Social and diagnostic inequality in health

Aims: Empirical studies of social inequalities in health commonly take the diagnosing of disease for granted. Social inequalities in health are seen as the result of social processes, yet the diagnosis itself is rarely considered to contribute to such inequality. We argue that the influence of sociocultural and cognitive bias in the diagnosing process follows a social pattern, such that certain diagnoses are disproportionally over- or underrepresented in different socioeconomic groups due to interpretive bias of underlying symptoms. Methods: Norwegian data on sick leave for diffuse musculoskeletal and diffuse psychiatric disease in 2006 were analysed to study the distribution of the two diagnoses in different status groups. Socioeconomic status was measured by years of education. Diagnoses and occupational codes were based on national registers; diagnoses in accordance with the International Classification of Primary Care second edition. We compared occupations in technical sectors to occupations in the health sector and the relative number of cases of sick leave controlled for years of education, gender, occupational sector, and diagnosis. Data were analysed by cross-tabulation, ratio of diffuse psychiatric/musculoskeletal diseases, and logistic regression. Results: The ratio of diffuse psychiatric/musculoskeletal diseases increases with education and decreases if the employee works in a technical job. Conclusion: The results challenge the traditional explanation that job features alone can explain the distribution of disease and suggest that a part of the persistent social inequality in health can be caused by the diagnosing process. In order to reach a better understanding of the processes behind the social inequalities in health, the diagnosing process itself should also be studied.