SMALL AREA ANALYSIS OF LUMBAR SPINE SURGERY IN SOUTH AUSTRALIA

The hospital separation records for 1987 in the health planning region s of South Australia were reviewed using a selection algorithm to iden tify all hospitalizations involving a lumbar spine surgery (LSS) for l ow back or leg pain. Among 16 health planning regions (two additional regions were excluded from the analysis because of the low number of o bservations) the LSS rate varied almost four-fold, from 25 to 92/100 0 00; with a mean of 55/100000. The effect of 24 socioeconomic and healt h care supply characteristic variables upon observed differences in ra tes were tested. The unemployment rate was the only significant variab le in the analysis, explaining 11 % of the variation in the surgery ra tes for the 16 regions. This finding is in agreement with studies from other countries that suggest that characteristics of small areas do n ot substantially predict the rates of elective surgical procedures. Th e decision-making processes of surgeons and their patients remain poor ly defined; the contributions to the rate of lumbar spine surgery by t he health care delivery system, physician behaviours or patient expect ations are not yet identified.