Outcomes from switches to atazanavir/r in London

Simon Collins, HIV i-Base

From April 2011, ARV prescribing in London clinics was changed to reflect the outcomes of therapeutic tendering by the London HIV Specialist Commissioning Group (LSCG) for drugs that have similar activity. This resulted in potential bulk discounts for some drugs if predetermined sales targets were met, while maintaining clinical criteria for prescribing based on efficacy and safety data.

In practice, this involved prescribing Kivexa rather than Truvada, when clinically appropriate for patients starting treatment and use of atazanavir/ritonavir as first-line PI, and switching to atazanavir/ritonavir when clinically appropriate, for patients using other protease inhibitors.

Whilst this important change in public prescribing was undertaken with the assurance of six monthly audits for patient outcomes, the London Commissioners have still to publish their data.

The first public data on the outcomes of one aspect of this policy – use of atazanavir switching – were presented from an audit from the Royal Free Hospital of 201 patients changing PI therapy (total 232 switches) between April 2011 and January 2012. Of these, 21 were excluded as they were switches away from atazanavir/r (62% due to side effects).

The majority (85%) of the remaining cases (153/180) switched to atazanavir/r, half (55%) due to the tender process, 28% for toxicity or intolerance, 7% viral failure/resistance and 10% for other/unknown reasons.

Only 22 people switched to darunavir/r and 5 to lopinavir/r. Reasons for not using atazanavir/r in these patients included: resistance (26%), drug interactions (22%), prior intolerance of atazanavir (11%) and using mono/dual PI therapy (19%).

Rates of short-term discontinuation (within 3 months) were similar in people who switched due to the tender (12/78; 15%) compared switching to atazanavir for other reasons (8/51; 16%), or switching to other ARVs (0/15; 0%), p=0.26. Use of tenofovir had no impact on discontinuation: 16% using tenofovir (14/90) vs 11% without tenofovir (6/54), p=0.46.

Although unrelated to the London guidelines, a separate study from the Chelsea and Westminster Hospital reported on outcomes from 192 patients who switched from lopinavir/r to either atazanavir/r (n=103) or darunavir/r (n=89) from May 2004 to May 2011 and who had at least two years of follow-up.


The London tender is expected to save more than £5 million over the first year with additional savings through to year two.

This snapshot appears to support the safety of the PI-switch component of the London prescription changes.

However this does not replace the Commissioners own audit, results of which are still awaited.


Marshall N et al. Switching to atazanavir due to therapeutic tenders: short term outcomes. 18th BHIVA Conference, 18-20 April 2012, Birmingham. Poster abstract P195. View poster (PDF)

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