Development and assessment of a priority score for cataract surgery.

ABSTRACT

BACKGROUND: Point-count measures of clinical priority are increasingly put forward for managing waiting lists. However, their development does not consider explicitly the appropriateness of the indications. Furthermore, an estimate of their effect in clinical practice is needed, assessing the amount of gains and losses in terms of time waited for patients with different priority scores. METHODS: We developed appropriateness criteria for cataract surgery using the RAND method and applied them to a sample of 567 patients consecutively placed on a waiting list for cataract surgery. In addition, clinicians were asked to express the priority attributed to each patient using a 10-cm visual analogue scale, where 0 = minimal priority and 10 = maximum priority. We developed a priority score, using regression analysis to identify the set of clinical characteristics that best predicted clinicians' priority rating and to estimate their individual weight. We used a computer simulation model to compare mean waiting times with management of the waiting list using the priority score and using the "first-come, first-served" approach. RESULTS: Overall, 332 patients (60.8%) were referred for cataract surgery for indications deemed appropriate, and their mean priority rating was 5.9 (95% confidence interval [CI] 5.7-6.1). The corresponding figures for the 201 (36.8%) uncertain indications and the 13 (2.4%) inappropriate indications were 4.5 (95% CI 4.1-4.7) and 2.6 (95% CI 1.3-3.9) respectively. The clinical characteristics included in the priority score (visual acuity in the operated eye and in the contralateral eye, visual function and ability to live or work independently) accounted for 35% of the variance in clinicians' ratings of priority. In the computer simulation model, patients with the highest priority experienced a variable reduction in mean waiting time (9% to 27%) depending to how time spent waiting was integrated into the clinical score. INTERPRETATION: We conclude that the use of priority ratings in the management of a waiting list for cataract surgery leads to results that maintain the desirable coherence between priority and appropriateness of indication. The results also suggest that the implementation in clinical practice of priority scores may be worth the effort, given the potential reduction in waiting time for patients at high priority.