Int. J. Environ. Res. Public Health2021, 18, 9171 2of 15 due to sickness and early retirement, cost of medical care, low productivity, and personal suffering [12]. These disorders represent one of the greatest work-related challenges of our time, and they have a great impact on individuals and society. Various physical/biomechanical (e.g., repetitive hand motion), psychosocial (e.g., decision latitude at work), organizational (e.g., night shifts), and genetic (e.g., gender) factors have been linked to the development of WMSDs in numerous occupational settings and specific industries [13–15]. Studies to date have only been able to consider some of these factors simultaneously, making it difficult to build a closed picture of the interactions between them [16]. The aim of this analysis was to investigate the association between the presence of upper extremity WMSDs in a healthy working population and different clinical endpoints that are likely to be measured in the clinical routine. Usually, these endpoints only represent more or less useful surrogates for an actual health problem, whose roles should be more clearly determined in order to improve the efficiency of the research. This analysis is also intended to investigate a set of potentially predisposing socio-demographic, work-related, and individual characteristics (“risk factors” or “predictors”) for WMSDs and related clinical endpoints. 2. Materials and Methods 2.1. Study Population The study was conducted at the headquarters and main production site of Aesculap AG, Tuttlingen, Germany, with about 3500 workers and employees. This company is the world market leader in the field of surgical instruments. The study population was divided into three groups based on their occupational activities: group I = grinding and polishing, characterized by repetitive and forceful exertions (“grinding”), group II = inspection and packaging, characterized by repetitive exertions without force (“packaging”), and group III = all other white-collar and blue-collar employees as a cross-section of the company without exposure to grinding or packaging as a control group (“control”). Approval of the study was obtained from the Ethics Committee of the Baden-Wuerttemberg Medical Association, Jahnstrasse 40, 70597 Stuttgart, Germany (project number F-2017-005). 2.2. Study Design and Data Collection Random samples of active white-collar and blue-collar workers were drawn from the three groups using statistic software and were recruited between September 2017 and March 2018. No incentives were offered, and participation decision was met voluntarily on invitation by signing the informed consent. The following eligibility criteria were applied according to our previous publication [17]: Age < 18 or > 65 years; employment in the respective workplace for less than 5 years; currently not on sick leave; no absence from work due to upper extremity pain for more than 2 weeks within the last 3 months; and none of the following conditions: cervical spine syndrome or herniated intervertebral disc, shoulder pain radiating into the forearm, debilitating congenital malformation of the upper extremity, rheumatoid conditions including fibromyalgia, previous upper extremity surgery due to nerve entrapment syndrome(s), and/or chronic musculoskeletal disorders, such as tennis elbow; golfer’s elbow; or tenosynovitis of the flexor and/or extensor tendons, including trigger finger and de Quervain’s disease, and three or less unanswered items in the DASH disability/symptom questionnaire. The participants were asked to fill in two standardized, self-administered questionnaires. The first questionnaire obtained demographic and personal data, considered as predictors in the analyses, such as sex, handedness, secondary occupation, sporting and physical hobbies, age, height and weight (body mass index), employment level, and years of service. Participants completed the questionnaires at the company’s health center independently and without assistance.
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