‘The Forgotten Joint Score’Construct Validity and Test-Retest Reliability

Justin Roe, Justin Webb, Lucy SalmonNorth Sydney Orthopaedic & Sports Medicine CentreMater Hospital, Sydney, Australia

Disclosures

• Educational support from• Smith and Nephew• Stryker

• Funding for this study was received from Stryker Inc.

Associate Professor Justin Roe

Introduction

• 51,212 Total Knee Replacements in Australia 2013*

• Results generally good– 10-15% patients dissatisfied **

• Review of outcomes is important• Patient reported outcome measures (PROMS)

• * ANJRR 2014• ** Becker Knee Surg Sports Traumatol Arthrosc 2011, Kim J Arthroplasty 2009

What makes a good outcome score?

• Measure the outcome in question• Reliable• Reproducible• Responsive• Validated

• Easy to administer

Associate Professor Justin Roe

Why a new score?

• Many validated scores currently available– KOOS, WOMAC, IKS, Oxford

• Pain, function and symptoms variables– Excellent improvement in scores

• The Ceiling Effect – Large percentage responses near perfect– Inability to detect further improvement– Up to 20% in WOMAC

Associate Professor Justin Roe

The Forgotten Joint Score

• Newly developed and Validated in German Language

• Patient awareness of TKR

• The ‘Forgotten Joint’ is a successful TKR

Associate Professor Justin Roe

The Forgotten Joint Score (FJS-12)

Methods

• 240 Consecutive TKR patients enrolled• Patients completed KOOS and FJS-12• FJS-12 repeated at 4 weeks

• Test-retest reliability was analysed calculating a Intraclass Correlation Coefficient

• Convergent construct validity was assessed with a Spearman’s coefficient between the FJS-12 score and a normalised WOMAC and KOOS score

Associate Professor Justin Roe

Results

• 147 patients returned all questionnaires• 68 females and 79 males• Mean age 67 years (range 32-89)• Mean time from surgery to completion of first

questionnaire 39 months (range 18-72)• Mean time between questionnaires 6 weeks

(3-15)

Associate Professor Justin Roe

Results

Mean SD Range

FJS-12 Initial 62 29 0-100

Follow-up 60 29 0-100

Normalised WOMAC Pain 90 13 50-100

Stiffness 84 17 38-100

Function 90 11 52-100

Total 90 11 52-100

KOOS Quality of Life 76 18 12-100

Symptom 65 14 4-100

Pain 90 12 56-100

ADL 89 13 35-100

Test Re-test Reliability

Intra Class Correlation 95% Confidence Interval Landis & Koch Classification

Overall Score 0.97 0.95-0.98 Almost Perfect

Individual Questions

Night Symptoms 0.88 0.84-0.92 Almost Perfect

Sitting 0.84 0.77-0.88 Almost Perfect

Walking 0.92 0.89-0.94 Almost Perfect

Bathing 0.88 0.84-0.92 Almost Perfect

Travelling 0.86 0.81-0.90 Almost Perfect

Stairs 0.94 0.92-0.96 Almost Perfect

Walking uneven ground 0.91 0.88-0.94 Almost Perfect

Rising 0.90 0.86-0.93 Almost Perfect

Associate Professor Justin Roe

Correlation of FJS-12 with Normalised WOMAC

• The FJS and the WOMAC demonstrate a positive correlation

• The FJS scores have a larger range than the WOMAC scores

Associate Professor Justin Roe

Correlation of FJS-12 with Normalised WOMAC and KOOS

Forgotten Joint Score

Spearman’s Significance

Normalised WOMAC Pain 0.67 0.001

Stiffness 0.52 0.001

Function 0.66 0.001

Total 0.70 0.001

KOOS Quality of Life 0.63 0.001

Symptom 0.33 0.007

Pain 0.68 0.001

ADL 0.66 0.001

Associate Professor Justin Roe

Distribution of Scores

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 990

5

10 FORGOTTEN JOINT SCORE

Forgotten Score Score/100

% o

f pati

ents

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 990

10

20 NORMALISED WOMAC %

score/100

% o

f pati

ents

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 9905

101520

KOOS SYMPTOM %

score/100

% o

f pati

ents

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 990

10

20

30KOOS QOL %

score/100

% o

f pati

ents

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 990

10

20

30KOOS PAIN %

score/100

% o

f pati

ents

broad distribution

similar distribution, clustered lower

FJS 15% > 95

WOMAC26% > 95

30% perfect scores

Ceiling effect

• WOMAC and KOOS Pain scores demonstrate ceiling effect– Reflects excellent pain relief with TKR

• FJS-12 has much wider score distribution

Associate Professor Justin Roe

Discussion

• FJS-12 similar score distribution to KOOS Symptom score

• FJS-12 - 60• KOOS Symptom -65

• May reflect ongoing symptoms in well functioning pain free TKR

Associate Professor Justin Roe

Summary

• Forgotten Joint Score has near perfect test-retest reliability

• Valid when compared to WOMAC and KOOS

• No Ceiling effect

• 12 question format is quick and easy

• Useful adjunctAssociate Professor Justin Roe

Thank-you for your attention.

See you in Sydney

Associate Professor Justin Roe