Surveillance of Contact Lens Related Microbial Keratitis in Australia and New Zealand: Multi-Source Case-Capture and Cost-Effectiveness

Abstract

Purpose: To evaluate a multi-source surveillance system used in a 12-month study of contact lens related microbial keratitis in Australia and New Zealand. Methods: All practicing ophthalmologists and optometrists were surveyed on 6 occasions over 12 months via post or the Internet. Participation was defined as reporting at least once during the study period and the response rates represented those who responded on all six occasions. Cases were also detected through hospital audit. All ophthalmologists and a sub-group of optometrists were contacted by phone to elicit a response (active surveillance). The utilization and cost-effectiveness of active surveillance were compared to reports received via the post or the Internet. Case ascertainment and cost-effectiveness were compared for different sources of case capture. Results: The rate of participation for ophthalmologists was 95.8% (711/742) and 88.5% (657/742) responded for all reporting periods. Active surveillance was required for 63% (416/661) of responses in Australia (AU) and 73% (59/81) in New Zealand (NZ) at AUD23.14 per practitioner. Internet reporting was more widely used in New Zealand (NZ: 31% vs. AU:17%, p = 0.006) and was the most cost effective mode of reporting (AUD1.43 per practitioner). Postal reporting (AUD; AU:3.54,NZ:9.84 per practitioner) was under-utilized (3% of responses). Average start-up costs comprised 50% of study costs followed by active follow-up (42%), postal (6%) and Internet reporting (2%). Ophthalmologists (50.4%, 144/286 of cases) were the most cost-effective source of cases, followed by hospital audit (24.5%, 70/286) and optometry (25.1%, 72/286). Duplicate reporting occurred in 13% (37/286) of cases. Conclusions: High response rates were obtained by substantial resource commitment to active follow-up. Internet reporting was widely used and was cost-effective. Hospital audit and supplementary reporting by optometry were used for the first time in a study of contact lens related microbial keratitis, and contributed significantly to case capture.