[Metaanalysis for the evaluation of risk factors for carpal tunnel syndrome (CTS) Part I. General factors].

The expert committee of the German Ministry for Labour and Social Affairs suggested carpal tunnel syndrome (CTS) as an "occupational disease". This systematic literature review and metaanalysis was aimed at identifying associated and risk factors for CTS. Part I addresses the general factors and possible concurrent factors of CTS. These results may be helpful in later experts' reviews of the "occupational disease CTS".A systematic literature review was performed by examining papers in PubMed, Cochrane, EMBASE and Web of Science databases that were published on or before February 15th, 2011. A total of 87 studies (27 longitudinal and 60 cross-sectional) were included in this metaanalysis. The PRISMA (preferred reporting items for systematic reviews and metaanalyses) guidelines for performing a metaanalysis were strictly followed. All of the effect sizes were calculated using a random effects model.The CTS prevalence in all studies independent of study type was 10.6 % (95 % CI 7.8-14.2). The crude incidence calculated from the longitudinal studies was 10.4 (95 % CI 8.9-11.9)/1000 person years. Female patients more frequently suffered from CTS [OR = 1.9 (95 % CI 1.6-2.2), p < 0.001]. The prevalence of CTS was correlated with an increase in age. The highest prevalence was observed in middle-aged patients (40 to 60 years old). Other significant CTS-associated factors were overweight or obesity [OR = 1.4 (95 % CI 1.3-1.6), p < 0.001]. CTS more frequently occurred in the dominant hand [OR = 1.8 (95 % CI 1.4-2.3), p < 0.001] and in persons of "non-white race" [OR = 1.6 (95 % CI 1.2-1.9), p < 0.001]. Furthermore, CTS was often associated with numerous other general diseases. Real risk factors (results from longitudinal studies) were the following: female gender [OR = 3.7 (95 % CI 2.6-5.2), p < 0.001], middle age [OR = 2.2 (95 % CI 0.9-4.9), p < 0.001], overweight or obesity [OR = 1.5 (95 % CI 1.1-1.9), p < 0.001], diabetes mellitus [OR = 5.3 (95 % CI 1.6-16.8), p < 0.001], and excessive alcohol abuse [OR = 2.3 (95 % CI 0.7-2.3), p < 0.001].CTS is an extremely frequent disease. Independent of occupational burden, many patients are suffering from this frequent peripheral nervous compressive syndrome. These data will be essential in later experts' reviews of the "occupational disease CTS".