Public health questions on physical disabilities and musculoskeletal conditions : studies using health surveys

For population-based information on physical disability and musculoskeletal conditions health surveys are the most important source of information. In this thesis studies are presented on the methods of the health survey and on public health questions concerning physical disabilities and musculoskeletal conditions. Data were used from a national health survey (the NetHIS, several years, n=±9,000 each year), a general epidemiological study (MORGEN-project 1993-1997, n=22,415) and a disease-specific health survey (DMC ₃ -study 1998, n=3,664).

First, two studies were carried out concerning the methodology of the health survey. It was shown that differences did not exist between respondents to a health mail survey or to a health interview survey, with one exception: persons with only primary school education were underrepresented in the mailed survey compared to the interview survey. In addition it was shown that differences in survey methodology had a substantial effect on prevalence estimates of disability. In particular the exact wording of the questions affected the results (up to differences of 16 percentage points), but also the method of data collection. Written questionnaires gave higher prevalences of disability than personal interviews, up to 11 percentage points. It can be concluded that it does not matter how potential participants are approached, the same persons participated (with the exception of the lowest educational groups), but it does matter how data collection takes place and how the questions are worded.

Second, the public health questions on physical disability and musculoskeletal conditions were focused on prevalences, trends, risk groups and determinants. The observed prevalences of self-reported physical disability (12.5% of population of 16 years and over) and musculoskeletal conditions (up to 75% of population aged 25 years and over) were high, which is the same in other western countries. In the period 1990-1998 the prevalence of physical disability did not change with the exception of the prevalence of disability of mobility which dropped slightly with 0.2 percentage points per year. Of the total prevalence of disability of mobility (20.5%) one-third could be attributed to the six following groups of chronic conditions: musculoskeletal diseases, lung diseases, neurological disorders, heart diseases, diabetes, and cancer. Musculoskeletal disorders account for the major part. Risk groups for physical disabilities were older age groups, women, persons living alone, persons who were divorced or widowed and persons with a low educational level. However, general socio-demographic characteristics could not be used to identify high risk groups for musculoskeletal pain, with the exception of persons who are work disabled and women. There were no differences between the working and the non-working population for the burden of low back problems. Activities characterised by an awkward posture, by the same posture for a long time or by often bending and rotating the trunk contributed significantly to low back pain in the population but physical inactivity did not.

Physical disabilities and musculoskeletal conditions make an important contribution to the burden of public health. These health problems need increasing attention of epidemiological research and public health policy, despite the fact that it concerns less than perfect defined health problems ('questionnaire diseases and conditions') based on less than perfect information sources (the health survey).