Self-administered questionnaire and direct observation by checklist: comparing two methods for physical exposure surveillance in a highly repetitive tasks plant.

BACKGROUND: We evaluated the agreement between a questionnaire and an observational checklist for exposure assessment in the setting of an upper-limb work-related musculoskeletal disorders (UWMSD) surveillance program in a population with a high level of physical exposures. METHODS: A surveillance program was implemented in a large shoe factory. Physical exposures were assessed in 1996 by a self-administered questionnaire and by the direct observation of work tasks assessed using a checklist filled out by trained assessors. Items were summed into a "questionnaire" score and an "observational" score. These scores were compared by Pearson's correlation. The association between exposure assessment by each method and UWMSD incidence between 1996 and 1997, defined by a standardized examination, was also studied. RESULTS: Correlation between the "questionnaire" score and the "observational" score was low among the 196 workers (77%) who received both evaluations (rho=0.06, p>0.05). Only exposure assessed by the questionnaire method was significantly associated with high incidence of UWMSD between 1996 and 1997, with good sensitivity (97%) and poor specificity (27%). CONCLUSION: In this surveillance program, self-reported physical exposures assessed by questionnaire and by direct observation did not evaluate same dimensions of high physical exposures. In this sample, exposures assessed by questionnaire identified workers at high risk of incident UWMSD more precisely than exposures identified by direct observation.

Predictive factors for incident musculoskeletal disorders in an in-plant surveillance program.

OBJECTIVES: A surveillance program for upper-limb work-related musculoskeletal disorders (UWMSD) based on assessment of health and risk factors was implemented between 1996 and 2000 in a large shoe factory with overall high levels for biomechanical exposure. The study aimed to identify workers with an increased risk of UWMSD incidence. METHODS: In 1996, 1997 and 2000, 166 workers filled out a questionnaire and underwent a standardized physical examination. Factors from the 1996 questionnaire (general, personal and occupational factors) associated with UWMSD incidence in 1997 were selected. The predictive role of these variables was studied with a logistic model, taking into account also gender and age. The performance of a risk score based on this model was studied in 2000, using the Wilcoxon test and ROC curves. RESULTS: In 1997, 28 incident cases of UWMSD were observed (N = 107, 26.2%). Work pace and prior history of UWMSD were the only factors significantly associated with UWMSD incidence in 1997 (respectively 33% versus 13%, P = 0.02 and 58% versus 22%, P = 0.01). Psychological distress (36% versus 21%, P = 0.10), physical fatigue (35% versus 22%, P = 0.14), repetitiveness (30% versus 18%, P = 0.17) and task precision (33% versus 21%, P = 0.16) were also included in the logistic model for 1997 UWMSD incidence. Controlling for these variables, prior history of UWMSD remained associated with incidence in 1997 (OR = 5.5, 95% CI = 1.4-21.8). In the period from 1997 to 2000, 24 incident cases were observed (N = 102, 23.5%). The risk score, based on variables from the 1997 model, was significantly higher for incident cases (median = 6 in incident cases versus 4.5 for healthy subjects, P = 0.02). ROC curves indicated that the highest agreement reached 67% for sensitivity and 59% for specificity. Among subjects who did not change their task (N = 71, 18 incident cases), performance reached 66% for specificity with the same sensitivity. CONCLUSION: These results suggest that surveillance programs of UWMSD at a company level are possible even with overall high levels for biomechanical exposure and should take into account occupational and personal factors, including prior history of UWMSD.

Surveillance program of neck and upper limb musculoskeletal disorders: assessment over a 4 year period in a large company.

OBJECTIVE: A company-wide surveillance program for musculoskeletal disorders (MSDs) based on the assessment of health and risk factors was implemented between 1996 and 2000 in a large shoe factory. The study aimed to compare the results of the surveillance program in 1996 and 1997 with the occurrence of MSDs in 2000. METHODS: A health and ergonomic assessment of workstations was performed for 253 workers in 1996. Of these, 166 were examined again in both 1997 and 2000. A set of criteria was used to predict whether or not a job category could be predicted to have a potentially high risk of MSDs in 1996 and 1997 and the results were compared with the incidence rate of MSDs in the job category in 2000. RESULTS: The criteria based on prevalence data in 1996 were unable to detect the job categories characterized by the occurrence of MSDs in 2000. The criterion based on an incidence rate >1% in 1997 was sensitive and specific. The agreement between the ranking of the job categories according to incidence rate of MSDs in 1997 and 2000 was good (rho=0.57, P=0.11). Agreement of the prediction based on ergonomic exposure was lower than that based on incidence data. CONCLUSION: The efficacy of the surveillance program to predict on a collective basis the job categories in which numerous cases of MSDs occurred in 2000 depended on the decision criteria used. The criteria based on the incidence of MSDs were more reliable to predict the risk of MSDs than those based on prevalence data or on exposure assessment. Because exposure assessment plays a greater role in determining the priorities for ergonomic intervention, surveillance of health and exposure must nevertheless be combined to predict the risk of MSDs in the plant in the short and middle terms.