Molluscum contagiosum and associations with atopic eczema in children: a retrospective longitudinal study in primary care

Jonathan R Olsen, Vincent Piguet, John Gallacher, Nick A Francis

Molluscum contagiosum (MC) is a common skin condition in children. Consultation rates and current management in primary care, and how these have changed over time, are poorly described. An association between the presence of atopic eczema (AE) and MC has been shown, but the subsequent risk of developing MC in children with a diagnosis of AE is not known. To describe the consultation rate and management of MC in general practice in the UK over time, and test the hypothesis that a history of AE increases the risk of developing MC in childhood. Two studies are reported: a retrospective longitudinal study of MC cases and an age-sex matched case-cohort study of AE cases, both datasets being held in the UK Clinical Practice Research Datalink from 2004 to 2013. Data of all recorded MC and AE primary care consultations for children aged 0 to 14 years were collected and two main analyses were conducted using these data: a retrospective longitudinal analysis and an age-sex matched case-cohort analysis. The rate of MC consultations in primary care for children aged 0 to 14 years is 9.5 per 1000 (95% CI = 9.4 to 9.6). The greatest rate of consultations for both sexes is in children aged 1-4 years and 5-9 years (13.1 to 13.0 (males) and 13.0 to 13.9 (females) per 1000 respectively). Consultation rates for MC have declined by 50% from 2004 to 2013. Children were found to be more likely to have an MC consultation if they had previously consulted a GP with AE (OR 1.13; 95% CI = 1.11 to 1.16; P<0.005). Consultations for MC in primary care are common, especially in 1-9-year-olds, but they declined significantly during the decade under study. A primary care diagnosis of AE is associated with an increased risk of a subsequent primary care diagnosis of MC.