Efficacy and costs of ambulatory cataract surgery

Methodological quality of the review: Low confidence

Author: Castells X, Alonso J, Castilla M, Comas M.

Region: United States of America (USA), United Kingdom (UK), Spain and Norway

Sector: cataract surgery

Sub-sector: Cost-effectiveness

Type of cataract: Age-related cataract

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis methods: Not applicable


Ambulatory cataract surgery is a result of technical and scientific advances and cost containment policies. There are important differences between countries in terms of their rates of ambulatory cataract surgery. This review attempts to provide a formal evaluation of the current evidence supporting the cost-effectiveness of ambulatory cataract surgery.

Authors hypothesized that: ambulatory cataract surgery has lower cost than in-patient cataract surgery and is no different in relation to the benefits (visual acuity) or the adverse effects (surgical complications).

Research objectives

  • To compare postoperative visual acuity in ambulatory and in-patient cataract surgeries;
  • To compare the cost of ambulatory and in-patient cataract surgery;
  • To compare the rate of postoperative complications in ambulatory and in-patient cataract surgery.

Main findings

Authors included five clinical trials and 10 observational studies. The studies are from the USA, UK, Norway and Spain. Nine studies analysed the clinical results of each surgical modality, three studies analysed costs and three analysed both clinical results and costs. The results of the quantitative synthesis showed:

  • Outpatients presented a higher rate of postoperative complications: OR= 1.4; IC 95%: 1.1 -1.8;
  • Outpatients had a higher rate of postoperative raised intraocular pressure: OR=2.3; IC 95%: 1.3-3.9;
  • Ambulatory surgery costs were 15-30% lower than in-patient surgery costs.

The authors made the point that given the high frequency of cataract surgical procedures, the impact of the results (both in terms of complications and savings) at population level is very considerable.

Authors concluded that ‘Ambulatory cataract surgery patients present a benefit in visual acuity similar to in-patients. However, the higher risk of surgical complications among outpatients suggests the appropriateness of improving their immediate postoperative care. Even though some variability exists in the method to calculate costs, the results suggest that ambulatory surgery is the most efficient alternative.’

The studies included are powered to demonstrate differences in visual acuity and not in complications. The authors noted that conducting observational studies using large administrative patient databases could complement the evidence from clinical trials.


Authors included studies in: a) evaluating cataract surgery patients, b) comparing ambulatory surgery patients with cataract surgery in-patients, c) evaluating at least one of the following variables: postoperative visual acuity, postoperative complications rate, direct surgical costs, d) randomized controlled trial designs and case series. Outcome measures included postoperative visual acuity, postoperative complication rate, and surgical costs.

Authors conducted a search of Medline (1985-1998), HealthStar (1975-1998), Evidence-based American Academy of Ophthalmologists, Ophthalmology, Archives of Ophthalmology, Journal of Cataract and Refractive Surgery (1992-1998), and of reference lists of articles revised. Quality of trials was assessed using the criteria from the Evidence-Based Medicine Working Group and CONSORT Statement. The statistical power for each variable was calculated for each trial.

Quantitative synthesis was performed on the percentage of complications in the studies. Homogeneity tests (DerSimonian and Laird) were used to adjust aggregated results and a fixed-effects model was used. The Absolute Risk Difference and the Number Needed to Treat were calculated. Odds ratios for each study and a pooled odds ratio were calculated for the complications rate.

Applicability/external validity

The authors did not discuss the applicability/external validity of the results.

Geographic focus

Although authors did not find studies from low- and middle- income settings, results are applicable. The lower costs of ambulatory surgery are appealing in low-income settings where resources are scarce. However, issues of access to surgery in areas where patients might travel far for treatment should be considered in many low-income settings. These could make in-patient surgery the only solution where services are limited, despite the higher cost.

Quality assessment

Low confidence was attributed in the conclusions about the effects of this review as major limitations were identified. The literature search, while covering a range of journals, one database and reference lists, was not sufficiently comprehensive that we can be confident that relevant literature was not omitted. Additionally, it was not clear from the review if language bias was avoided, if independent screening of full text and data extraction as conducted by two reviewers.  Authors assessed the quality of the clinical trials included in the review, although they did not discuss the quality of the 10 observational studies included. Nevertheless, authors appropriately described the extent of heterogeneity and examine the extent to which specific factors might explain differences in the results of the included studies.

Publication Details

Castells X, Alonso J, Castilla M, Comas M. Eficacia y costes de la cirugía ambulatoria de cataratas: revisión sistemática de la bibliografía. Medicina Clínica (Barcelona). 2000;Volumen 114:40-7.