European study finds wasteful use of post-exposure prophylaxis

Non-occupational post-exposure prophylaxis for HIV (NONOPEP) is being prescribed at widely disparate rates in different European countries and is often prescribed for minimal risks, according to a poster presentation at this week's Fifteenth International AIDS Conference in Bangkok. It estimates that two to three HIV infections, representing an effectiveness of about 50%, were prevented with a total of 1,418 prescriptions of PEP.

The European NONOPEP Registry is a voluntary reporting system by clinics on requests for PEP that they receive and the prescriptions they issue. The poster summarised requests for PEP between January 2001 and June 2004, reported from clinics in France, Spain, Switzerland, Italy, the Netherlands, Germany, Denmark, Ireland, Portugal, Belgium, Greece, the UK and Austria (this list in the order of the number of PEP requests reported per country).

The Registry has widely differing numbers of reporting clinics in different countries, which is one of the reasons it recorded 713 requests for PEP in France during the period but only 19 in the UK. Some countries such as Italy already have a national requirement to report requests for PEP. But it also reflects differences in the popularity of PEP as a prevention tool in different countries. For instance, two of the six UK hospitals reported no requests for non-occupational PEP at all to the Registry during the study period.

Requests for PEP were made 2,239 times by 2,035 individuals. After risk assessment, 1,418 prescriptions were issued (69% of cases).

Men comprised nearly two thirds of cases (63.4%) and the median age of cases was 29, with a range from five months to 90 years, reflecting the variety of different reasons individuals sought PEP. The five month old baby was given PEP after an accidental needlestick scratch by her HIV positive father.

PEP was sought for the following reasons: sexual (62%), needle-borne exposure (27%) and other (11%).

Investigator Juan Almeda of Badalona, Spain told aidsmap.com that although injuries to paramedics in the course of their duties were counted as occupational exposure, injuries to other emergency staff such as police involved in violent arrests were classed as non-occupational.

When it came to risk assessment, 93% of all requests for incidents judged as ‘high risk’ received treatment, 84% of ‘medium risk’ and 36% of ‘low risk’, though the poster did not define the criteria for these categories.

Triple therapy was prescribed 70% of the time, with dual therapy 16% of the time, and quadruple therapy a surprisingly high 12% of the time. Almeda said that the practice in some clinics was to ‘boost’ triple NRTI/PI therapy with a starter dose of nevirapine to ensure rapid drug exposure.

PEP recipients experienced a high incidence of side effects. Over half – 54% - reported nausea, vomiting or diarrhea, 13.7% fatigue or muscle aches, 6.2% headache, 6.2% abdominal pain, and 5.8% developed laboratory abnormalities such as raised liver enzymes.

A quarter (24%) interrupted treatment. In the 13.1% where the cause for this was known, half did so due to side effects and about a quarter each by patient request and because the source tested HIV negative.

Effectiveness of PEP was difficult to judge because follow up rates were low – only a third of those not treated and 24% of those treated were followed up at six months, though three month rates were higher.

There were a total of two known HIV seroconversions among those treated with PEP, both of them gay men infected sexually. Reasons for the failure of PEP were not given.

The investigators calculate that four or possibly five seroconversions, given the different risks involved, would have been expected if the 1,418 treated patients had not been treated, or a rate of 0.35%. The efficacy was therefore not much more than 50%.

The investigators conclude: “Given the frequency of side effects, the costs versus benefits of widely-prescribed NONOPEP should be evaluated.”