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: Chen PP, Chen J, Gin T et al. Hong Kong Med J. 2004; 10: 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: Johnson CJ, Croghan E, Crawford J. Journal of Nursing Management. 2003; 11:

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 1 st May - 31 st 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 CharacteristicsTotal 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 data CharacteristicsTotal 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 Yes66 (18.1%)37 (17.9%)29 (18.4%) Belief that resting will reduce harm and enhance their recovery Yes159 (43.5%)91 (44%)68 (43%) * Significant at p<0.05

HRQOL & Psychometrics Scores CharacteristicsTotalWork-injuredNot work-injured HADS mean [SD] Anxiety * Depression * n = [4.82] 11.9 [4.72] n = [4.49] 13 [4.33] n = [4.96] 10.4 [4.85] PCS mean [SD] Rum * Mag * Helpless * n = [3.8] 8.2 [3.31] 7.7 [2.5] n = [3.55] 8.7 [3.1] 18.1 [4.68] n = [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 = [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 = [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 = [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-Work in 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 FactorsMann-Whitney U test-valuep-value Financial support*4.379<0.000* Litigation* * FactorsPearson’s correlation coefficientp-value Age Average pain score Pain duration* * * Significant at p<0.05

Factors Associated with Sick Leave Duration in Work-Injured Patients FactorsPearson’s correlation coefficient p-value HADS anxiety score * * HADS depression score *+0.277<0.000* PCS Rum PCS Mag PCS Helpless SF-36 PF * * SF-36 RP SF-36 BP * * SF-36 GH * * SF-36 VT SF-36 SF * * SF- 36 RE * * SF-36 MH * 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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