Our data indicates that one in three members of the working population of the Federal Republic of Germany (34.4%) experiences back pain within a 7-day period. The 1-year prevalence is 60% for the entire working population. Table starts by presenting occupational groups with a lower-than-average prevalence of subjective back pain (7-day prevalence <34.4%). For instance, only one out of six engineers (16%) and one out of five physicians (19%) reported experiencing back pain within 7 days of taking part in the study (Table ). Closer analysis shows that professionals and managers are highly represented among occupational groups with a low risk of back pain (engineers, physicians, pharmacists, entrepreneurs, managers, marketing experts, ministers, information technology experts, actors, musicians, teachers, and university lecturers). These occupations are professions belonging to the tertiary sector which the German Census Bureau classifies as technical and service occupations (occupational codes 60-93). Some occupations belonging to the secondary sector (manufacturing/construction occupations) also display below-average back pain prevalence. Artisans and production workers are typical members of manufacturing/construction occupations, which bear the occupational codes 10-59 in German labour statistics. It can be seen that the manufacturing/construction occupations featuring in Table rarely involve moving heavy weights (Table ). Examples include inspectors, crane drivers, florists, laboratory technicians, electricians and technicians.
Employed persons with below-average back pain prevalence by occupation (own figures calculated from First National Health Survey data)
In contrast, moving, carrying and lifting heavy weights, and/or a stooped posture are more commonly represented in the occupations associated with an above-average back pain prevalence (bricklayers, concrete masons, foremen, printers, plumbers, pipefitters, steamfitters, assembly workers) shown in Table (7-day prevalence ≥34.4%). Above-average pain prevalences were also reported amongst persons employed in the services sector. In contrast to the occupational groups with third-level qualifications (Table ), the service employees in Table tend to be engaged in more menial tasks (warehouse workers, furniture movers, postal service mail carriers, cleaners, waiters/waitresses, casual labourers, geriatric nurses). These are also occupations typically involving unphysiological postures and/or moving patients or heavy objects.
Employed persons with an above-average back pain prevalence by occupation (own figures calculated from First National Health Survey data)
In addition to providing occupational statistics, this cross-sectional study also permits a more in-depth exploration of specific work-related stress factors and hierarchical rank. While the sample sizes for individual occupation groups are too low to permit gender-matched stratification of the data, the qualitative aspects of labour focused on in the following facilitate the performance of separate analyses for males and females. Our data indicates that 43% of those in full-time or part-time employment are females. Women displayed significantly (P<0.05) higher levels both in terms of 7-day prevalence (38 vs 32%) and 1-year prevalence (62 vs 58%). Social differences are clearly shown in the analysis of the socioeconomic status which is a composite score made up of income, education and occupation (Fig. ).
Back pain prevalence for the Federal Republic of Germany by socioeconomic status and gender (own figures calculated from First National Health Survey data, n=3,488)
Finally, the implications of known work-related risk factors for back pain were studied. This analysis shows that physically strenuous work in a one-sided physical posture and carrying heavy weights are associated with a significantly higher risk of self-reported back pain (Tables , ). Employed persons not exposed to these strains are much less likely to report back pain. This is reflected in a 12% point difference among males (Table ) and a 13% point difference among females (Table ). Environmental factors (noise, air pollution through dust, gases and fumes) and mental stress at work seem to correlate with self-reported back pain in both genders (Tables , ). In contrast, night work, shift work and long working hours do not correlate with a higher risk of back pain. Multiple logistic regression analysis was then used to test whether the work-related strains identified as relevant act per se or whether their impact can be seen to change if the relevant confounders are held constant.
Prevalence of self-reported back pain for male German working population by workplace stress factors in % and resultant pain risk (odds ratio); own figures calculated from First National Health Survey data, n=1,997
Prevalence of self-reported back pain for female German working population by workplace stress factors in % and resultant pain risk (odds ratio); own figures calculated from First National Health Survey data, n=1,491
The situation for male employees is as follows: It was shown for the male population that the risk factors shown to be significant in bivariate analysis remained in force (Table , Model 1). Even with lifestyle differences and age structures controlled for, the odds ratio for male respondents with exposure to heavy loads is 1.45, or 45% higher than that of other employed persons with an odds ratio of 1.00 by definition (Table , Model 2). Unfavourable environmental factors increase the risk of developing back pain by another 26%, and mental stress increases the risk by an additional 37% (Table , Model 2).
In contrast, the only morbidity-relevant factor among the female population is heavy manual labour (Table , Model 2: odds ratio: 1.50). More extensive analysis of the same dataset shows that overweight, depression and family situation seem to play a role as confounders in the aetiology of back pain among females while these variables are of no relevance in men.