Snap-fit assembly and upper limb functional limitations in automotive production workers: a nested case-control study.

OBJECTIVES: The use of snap-fits in car-part assembling has developed into an industrial standard. Cross-sectional evidence indicates, however, that this assembling process might adversely affect workers' upper limb function. The objective of this study was to analyze incident cases of upper limb functional limitations (ULFL) in relation to exposure to snap-fit assembly. METHODS: We performed a nested case-control study within a population of 5139 blue-collar automotive production workers. Cases with ULFL detected during follow-up were matched with controls based on employment duration and investigated on their exposure to snap-fit assembly. By conditional logistic regression, we modeled the risk for ULFL according to person-years of exposure to snap-fit assembly, adjusted for gender and baseline BMI. RESULTS: Overall, 64 ULFL cases were detected during a follow-up of 20610.8 person-years (3.1 cases per 1000 person-years). Cases, matched with an average of 4 controls, had significantly longer exposure duration to snap-fit assembly compared with controls (M = 1.15 person-years, SD = 1.68 person-years vs. M = 0.41 person-years, SD = 1.25 person-years). One person-year of exposure to snap-fit assembly was associated with an approximate 20% risk increase of developing ULFLs (OR 1.23, 95% CI 1.08-1.39). CONCLUSIONS: We confirm an association between accumulated exposure to snap-fits in car-part assembling and upper limb musculoskeletal disorders. Company physicians should thus be vigilant to symptoms of musculoskeletal disorders of the upper limbs in snap-fit assembly and support the development of threshold values for snap-fit insertion forces.

Predictors for half-year outcome of impairment in daily life for back pain patients referred for physiotherapy: a prospective observational study.

BACKGROUND AND OBJECTIVE: From observational studies, there is only sparse information available on the predictors of development of impairment in daily life for patients receiving physiotherapy. Therefore, our aim was to identify factors which predict impairment in daily life for patients with back pain 6 months after receiving physiotherapy. METHODS: We conducted a prospective cohort study with 6-month follow-up. Patients were enrolled for treatment in private physiotherapy practices. Patients with a first physiotherapy referral because of thoracic or low back pain, aged 18 to 65 years were included. Primary outcome impairment was measured utilising the 16-item version of the Musculoskeletal Function Assessment Questionnaire. Therapy was documented on a standardized form. Baseline scores for impairment in daily life, symptom characteristics, sociodemographic and psychosocial factors, physical activity, nicotine consumption, intake of analgesics, comorbidity and delivered primary therapy approach were investigated as possible predictors. Univariate and multiple linear regression analyses were performed. RESULTS: A total of 792 patients participated in the study (59% female, mean age 44.4 (SD 11.4), with 6-month follow-up results available from 391 patients. In univariate analysis 17 variables reached significance. In multiple linear regression identified predictors were: impairment in daily life before therapy, mental disorders, duration of the complaints, self-prognosis on work ability, rheumatoid arthritis, age, form of stress at work and physical activity. The variables explain 34% of variance (adjusted R(2), p<0.001). CONCLUSIONS: With minimal information available from observational studies on the predictors of development of back problems for physiotherapy patients, this study adds new knowledge for forming appropriate referral guidelines. Impairment in daily life before therapy, mental disorder as comorbidity and the duration of the complaints can be named as outstanding factors. The results of this study can be used to facilitate comparison of patient therapy goals with the prognosis in everyday practice.

The impact of shift work induced chronic circadian disruption on IL-6 and TNF-alpha immune responses.

AIM: Sleep disturbances induce proinflammatory immune responses, which might increase cardiovascular disease risk. So far the effects of acute sleep deprivation and chronic sleep illnesses on the immune system have been investigated. The particular impact of shift work induced chronic circadian disruption on specific immune responses has not been addressed so far. METHODS: Pittsburgh-Sleep-Quality-Index (PSQI) questionnaire and blood sampling was performed by 225 shift workers and 137 daytime workers. As possible markers the proinflammatory cytokines IL-6 and TNF-alpha and lymphocyte cell count were investigated. A medical examination was performed and biometrical data including age, gender, height, weight, waist and hip circumference and smoking habits were collected by a structured interview. RESULTS: Shift workers had a significantly higher mean PSQI score than day workers (6.73 vs. 4.66; p < 0.001). Day workers and shift workers had similar serum levels of IL-6 (2.30 vs. 2.67 resp.; p = 0.276), TNF-alpha (5.58 vs. 5.68, resp.; p = 0.841) or lymphocytes count (33.68 vs. 32.99, resp.; p = 0.404). Furthermore there were no differences in cytokine levels (IL-6 p = 0.761; TNF-alpha p = 0.759) or lymphocyte count (p = 0.593) comparing the sleep quality within the cohorts. When this calculation of sleep quality was stratified by shift and day workers irrespective of their sleep quality day workers and shift workers had similar serum levels of IL-6, TNF-alpha or lymphocytes count. Multiple linear regression analysis showed a significant correlation of lymphocytes count and smoking habits. CONCLUSION: Shift work induces chronic sleep debt. Our data reveals that chronic sleep debt might not always lead to an activation of the immune system, as we did not observe differences in lymphocyte count or level of IL-6 or TNF-alpha serum concentration between shift workers and day workers. Therefore chronic sleep restriction might be eased by a long-term compensating immune regulation which (in healthy) protects against an overstimulation of proinflammatory immune mechanisms and moderates metabolic changes, as they are known from short-term sleep deprivation or sleep related breathing disorders.

Correlates shift work with increased risk of gastrointestinal complaints or frequency of gastritis or peptic ulcer in H. pylori-infected shift workers?

AIM: There is an ongoing discussion whether work under shift work conditions enhances the ulcerogenic potential of Helicobacter pylori infections. This may be induced by a disruption of the circadian rhythm. The present study assessed whether there is an association between H. pylori infection and an increased risk of gastrointestinal complaints or frequency of gastritis or peptic ulcer in H. pylori-infected shift workers. METHODS: We analyzed 615 workers divided in shift and daytime. Upper gastrointestinal diseases, medication or operation, unspecific gastrointestinal complaints, smoking habits, subjective job strain and private stress factors were monitored. The H. pylori status was analyzed using IgA and IgG antibody concentration in blood and qualitative ELISA for feces. RESULTS: It was observed that 27.6% of all workers, 34.6% of the shift workers and 16% of daytime workers were Hp positive (P = 0.004). Shift workers reported reflux or pyrosis less frequently than daytime workers. No increased lifetime prevalence for gastritis, ulcus or eradication therapy was found for shift workers. Analysis revealed a weak regression between age and Hp-positive gastritis or upper gastrointestinal complaints, smoking habits were a major confounding factor for ulcus disease. Clinical manifestation of gastritis or ulcus disease did not correlate with shift work or especially shift work including night work. CONCLUSIONS: As a result of the present study, it cannot be confirmed that there is a causal connection between shift work and upper or unspecific gastrointestinal complaints or gastritis or peptic ulcer in dependency of a H. pylori colonization.

Outpatient rehabilitation of workers with musculoskeletal disorders using structured workplace description.

OBJECTIVES: In most industrialized countries musculoskeletal disorders contribute considerably (25%) to illness induced work absence. A special interest to reduce worker absences exists in highly specialized industries such as jet manufacturing, where specific knowledge is hard to replace. We investigated the reduction and sustainability in sick leave days by a workplace oriented outpatient rehabilitation program based on structured information exchange between occupational physicians and therapists. METHODS: Sick leave days reduction and return-to-work-ratios were analysed for 79 male blue collar workers with musculoskeletal disease, who voluntarily participated in an outpatient rehabilitation treatment between 2002 and 2005. During rehabilitation therapy standardized workplace descriptions were given to the therapists and individual return-to-work (rtw) schemes were implemented. Therapy lasted from 3 to 4 weeks followed by workplace reintegration. Off-work-time was calculated from 0 to 6 years before and 0 to 3 years after rehabilitation from insurance and industrial medical reports. RESULTS: A total of 97% of the patients returned to their original job at the workplace, usually directly after the rehabilitation. Average sick leave days per year were reduced from 48.8 +/- 32.8 days before to 34.2 +/- 37.3 days after the rehabilitation. The therapy interrupted an increase in sick leave days over the years stabilizing absence at a low level for at least 2 years. Duration of illness related work absence was the only significant predictor for sick leave reduction (P < 0.05). Other common risk factors for musculoskeletal diseases like smoking or body mass index did not significantly influence the therapeutic effect. CONCLUSIONS: Our results support evidence that information exchange for workplace description and rehabilitation therapist may help to reduce sick leave days and achieve very high rtw-ratio. However it is important to observe the effects of this shared information for longer intervals.