Introduction of photodynamic therapy for the treatment of neovascular age-related macular degeneration: tracking a moving target.

OBJECTIVES: To identify changes in referral and treatment patterns of neovascular age-related macular degeneration with photodynamic therapy (PDT) within ophthalmology units in NHS hospitals and assess how beliefs about what would constitute a worthwhile level of clinical benefit had altered over a 12-month period.

METHODS: Two questionnaire surveys (October 2000 and October 2001) to all clinical directors or lead consultants in UK NHS eye units. These sought data on which (if any) patients were referred or treated with PDT and the threshold of clinical benefit, in terms of numbers needed to treat, at which they would support the use of PDT.

RESULTS: Response rates were 82% in the first survey and 79% in the second. The availability of PDT had significantly increased (P=0.0001). The proportion of units routinely providing PDT for patients with more than 50% classic subfoveal choroidal neovascularization (CNV) increased from 8 to 23%. Between the 2 surveys, there was a significant reduction in the threshold of effectiveness at which respondents would support the use of PDT (P=0.012). The proportion of respondents requiring further evidence before supporting the use of PDT decreased from 33 to 17% (P=0.009). There was a significant association between the threshold of support and the level of service provision for both surveys (P=0.01).

CONCLUSIONS: Although substantial variations exist, availability of PDT has increased over the 12-month period. The differing thresholds at which introduction of PDT would be considered justifiable varied widely. PDT is being introduced into the NHS in a fragmented manner. In common with other new health technologies, factors other than the strength of evidence appear to be influencing beliefs about the effectiveness of PDT and its subsequent provision. While it is unlikely that such an action alone will lead to evidence-based practice, the variations in beliefs identified by this survey suggest that sufficient clinical uncertainty exists to support the need for further clinical trials.