Surgeon predictions on growth of minimal invasive therapy: the difficulty of estimating technologic diffusion

Objective: To compare five-year predictions made in 1991 by academic surgeo n leaders in UK. US and Canada, with actual experiences in 1997. of increas ed rates of minimal invasive therapy (MIT) for surgical operations. Method: We compared 1992 predictions of percent of operations done by minimal inva sive therapy and length of stay in the US with actual 1997 percents found b y literature searches. Results: We found sufficient data on 12 operations d one by MIT in 1997 of the original 34 operations predicted in 1992 by surge on experts to be to be amenable to this technique. These 12 operations were among the top 20 most commonly performed procedures in 1992 and 1997. Of t hese 12 operations, ten had 40-60% lower 1997 percentages than predicted, o ne had about 10% lower rate, and two had 18% and 100% higher rates of MIT t han predicted. Overall mean length of stay (LOS) for all 34 study operation s fell fi om 6.8 days in 1992 to 5.2 days in 1997. Mean LOS in 1997 was 2.5 days by MIT and 6.7 days by open technique (OT). Conclusion: Most of the p redictions made in 1997 by surgical leaders in Canada, US and UK were incor rect when examined 5 years later. The late of MIT diffusion and its effect on length of stay were overestimated for most operations, while for two pro cedures the predictions underestimated extent of diffusion. Also. much of t he declines of LOS for surgical carl paralleled declines in length of stay for all cart, supplemented by the individual contributions of MIT specifica lly. Relying on expert opinion alone to predict the acceptability, rapidity , scope and extent of technological change is fraught with uncertainty. Une xpected consequences occur when one or a few parts of complex systems are c hanged. This is a particular problem when predictions are a main basis for informed decision making in the absence of any supporting data from appropr iately designed empirical or controlled study. (C) 2000 Elsevier Science Ir eland Ltd. All rights reserved.