Low varicella-related consultation rate in the Netherlands in primary care data

In the Netherlands, a relatively low varicella disease burden compared to other European countries is observed within routine surveillance. To validate this, we estimated the varicella-related consultation rate using The Integrated Primary Care Information database.

In this retrospective cohort study, varicella patients in 2006-2008 were identified by the International Classification of Primary Care (A72) and free text in the electronic medical records, and manually reviewed to be categorised as 'varicella' or 'probable varicella'. The incidence of GP-consultation, specialist referral, emergency department contact and hospitalisation due to varicella was calculated, standardised to the Dutch population.

We identified 1881 varicella cases (2348 including probable cases), 14 patients were hospitalised. The overall incidence of GP-consultation due to varicella per 100,000 person-years was at least 281 (95%CI 268-294) and when probable cases were also included at maximum 354 (95%CI 340-369). The overall incidence of specialist referral, emergency department contact and hospitalisation per 100,000 person-years was 3.9 (95%CI 2.7-5.6), 2.5 (95%CI 1.5-4.0) and 2.0 (95%CI 1.2-3.4) respectively.

This study confirms the relatively low disease burden due to varicella in the Netherlands. In this study, using primary care data, similar incidences of GP consultation and referral to secondary care due to varicella were found as in routine surveillance. The lower varicella-related consultation rate might be linked to more conservative GP consultation behaviour in the Netherlands, and the relatively young age of infection. This is highly relevant for the decision-making process whether or not to introduce universal childhood varicella vaccination in the Netherlands.