Sir,

Talks et al1 in their article estimate an incidence of 1300 eligible patients for this treatment in the UK (population of 60 million) using the 2001 NICE guidelines which allowed treatment of second eyes affected by classic choroidal neovascularisation (CNV).2 In 2003, NICE published its recommendations allowing treatment with PDT for all eyes with classic CNV without an occult component (1.1) and recommended predominantly classic with occult CNVs should be treated only as part of on-going or new clinical studies (1.2).2 Their estimate was that 126 per million population (around 7500 patients in the UK) will need PDT annually. We have attempted to determine the impact of NICE guidelines on the PDT service in a DGH serving as primary care centre. In addition, we have also determined the proportion of cases with all primary forms of neovascular AMD eligible for treatment with PDT according to TAP guidelines.

Methods

A total of 205 patients with clinical features of neovascular AMD and vision ⩾6/60 underwent digital fundus fluorescein angiography (FFA) during 2001–2003, during which time we were offering a named-patient NHS PDT service. The first FFA performed for each patient was reviewed unless the second eye presented with CNV, in which case it was included as a new patient. Two reviewers reviewed the stereoscopic FFAs and colour fundus photographs. Determination of lesion type was based on agreement by two graders, with a consensus opinion if there was disagreement. Fluorescein analysis of the components of CNV was defined by the TAP study protocol.3, 4

Results

Fluorescein angiographic characteristics were classified as shown in Table 1. The proportion of patients with classic with no occult CNVs (NICE guidelines 1.1) was 12% (95% CI 11–15). The proportion of patients eligible for treatment according to NICE guidelines 1.1 and 1.2 (TAP guidelines) was 27% (95% CI 24–31).

Table 1 Fluorescein subtypes of CNV
Full size table

Discussion

Based on these figures, we estimate that approximately 11 new PDT treatment courses per year would be required in our catchment population of around 350 000 using NICE guidelines (1.1) or 25 patients under the TAP protocol (NICE 1.1 and 1.2). By extrapolation, the incidence of treatable patients in the whole of UK would be around 1900 if only NICE 1.1 is considered, increasing to 4300 patients if both NICE 1.1 and 1.2 eligible patients are treated (the proposed VPDT cohort study).

While these figures may be an underestimate due to patients presenting late or presenting at other units, we believe that both the proportion of treatable patients and the number of patients from our DGH figures are broadly similar to those presented by Talks et al from a regional centre. Both studies suggest that the number of patients needing PDT will be fewer than that estimated by NICE. These figures may be useful when costing and implementing new PDT services, as recommended by NICE guidelines.