Herpesviruses are a family of common viruses that persist for life after someone has been infected. They tend to reactivate over time. Reactivation of varicella zoster, the virus which causes chickenpox, leads to shingles a condition also known as herpes zoster. Reactivation of herpes simplex virus can cause cold sores or genital ulcers. Many people seek medical care for symptoms caused by reactivation of herpesviruses. Electronic health records (EHRs) may therefore be a useful data source to estimate the prevalence of these conditions. However, EHRs may under-record mild episodes of virus reactivation. Some UK health surveys have estimated the proportion of people of different ages who report ever having experienced clinical symptoms due to herpes zoster and simplex.
We will compare the proportion of people with herpes zoster, cold sores and genital ulcers due to herpes simplex in their GP and hospital records using data from the Clinical Practice Research Datalink linked to Hospital Episode Statistics, with the proportion reporting these conditions in population surveys. We will also explore whether proportions vary by age, sex and other factors such as economic deprivation. This will estimate how valid EHRs are for identifying these health conditions and therefore help to inform the design of future research into herpes zoster and simplex.
The alpha herpesviruses varicella zoster virus and herpes simplex viruses types 1 and 2 are common human pathogens which are responsible for substantial morbidity. After primary infection, these viruses establish lifelong latency, mainly in dorsal root ganglia. Reactivation occurs periodically, particularly at times of immune-suppression and may lead to characteristic signs and symptoms. Varicella zoster virus reactivation, known as herpes zoster, causes a painful, blistering dermatomal rash, while for herpes simplex virus, reactivation includes mucocutaneous manifestations such as cold sores and genital ulcers. These viruses can also give rise to rare complications such as encephalitis, which necessitate medical care.
There have been many EHR-based studies of herpes zoster, with far fewer focussed on herpes simplex. While no validation studies exist, it is likely that herpes zoster is reasonably well-captured in EHRs, with high specificity (due to the characteristic clinical presentation) and relatively high sensitivity (as most people consult). Patterns of consulting may however differ by disease severity and age. It is also likely that herpes simplex reactivation is much less well-recorded in EHRs given its often mild clinical course, which would lead to a large degree of under-ascertainment and potential misclassification of herpes simplex in EHR studies.
In this cross sectional study we aim to validate prevalent diagnoses of herpes zoster, cold sores and genital ulcers due to herpes captured in both primary and secondary care EHRs using CPRD data linked to Hospital Episode Statistics by comparing against self-reported prevalence rates from cross-sectional population surveys (Health Survey for England; National Survey of Sexual Attitudes and Lifestyles) and cohorts (EPIC Norfolk) in similar populations and time periods. We will calculate age- and sex-specific rates as well as age-standardised prevalence rates for comparisons. We will further stratify results by factors such as ethnicity, socioeconomic status, region and calendar time. This will inform the design of future research studies into the risk factors and outcomes of for herpes zoster and simplex episodes as well as the effectiveness of prevention and treatment options.
EHR-recorded prevalence of:
1. Herpes zoster
2. Cold sores
3. Genital herpes
Charlotte Warren-Gash - Chief Investigator - London School of Hygiene & Tropical Medicine ( LSHTM )
Charlotte Warren-Gash - Corresponding Applicant - London School of Hygiene & Tropical Medicine ( LSHTM )
Harriet Forbes - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Judith Breuer - Collaborator - University College London ( UCL )
Liam Smeeth - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Sharon Cadogan - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
HES Admitted Patient Care;Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation