People at the highest risk of shingles are those with immunosuppressive conditions (such as HIV) but they are not entitled to vaccination due to safety concerns, suggests a paper published in BMJ today.
Researchers say alternative strategies are needed to reduce the risk of shingles among these patient groups.
Shingles is a common disease among older individuals which causes an acute painful rash and can lead to a complication (called postherpetic neuralgia) resulting in pain lasting from months to years that can significantly impair a person's quality of life.
Researchers from the London School of Hygiene & Tropical Medicine used data from over 144,000 UK adults diagnosed with shingles between 2000 and 2011, and compared this with a group of patients without shingles, to explore whether patients with certain medical conditions may be at increased risk of developing shingles.
The median age at shingles diagnosis was found to be 62 years and around 60% of patients were female.
A number of relatively common conditions were associated with an increased risk of shingles. People with rheumatoid arthritis, chronic obstructive pulmonary disease, or inflammatory bowel disease were 30-50% more likely to have a shingles diagnosis, than individuals without these conditions. Other common medical conditions which were associated with a smaller increase in shingles risk were asthma, chronic kidney disease, type 1 diabetes and depression.
Among those with some of these medical conditions the increased risk of shingles appeared to be greater among younger individuals. But because shingles is less common in younger individuals their absolute risk of developing shingles remains low.
A shingles vaccine is currently available and licensed among individuals aged over 50. Further research would be required to establish whether vaccination is warranted in patients with these medical conditions, particularly those in younger age groups not currently targeted to receive the vaccine; these individuals are less likely to develop long-term pain and complications from shingles.
However the researchers emphasise that those at the highest risk of shingles remain patients with conditions causing severe immunosuppression (such as HIV and leukaemia); for example patients with HIV were five times as likely to develop shingles compared to individuals without HIV. Such patients are currently not eligible for vaccination due to safety concerns. The researchers therefore say this study highlights the need to identify strategies to reduce the risk of shingles among patients with severe immunosuppression.
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Paper: Quantification of risk factors for herpes zoster: population based case-control study, BMJ, 2014.