Sick Leave in Patients with Chronic Pain due to Occupational Injury in an

Employer-Financed Work-Injury Compensation System

Sandy Lee, J Yap, PP Chen

Pain Management Centre, Department of Anaesthesiology & Operating Services,

Alice Ho Miu Ling Nethersole Hospital, Tai Po, Hong Kong

Introduction

• Local surveys reported work-related injury was the most frequent cause of chronic pain: 21-36%

Ng KF, Tsui SL, Chan WS. Clin J of Pain. 2002; 18: 275-81Chen PP, Chen J, Gin T et al. Hong Kong Med J. 2004; 10: 150-55

• Chronic pain and the associated factors may prevent the worker from returning to work

• Long sick leave has adverse impact on individual and social status

Vingard E, Alexanderson, K, Norlund A. 2004; 63: 207-15Johnson CJ, Croghan E, Crawford J. Journal of Nursing Management. 2003; 11: 336-42

Objective

• This study examined issues on– pain– sick leave & – return-to-work

among work-injured patients with chronic pain at a regional pain management centre in Hong Kong

Methodology

• A cross-sectional survey

• All patients attending Outpatient Pain Centre at AHNH

• 1st May - 31st Oct 2007

• Exclusion criteria

• Informed consent

Methodology

• Questionnaire– Demographic profiles & pain data

– Sick leave including the duration and reasons

– Reasons of failure to return to work after injury

– Health related quality of life and psychological evaluation:

• HADS, PCS, SF-36

Statistics

• Frequency: – to measure descriptive data

• Mann-Whitney U test, chi square test: – to evaluate any differences between work-injured chronic pain

patients and those with non-work-related injury: data of demographics, pain, health related QOL and psychological evaluation

• Correlation, Mann-Whitney U test, Kruskal-Wallis test: – to analyse factors affecting the respondents’ sick leave duration

after work injury: data of demographics, pain, health related QOL and psychological evaluation

• All p-value less than 0.05 were considered significant

Result

• 442 invited

• 365 recruited

• 207 work-related-injury causing chronic pain

Demographic profiles

* Significant at p<0.05

Characteristics Total

365 cases

Work-injured

207 cases

Not work-injured

158 cases

Age Mean [SD] 43.9 [11.45] 42.3 [9.3] 45.8 [13.5]

Gender *

Male

Female

171 (46.8%)

194 (53.2%)

110 (53.1%)

97 (46.9%)

61 (38.6%)

97 (61.4%)

Marital status

Single

Married

Separated/ windowed

76 (20.8%)

251 (68.8%)

38 (10.4%)

37 (17.9%)

148 (71.5%)

22 (10.6%)

39 (24.7%)

103 (65.2%)

16 (10.1%)

Financial support

No

Yes

233 (63.8%)

132 (36.2%)

132 (63.8%)

75 (36.2%)

101 (63.9%)

57 (36.1%)

Litigation *

Yes

No

169 (46.3%)

196 (53.7%)

142 (68.6%)

65 (31.4%)

27 (17.1%)

131 (82.9%)

Compensation *

Yes

No

179 (49%)

186 (51%)

152 (72.4%)

55 (26.6%)

74 (17.1%)

131 (82.9%)

Pain dataCharacteristics Total

365 cases

Work-injured

207 cases

Not work-injured

158 cases

Pain Duration *

Month Mean [SD] 54.4 [72.37] 38.6 [44.36] 75.2 [93.45]

Average Pain Score

Mean [SD] 5.89 [1.76] 5.91 [1.6] 5.87 [1.95]

Extend of Pain

Affecting their Work *

Mean score [SD] 7.01 [2.24] 7.38 [2.06] 6.53 [2.44]

Belief that medication or

injection will cure their

persistent pain

Yes 66 (18.1%) 37 (17.9%) 29 (18.4%)

Belief that resting will reduce

harm and enhance their

recovery

Yes 159 (43.5%) 91 (44%) 68 (43%)

* Significant at p<0.05

HRQOL & Psychometrics Scores Characteristics Total Work-injured Not work-injured

HADS mean [SD]

Anxiety *

Depression *

n = 349

12.2 [4.82]

11.9 [4.72]

n = 203

13.2 [4.49]

13 [4.33]

n = 146

10.9 [4.96]

10.4 [4.85]

PCS mean [SD]

Rum *

Mag *

Helpless *

n = 346

11.8 [3.8]

8.2 [3.31]

7.7 [2.5]

n = 202

12.3 [3.55]

8.7 [3.1]

18.1 [4.68]

n = 144

11.2 [40.29]

7.5 [3.48]

16.4 [5.56]

SF-36 Score mean [SD]

Physical functioning *

Role, physical *

Bodily pain *

General health

Vitality

Social functioning *

Role, emotional *

Mental health

n = 300

42.2 [33.1]

7.1 [21.1]

22.4 [15.1]

32.1 [19]

29.8 [18.1]

34.1 [25]

15 [32.1]

41.9 [21.8]

n = 174

37.9 [20.1]

2.16 [10]

20.1 [12.9]

31.4 [19.8]

28.4 [17.2]

29.3 [21.4]

9.4 [25.4]

38.5 [20.1]

n = 126

48.2 [44.83]

13.8 [29.25]

26.6 [17.27]

33 [17.87]

31.7 [19.43]

40.8 [28.08]

22.7 [38.34]

46.4 [23.21]

* Significant at p<0.05

Sick Leave in Work-Injured Patients

• 90.8% had taken or were on sick leave

• Mean [SD] duration of sick leave: – 20 months [12.8]

• Reasons for continuation of sick leave > 6 months:– Belief that their injury had not yet healed– Allow time to reach maximal medical improvement– Consider further or alternative treatment

Failure in Return-to-Workin Work-Injured Patients

• Reasons – Pain-induced disability– Coexisting psychological or mood problem– Fear of pain aggravation or re-injury during

work– Belief that they should not return to work if the

condition had not completely healed

Factors Associated with Sick Leave Duration in Work-Injured Patients

Factors Mann-Whitney U test-value p-value

Financial support* 4.379 <0.000*

Litigation* 2.754 0.006*

Factors Pearson’s correlation coefficient p-value

Age +0.77 0.298

Average pain score +0.117 0.111

Pain duration* +0.246 0.001*

* Significant at p<0.05

Factors Associated with Sick Leave Duration in Work-Injured Patients

Factors Pearson’s correlation coefficient

p-value

HADS anxiety score * +0.145 0.005*

HADS depression score * +0.277 <0.000*

PCS Rum +0.082 0.268

PCS Mag +0.126 0.089

PCS Helpless +0.068 0.362

SF-36 PF * -0.198 0.013*

SF-36 RP -0.106 0.19

SF-36 BP * -0.258 0.001*

SF-36 GH * -0.213 0.008*

SF-36 VT -0.098 0.225

SF-36 SF * -0.192 0.0016*

SF- 36 RE * -0.181 0.024*

SF-36 MH -0.156 0.052

* Significant at p<0.05

Conclusion• Local Chinese patients with chronic pain from work-

related injury attending our pain management centre had long duration of sick leave

• Sick leave duration was associated with perceived physical disability, psychological dysfunction, involvement of social welfare and litigation

• Work-injured chronic pain patients were associated with more unfavourable psychometric scores than in patients with chronic pain without work injury

• Apart from perceived disability and psychosocial dysfunction, expectation of full recovery was common reason for long sick leave and failure in RTW

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