Genital warts (GW), 90% of which are caused by human papillomavirus (HPV) types 6 and 11, are the commonest sexually transmitted infection (STI) in Ireland, accounting for 34.1% of STIs reported in 2005.1 2

Of the two HPV vaccines available, only one offers protection against HPV 6 and 11.3

The Irish government plans to introduce HPV vaccination and the decision on which vaccine to use will be determined in part by the relative cost-effectiveness of the vaccines.

There is considerable reported variation in the cost of GW.4^–9 Only two studies used contact time to determine costs, both retrospectively.7 8 No studies have been done in Ireland.

This study was carried out to determine the average cost for a case of GW in the Irish setting using direct medical costs only. It is, to our knowledge, the only published study which estimates the cost of GW by measuring contact time prospectively.

METHODS

The study was performed in five hospitals providing the Genito-Urinary Medicine (GUM) services for a defined mixed urban/rural area in south-west Ireland (population: 982 158, 23.2% of the Irish population).

Data were collected from each clinic for a 3-week period between September and November 2007.

Data collection was via a prepiloted data collection sheet on which the contact time between healthcare professional (doctor and/or nurse) and patient, gender and diagnosis category for each consultation was recorded. Four diagnosis categories were allowed (table 1) which included treatment time if appropriate. If a consultation yielded a diagnosis of “HPV + other STI,” half of the consultation time was assumed to be for GW. No distinction was made between new and returning patients.

The data were transferred into Excel and analysed using Excel and R software.

Confidence intervals were calculated around the estimate of time spent on each GW patient by normal approximation to a Poisson confidence interval.

Annual cost data (€750 000) and the number of incident cases for the year (644–305 (47.4%) male, 339 (52.6%) female) were available only for one GUM clinic which accounts for more than 50% of all patients. Additionally, the average cost of drugs for GW patients was known (€30/patient). The average cost per case by gender was calculated using the contact time data and adding the average drugs cost per GW patient.

The Faculty of Public Health Medicine of Ireland ethically approved the study.

RESULTS

Overall, 862 patients attended, of which 852 had complete data as shown in table 1, which outlines the diagnostic category, gender and contact times.

Of the 217 (25.5%) patients with GW (male 12.1%, female 13.4%), 188 (86.6%) did not have any other STI.

The total contact time for GW was 4092.5 min (3836+513×0.5) accounting for 26.2% of total clinic time, with females (2379 min, 15.2%) using more time than males (1713.5 min, 11.0%).

The GUM clinic with cost data available accounted for 52.6% of the total, and the contact time pattern for this clinic was no different to the other four.

Using the contact time data and the known costs for the clinic, the average annual clinic cost per GW patient was €305 ((€750 000×0.262)/644). Drug costs were a further €30/patient giving a total average cost of €335 per GW patient. A confidence interval around the 26.2% of time spent on GW (25.4% to 27.0%) was generated to account for variation due to sampling over different time periods. These limits provide bounds on the average cost of €335 per GW patient (€326 to €344).

As females used a greater proportion of contact time, the average cost for them was €366, and for males it was €300.

DISCUSSION

The proportion of clinic time spent on GW was 26.2%. The average annual cost per GW case was €366 for females and €300 for males.

By prospectively measuring contact time to attribute clinic costs for GW, a more accurate picture of costs emerges than if done retrospectively. The cost differential between genders may be explained by the increased difficulty in visualising and treating introital GW in women, and the longer time required to prepare for examination.

A larger sample size and a longer time frame for data collection would enhance the results and how they could be generalised nationally. However, our findings are within the range found in other countries, which vary from €250 to €780, reflecting variations in type of service and treatment.4^–9

The findings of this study will allow a more complete consideration of the cost-effectiveness of the various HPV vaccines available.