Familiarity of general practitioners with Q fever decreases hospitalisation risk

Between 2007 and 2010, the Netherlands experienced large outbreaks of Q fever with over 4000 cases. There were unexplained geographical differences in hospitalisation rates of notified patients. We examined the extent of this geographic variation in Q fever hospitalisation and its potential association with general practitioner (GP) experience with Q fever.

We included Q fever cases notified by GPs in 2008 and 2009 in the affected public health region. We used linear regression to describe trends of hospitalisation over time and tested for statistical differences in hospitalisation between municipalities with the chi-square test. We used the number of previously diagnosed Q fever cases of an individual GP as a proxy for Q fever experience, grouped into four categories of GP experience (1; 2; 3-7 and 8 or more cases). We calculated adjusted odds ratios (OR) using logistic regression, taking into account clustering at the GP level.

The proportion of hospitalised cases was highly variable between municipalities (range 0-56%, p-value < 0.001). The proportion of hospitalised cases decreased monthly by 0.7% (95% confidence interval (CI): 0.03-1.3%). The risk of hospitalisation was lower when GPs had seen eight or more Q fever cases compared with GPs who had seen only one case (OR 0.4 [95% CI: 0.2-0.8]).

Our findings suggest that increased GP experience was associated with a reduction in hospitalisations. This supports the public health initiatives to disseminate epidemiological updates and information regarding diagnostic and therapeutic options for Q fever to GPs to reduce Q fever related hospitalisation.