Quantification of Risk Factors for Herpes Zoster: Population Based Case-Control Study

This is a case-controlled study from the UK that aimed to estimate the strength of the association of potential risk factors for herpes zoster, and whether risk-factor association strength differs by age. Data were gathered from the UK Clinical Practice Research Datalink, and participants included 144,959 patients diagnosed with zoster between 2000 and 2011; and 549,338 age-, sex-, and practiced-matched controls. Median age of cases and controls was 62 years. Factors associated with increased risk of zoster, in descending order, were systemic lupus erythematosus (0.3% of cases vs. 0.1% of controls; odds ratio [OR] adjusted for matching factors and immune deficiencies of 1.72; 99% confidence interval [CI] 1.45–2.04), rheumatoid arthritis (2.1% vs.1.5%; OR = 1.46; 99% CI 1.38–1.55), inflammatory bowel disease (1.3% vs. 0.9%; OR = 1.36; 99% CI 1.26–1.46), chronic obstructive pulmonary disease (4.7% vs. 3.7%; OR = 1.32; 99% CI 1.27–1.37), asthma (7.1% vs. 5.8%; OR = 1.21; 99% CI 1.17–1.25), type 1 diabetes (0.3% vs. 0.3%; OR = 1.27; 99% CI 1.07–1.50), depression (4.7% vs. 4.0%; OR = 1.15; 99% CI 1.10–1.20), and chronic kidney disease (6.0% vs. 5.4%; OR = 1.14; 99% CI 1.09–1.18). Type 2 diabetes did not have a significant association with zoster. Inhaled steroids had an OR adjusted for matching factors and other immunosuppressive agents of 1.13 (99% CI 1.08–1.18). Patients in severely immunosuppressive conditions making the herpes zoster vaccine contraindicated, not surprisingly, also largely had the greatest risk of zoster. Disease associations, in descending order of odds ratios, were hematopoietic stem cell transplantation (adjusted OR = 13.46), HIV (OR = 5.07), lymphoma (OR = 3.90), myeloma (OR = 2.16), other immunosuppressive treatment (OR = 1.82), leukemia (OR = 1.78), unspecified cellular immune deficiencies (OR = 1.57), and oral corticosteroids (OR = 1.48). Increased risk for risk factors was proportionally greater in younger age groups. This article highlights that vaccines are contraindicated in disease states associated with highest risk for zoster, indicating a need for alternative risk-reduction strategies in these special populations.