intra-ocular pressure No data

10. Laser transition zone No data

11. Types of LASIK surgery Some types of surgery have too few records,

hence excluded

For the purpose of risk modeling, we define successful visual outcome is defined as LASIK

surgery that results in a patient attaining uncorrected visual acuity (UCVA) of 6/7.5 or better



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at 6 months post-op. This is justified by the marked variability in the relationship between

measure of refractive error (eg spherical error) and UCVA which can be subjective. The

scatter plot from the data below illustrates this:

0.5

.81

1.5

UC

VA

6 m

ths p

ost-

op

: de

cim

al sca

le

-2 -1 0 1 2MRSE 6 mths post-op

bandwidth = .8

Lowess smoother

Our model building results were as follows:

Age appears to have an effect with the youngest and oldest age groups less likely to have

successful visual outcomes but these did not reach statistical significance.

Female patients have poorer UCVA results. Subsequent investigation showed that this ws

entirely due to systematic bias in measuring females’ UCVA. For a given refractive error,

female reported worst UCVA than male.

The degree of myopia and astigmatism were clearly highly influential, the more severe

the myopia or astigmatism, the worst the outcome, as is well reported in the literature too.

Corneal curvature is expected to be influential. However, patients with high or low

corneal curvature were systematically excluded from treatment by the treating physicians

according to current practice standard. Hence, the range of values found among the

treated patients were too restricted (mean k 43.8, SD 1.35, min. 38.9 and max. 47.9) to

elicit an effect on outcome.

Based on the above findings, the final model to be used for risk adjustment includes only age,

sex, degree of myopia and astigmatism. This will require refinement as more data on more

prognostic factors as well as for more patients become available in future.

Details on the risk modelling are shown in the Appendix



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5.3 Risk adjusted Performance results

We use the risk model developed above to adjust the visual acuity outcome results for the 4

surgeons (anonymized as A, B, C and D) included in this analysis. Results are shown in the

figures below

Figure 1a: Comparative performance of Risk adjusted Visual acuity outcome of LASIK surgery among 4 surgeons

Values are Percent of patients with UCVA >=6/7.5 at 6 months post-op (95% confidence

interval)

Surg-

eons

Risk adjusted

Visual Acuity

outcome (%)

95% CI

A 97.42 (87.51, 100)

AB

CD

Su

rge

on

70 75 80 85 90 94.67 100Adjusted success rate

(lower 95% CI, Upper 95% CI)

B 96.68 (77.24, 100)

C 93.27 (86.50, 100)

D 92.62 (70.27, 100)

All 94.67

Figure 1b: Comparative performance of Risk adjusted Visual acuity outcome of LASIK surgery among 4 surgeons

Values are Percent of patients with UCVA >=6/12 at 6 months post-op (95% confidence

interval)

Sur-

geons

Risk adjusted

Visual Acuity

outcome (%)

95% CI

A 99.00 (79.30, 100)

AB

CD

Su

rge

on

75 80 85 90 95 98.95Adjusted success rate


B 98.97 (92.00, 100)

C 98.95 (88.96, 100)

D 98.68 (75.57, 100)

All 98.95



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Table 6a: Comparative quarterly performance of Risk adjusted Visual acuity outcome of LASIK surgery among 4 surgeons.

Values are Percent of patients with Uncorrected visual acuity (UCVA) >=6/7.5 at 6 months

post-op (95% confidence interval)

Surgeon Q1 Q2 Q3 Q4 Overall

A 100% 100% 97.12% 98.84% 97.42%

(82.04, 100) (82.44, 100) (72.74, 100) (79.75, 100) (87.51, 100)

B 99.96% 93.62% 97.79% 100% 96.68%

(72.25, 100) (42.73, 100) (54.93, 100) (44.9, 100) (77.24, 100)

C 91.25% 92.29% 92.75% 90.79% 93.27%

(76.74, 100) (78.99, 100) (80.49, 100) (77.26, 100) (86.5, 100)

D 93.51% 89.71% 90.22% 88.98% 92.62%

(54.43, 100) (52.22, 100) (41.18, 100) (30.84, 100) (70.27, 100)

Figure 6a: Comparative quarterly performance of Risk adjusted Visual acuity outcome of LASIK surgery (Uncorrected visual acuity (UCVA) >=6/7.5 at 6 months post-op )

70

80

90

97

Adju

ste

d s

uccess r

ate

Q1 Q2 Q3 Q4Period


Quaterly Performance of Doctor A

40

50

60

70

80

97

Adju

ste

d s

uccess r

ate

Q1 Q2 Q3 Q4Period


Quaterly Performance of Doctor B

70

80

93

100

Adju

ste

d s

uccess r

ate

Q1 Q2 Q3 Q4Period


Quaterly Performance of Doctor C

30

40

50

60

70

80

93

Adju

ste

d s

uccess r

ate

Q1 Q2 Q3 Q4Period


Quaterly Performance of Doctor D



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Table 6b: Comparative quarterly performance of Risk adjusted Visual acuity outcome of LASIK surgery among 4 surgeons.

Values are Percent of patients with Uncorrected visual acuity (UCVA) >=6/12 at 6 months

post-op (95% confidence interval)

Surgeon Q1 Q2 Q3 Q4 Overall

A 99.95% 99.92% 95.43% 100% 99%

(72.52, 100) (47.58, 100) (53.6, 100) (43.59, 100) (79.3, 100)

B 99.48% 98.57% 99.51% 98.38% 98.97%

(84.26, 100) (84.73, 100) (86.7, 100) (84.16, 100) (92, 100)

C 99% 99.06% 97.10% 99.93% 98.95%

(79.88, 100) (80.02, 100) (73.12, 100) (81, 100) (88.96, 100)

D 99.81% 99.70% 99.49% 89.98% 98.68%

(59.02, 100) (59.81, 100) (47.37, 100) (31.19, 100) (75.57, 100)

Figure 6b: Comparative quarterly performance of Risk adjusted Visual acuity outcome of LASIK surgery (Uncorrected visual acuity (UCVA) >=6/12 at 6 months post-op )

40

50

60

70

80

90

99

Adju

ste

d s

uccess r

ate

Q1 Q2 Q3 Q4Period


Quaterly Performance of Doctor A

80

85

90

95

99

Adju

ste

d s

uccess r

ate

Q1 Q2 Q3 Q4Period


Quaterly Performance of Doctor B

70

75

80

85

90

95

99

Adju

ste

d s

uccess r

ate

Q1 Q2 Q3 Q4Period


Quaterly Performance of Doctor C

30

40

50

60

70

80

90

99

Adju

ste

d s

uccess r

ate

Q1 Q2 Q3 Q4Period


Quaterly Performance of Doctor D



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6.0 Conclusion

We measure the performance of LASIK surgery services provided by Optimax Eye Specialist

Centre. The surgical service was provided by 4 surgeons at its TTDI branch.

Three performance measures were selected, (1) Post-operative Uncorrected visual acuity. (2)

Post-operative refraction within +0.5 D of target refraction and (3) Worsening of visual

acuity post-op, a measure of patient safety.

The performance results achieved by Optimax in 2010 were excellent.

The mean success rate (defined as UCVA at 6-month post-op 6/7.5 or better) among the 4

surgeons was 95%, and 99% for UCVA 6/12 or better.

Their risk adjusted success rate varies from 93% to 97% ; all 95% confidence intervals

overlap 100% success rate. For UCVA 6/12 or better, all surgeons uniformly achieved

99% risk adjusted success rate.

The on-target refractive error correction rate (defined as MRSE at 6 months within +

0.5D of Target=0) was 91%; for correction of spherical error alone, the on-target rate was

higher at 95%.

The safety record of LASIK surgery as provided by Optimax was excellent. No patient

has suffered any significant loss of visual acuity as a result of LASIK surgery at 6 months

post-op. All patients had a final BCVA better than 6/12 at 6 months post-op.

Caution is however warranted in interpreting and using the performance results reported here.

The results were based on data collected retrospectively and the risk model used requires

further refinement.

These results however have established a sound scientific basis and operational experience

for the Optimax eye healthcare group to embark on routine prospective measurement of the

performance LASIK surgery services. This has been initiated since January 2011.



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Appendix

Glossary

This section defines the various technical terms found in this protocol/ report in simple non-

technical language for the benefits of readers unfamiliar with the subject matter under

investigation.

Accountability The requirement that healthcare providers who have voluntarily

taken on the responsibility to provide healthcare services and are so

accredited or licensed, and to whom the necessary authority and

resources are provided in order for them to discharge their

responsibility, be held answerable for results

Astigmatism One form of refractive error where the focusing power of the eye is

only affected in one meridian than it is in another.

Epi-LASIK The Epi-LASIK procedure employs a unique microkeratome, called

the “Epikeratome”, to mechanically “separate” the epithelium from

the stroma, creating a flap of epithelial cells only (Epi-flap). Unlike

LASIK, no sharp blades or knives are required and unlike LASEK,

no alcohol is required. The Epi-flap is moved aside so that the laser

can reshape the exposed cornea. After laser application, the Epiflap

is replaced over the corneal bed and a bandage soft contact lens is

placed on top at the end of procedure.

Healthcare

providers

Refers to both institutional providers of health care services (e.g.,

clinics, hospitals, nursing homes) and clinicians (e.g., physicians,

nurse practitioners, nurses, physician assistants).

Hyperopia One form of refractive error where the optical power of the eye is

too weak to focus light on the retina. This can arise from a cornea

with too little curvature or an eyeball that is too short

INTRALASIK IntraLASIK is a procedure that similar to LASIK where corneal flap

is created for laser ablation. However in this procedure, flap is

created using femtosecond laser instead of mechanical blade

(microkeratome)

The procedure uses a software to direct the Femtosecond laser to

optically focus its beam into a tiny, 1 micron (.001mm) spot of

energy that passes harmlessly through the outer layers of the cornea

until reaching its exact depth within the stroma (central deeper layer

of the cornea). The laser beam creates a separation plane by forming

an interconnecting series of bubbles made of carbon dioxide and

water vapor.

The laser beam stacks a pattern of bubbles along the periphery of

the treatment plane, leaving a separated section of tissue to act as a

hinge. As with a traditional LASIK approach, the surgeon then folds

the tissue back to expose the underlying corneal layer to prepare for

the excimer laser treatment that will re-shape the cornea. With All-

Laser-Lasik, surgeons can avoid the complications related to

surgical blade problems. The Femtosecond laser precisely delivers

the laser energy directly to the outer surface of the eye, which

suffers no trauma.

LASEK Laser epithelial keratomileusis or LASEK is a modified form of

photorefractive keratectomy (PRK). This procedure requires the



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outer layer of the cornea- epithelium to be loosened with the diluted

alcohol solution for around 30 seconds. Then the loosened

epithelium (Epi-flap) is moved aside so that the laser can reshape

the exposed cornea. After laser application, the Epi-flap is replaced

over the corneal bed and a bandage soft contact lens is placed on top

at the end of procedure.

LASIK Laser-assisted in situ keratomileusis

A surgical procedure for the correction of refractive error.

A circular superficial cornea flap is made initially with a

mircokeratome (a special steel blade). The flap is then folded back

to allow a type of laser (excimer laser) to ablate and reshape the

deeper layers (stroma) of the cornea according to the patient’s

spectacles prescription. Following laser ablation, the flap is

repositioned and will adhere itself naturally without the need for

stitches.

Myopia One form of refractive error in which the focusing power

(refraction) of the eye is too strong such that when viewing distant

object, the image of the viewed object is brought into focus in front

of the retina rather than on it. Myopia can arise from a cornea with

too much curvature or an eyeball that is too long

Performance The activity of a healthcare provider intended to accomplish the

goals of healthcare. These goals are healthcare should be safe,

effective, patient-centered, timely, efficient, and equitable.

Performance

measure

Performance Measures are those measures of process, structure,

efficiency, or outcome that have been developed using rigorous

methodology , and are intended not only for clinical quality

improvement but they have attributes rendering them suitable for

public reporting, explicit comparisons of care between healthcare

providers, accreditation, pay for performance programs, or other

forms of accountability.

Refractive error An error in the focusing of light on the retina (this is back portion of

the eye) and a frequent reason for reduced visual acuity.

Refractive surgery Changing a patient’s optical measurements for the purpose of

correction of refractive error by means of an operation

Risk adjustment A process that modifies the analysis of performance measurement

results by those elements of the patient population that affect

results, are out of the control of providers, and are likely to be

common and

not randomly distributed

Visual acuity Acuteness or clearness of vision. It is often measured according to

the size of letters viewed on a Snellen chart

List of Abbreviations

AvSR Average Success rate

BCVA Best Spectacle Corrected Visual acuity

CDM Clinical Data Management

CER Cylindrical Error

CI Confidence interval

http://en.wikipedia.org/wiki/Keratomileusis



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CKAPS Cawangan Kawalan Amalan Perubatan Swasta MOH

CRA Clinical Research Associate

CRF Case Report Form

CRM Clinical Research Manager

D Dioptre

DBMS Database Management System

EC Ethics Committee

eCRF Electronic CRF

EDC Electronic Data Capture

ESR Expected Success rate

HPG Healthcare provider group

HPMRS Healthcare Performance Measurement & Reporting System

IC Malaysian National Registration Card or otherwise called the Identity Card

ICT Information and Communication Technology

ID Identity

IEC Independent Ethics Committee

IQR Interquartile Range

IRB Institutional Review Board

IT/IS Information Technology and Information System

JCI Joint Commission International

KPI Key Performance Indicator

LASIK Laser-assisted in situ keratomileusis

Max Maximum

Min Minimum

MOH Ministry of Health, Malaysia

MRSE Manifest Refractive Spherical Equivalent

N Number

N/A Not Applicable

N/K Not known

No. Number

OSR Observed Success rate

QA Quality Assurance

QC Quality control

RASR Risk adjusted Success rate

SAP Statistical Analysis Plan

SC Site Coordinator

SD Standard Deviation

SDV Source Document Verification

SE Standard Error

SEQ Spherical Equivalent

SER Spherical Error

TTDI Taman Tun Dr Ismail

UCVA Uncorrected Visual acuity

http://en.wikipedia.org/wiki/Keratomileusis



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Table 7: Performance measures for LASIK surgery

1. Performance measure Post-operative Uncorrected visual acuity

Description & Rationale Acuteness or clearness of vision as measured using a vision

chart. This is the most commonly used measure to evaluate

visual acuity outcome of LASIK surgery services; just as it is

the most well accepted efficacy measure in clinical trial of

LASIK surgery.

Period of care At the time of LASIK surgery and continued throughout the

period of care being assessed

Denominator All patients undergoing LASIK surgery for correction of

myopia at an Optimax centre

Numerator Number of patients with uncorrected visual acuity (UCVA)

6/12 or better at 6 months post-op

Data sources Patient medical record

Operating room record

2. Performance measure Post-operative Refraction within +0.5 Diopters of target

Refraction

Description & Rationale Measure of the precision of the refractive correction

This is the most commonly used measure to evaluate refractive

outcome of LASIK surgery services; just as it is a well accepted

efficacy measure in clinical trial of LASIK surgery.





Numerator Number of patients with mean spherical equivalent within +0.5

Diopers of target refraction at 6 months post-op



3. Performance

measure

Loss of visual acuity

Description & Rationale Visual acuity as measured using a vision chart.

Loss of 2 or more lines post-op is commonly used to evaluate

loss of visual acuity as a measure of patient safety, just as it is

the most well accepted safety measure in clinical trial of

LASIK surgery.





Numerator Number of patients with loss of 2 or more lines of Best

spectacle Corrected Visual Acuity (BCVA) at 6 months post-op





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Table 8a: Relationship between Visual outcome of LASIK surgery (Uncorrected visual acuity (UCVA) >=6/7.5 at 6 months post-op) and various putative prognostic factors

Uni-

variable

analysis

Multi-

variable

Logistic

regression

analysis

(k included)

Multi-

variable

Logistic

regression

analysis

(k excluded)

Factors N Odds Ratio P value Odds Ratio P value Odds Ratio P value

Age in years

< 25 Ref

254 1 - 1 - 1 -

25-29 374 0.68 0.40 0.72 0.49 0.72 0.48

29-34 351 0.56 0.20 0.55 0.21 0.55 0.20

35-39 354 0.29 0.003 0.25 0.002 0.25 0.002

Sex

Male Ref

462 1 - 1 - 1 -

Female 871 0.68 0.15 0.69 0.21 0.68 0.17

Myopia, manifest

Low-

Moderate (<=

6 D) Ref

954 1 - 1 - 1 -

Moderate to

High ( > 6.0

D)

379 0.52 0.01 0.52 0.01 0.52 0.01

Astigmatism,

manifest

Low-

Moderate (<=

2 D) Ref

1220 1 - 1 - 1 -

Moderate to

High ( > 2.0

D)

113 0.48 0.03 0.35 0.004 0.35 0.004

Corneal curvature

Mean K 1333 0.89 0.05 0.96 0.68



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Table 8b: Relationship between Visual outcome of LASIK surgery (Uncorrected visual acuity (UCVA) >=6/12 at 6 months post-op) and various putative prognostic factors

Uni-

variable

analysis

Multi-

variable

Logistic

regression

analysis

(k included)

Multi-

variable

Logistic

regression

analysis

(k excluded)

Factors N Odds Ratio P value Odds Ratio P value Odds Ratio P value

Age in years

< 25 Ref

254 1 - 1 - 1 -

25-29 374 0.98 0.98 1.04 0.96 1.09 0.92

29-34 351 1.38 0.75 1.49 0.69 1.61 0.64

35-39 354 0.39 0.25 0.38 0.24 0.42 0.29

Sex

Male Ref

462 1 - 1 - 1 -

Female 871 0.51 0.31 0.41 0.18 0.47 0.25

Myopia, manifest

Low-

Moderate (<=

6 D) Ref

954 1 - 1 - 1 -

Moderate to

High ( > 6.0

D)

379 0.99 0.99 0.97 0.96 1.03 0.96

Astigmatism,

manifest

Low-

Moderate (<=

2 D) Ref

1220 1 - 1 - 1 -

Moderate to

High ( > 2.0

D)

113 1.21 0.86 0.88 0.91 0.95 0.96

Corneal curvature

Mean K 1333 1.16 0.46 1.25 0.27

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