Carpal tunnel syndrome diagnosis in occupational epidemiological studies

Carpal tunnel syndrome among laboratory technicians in relation to personal and ergonomic factors at work

OBJECTIVES

Work-related carpal tunnel syndrome (CTS) has been reported in different occupations, including laboratory technicians, so this study was carried out to determine the prevalence and the associated personal and ergonomic factors for CTS among laboratory technicians.

METHODS

A cross-sectional study was conducted among 279 laboratory technicians at King Fahd Hospital, Saudi Arabia, who filled in a self-administered questionnaire, including questions regarding their demographic criteria, occupational history, job tasks, workplace tools, ergonomic factors at work, and symptoms suggestive of CTS. Physical examinations and electrodiagnostic studies were carried out for those who had symptoms suggestive of CTS to confirm the diagnosis. Univariate and multivariate analysis were performed for both personal and physical factors in association with confirmed CTS among laboratory technicians.

RESULTS

The prevalence of CTS among the laboratory technicians was 9.7% (27/279). The following were the statistically significant risk factors for CTS among them: gender (all cases of CTS were female, P=0.00), arm/hand exertion (OR: 7.96; 95% CI: 1.84-34.33), pipetting (OR: 7.27; 95% CI: 3.15-16.78), repetitive tasks (OR: 4.60; 95% CI: 1.39-15.70), using unadjustable chairs or desks (OR: 3.35; 95% CI: 1.23-9.15), and working with a biosafety cabinet (OR: 2.49; 95% CI: 1.11-5.59). CTS cases had significant longer work duration (17.9 ± 5.6 years) than CTS non-case (11.5 ± 7.4 yeas) with low OR (1.108).

CONCLUSION

This study demonstrates some personal and ergonomic factors associated with CTS among the laboratory technicians, including female gender, arm/hand exertion, pipetting, repetitive tasks, working with a biosafety cabinet, and an unadjusted workstation.

Exposure-response relationships between movements and postures of the wrist and carpal tunnel syndrome among male and female house painters: a retrospective cohort study

OBJECTIVES

To investigate exposure-response relationships between measured movements and postures of the wrist and the incidence of carpal tunnel syndrome (CTS), and any modifications by sex.

METHODS

In 2011, we established a historical cohort of 9364 members of the Painters' Union in Denmark. Self-reported task distributions were obtained by questionnaire (53% responded) and combined with sex-specific task exposure matrices to get individual estimates of exposure intensity, that is, velocity of wrist flexion/extension, mean power frequency (MPF) and non-neutral wrist postures. Exposure duration was assessed from yearly working proportions. Registered first-time hospital discharge CTS diagnoses and CTS surgery were collected as outcomes. The cohort was followed from 1994 to 2010. Log-linear Poisson regression was used.

RESULTS

For CTS diagnoses, the adjusted incidence rate ratios (IRRs) increased with increasing wrist velocity (IRR=1.37 (95% CI 1.10 to 1.71) per °/s) and MPF (IRR=1.53 (95% CI 1.21 to 1.91) per 0.01 Hz). For CTS surgery, the results were similar. The outcomes were not related to non-neutral postures or exposure duration. The adjusted IRRs for women were higher than those for men. There were no multiplicative interaction effects between exposure intensity, exposure duration and sex. However, the absolute incidence rates (IRs) increased at a steeper rate for women than for men, indicating an additive interaction.

CONCLUSIONS

The incidence of CTS increased with increasing velocity of wrist flexion/extension and MPF of wrist movements. The relative increase in incidence rates was the same for women and men, but the absolute incidence rates increased at a steeper rate for women than for men.