Inequalities in zoster disease burden: a population-based cohort study to identify social determinants using linked data from the UK Clinical Practice Research Datalink

Abstract

Background

Zoster vaccination was introduced in England in 2013, where tackling health inequalities is a statutory requirement. However, specific population groups with higher zoster burden remain largely unidentified.

Objective

To evaluate health inequalities in zoster disease burden prior to zoster vaccine introduction in England.

Methods

This population-based cohort study utilised anonymised UK primary care data linked to hospitalisation and deprivation data. Individuals aged ≥65 years without prior zoster history (N=862,470) were followed from 01/09/2003-31/08/2013. Poisson regression was used to obtain adjusted rate ratios (ARR) for the association of socio-demographic factors (ethnicity, immigration status, individuals' area-level deprivation, care home residence, living arrangements) with first zoster episode. Possible mediation by co-morbidities and immunosuppressive medications was also assessed.

Results

There were 37,014 first zoster episodes, with incidence of 8.79 (95% confidence interval (CI):8.70-8.88) per 1,000 person-years at risk. In multivariable analyses, factors associated with higher zoster rates included care home residence (10% higher versus those not in care homes), being female (16% higher versus males), non-immigrants (~30% higher than immigrants) and White ethnicity (for example, twice the rate compared to those of Black ethnicity). Zoster incidence decreased slightly with increasing deprivation (ARR most versus least deprived=0.96 (95%CI:0.92-0.99) and among those living alone (ARR 0.96 (95%CI:0.94-0.98). Mediating variables made little difference to the ARR of social factors but were themselves associated with increased zoster burden (ARR varied from 1.11-3.84).

Conclusions

The burden of zoster was higher in specific socio-demographic groups. Further study is needed to ascertain whether these individuals are attending for zoster vaccination.

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