Estimation of under-reporting of 3 localisations of work-related musculoskeletal diseases (MSDs) in France

Introduction
In industrial countries, studies suggest under-reporting of occupational diseases, particularly for MSDs. In France, the financial compensation of occupational disease relies on “tables”, based on presumption of causality, which define the necessary and sufficient conditions. Nc-WRDs are all the non compensated diseases from occupational origin, reported or not. They were registered via an epidemiological surveillance system, based on a network of volunteer occupational physicians, in 7 regions in 2007. The aim of this study was to evaluate under-reporting of shoulder, hand-wrist-fingers and lumbar rachis MSDs by using data from the surveillance system of nc-WRD and data of compensated occupational diseases.

Methods
For each localisation, the under-reporting rate (%) was defined as following and analysed by gender, age and economic sectors: Frequency of non reported MSDs corresponding to a compensation system table / (frequency of compensated MSDs + frequency of non compensated MSDs).

Results
The under-reporting rate was higher for lumbar rachis than for the other localisations. The under-reporting rate of MSDs diminished with age for shoulder and hand-wrist-fingers (96% and 86% in <25 yrs to 66% and 66% in 55 yrs and more, respectively). The under-reporting rate for hand-wrist-fingers varied little with economic sectors, it was the highest in “support service activities” in men (77% vs 70-72% in the other sectors).

Discussion
This indicator only allows an approach of under-reporting because external factors other than diagnosis are involved in the process from reporting to compensation. However, this study, for the first time, provided an estimation of under-reporting of 3 localisations of MSDs in France. The under-reporting rate diminution with age showed that the claim is more interesting for an aged subject and when the disease consequences become major. The highest under-reporting rate in the support service activities could be explained by the lack of job security in this sector.