Prone versus modified supine percutaneous nephrolithotomy: which is more cost effective in an Australian tertiary teaching hospital?

Introduction: Percutaneous nephrolithotomy is currently one of the main treatment options for large renal stones, but the effect of positioning on comparative costing has been scarcely documented. We aimed to compare the cost effectiveness of modified supine with traditional prone percutaneous nephrolithotomy procedures in the context of Victoria, Australia. Materials and methods: A prospective group of 236 renal units (224 patients) was included in the two-site study, with 76 performed in the prone position and 160 performed in the modified supine position. Costing was calculated using a 'bottom-up', all-inclusive framework that generates per-hour costs for theatre, recovery unit and ward costs from base costs and maintenance costs. Percutaneous nephrolithotomy-specific equipment was added to calculate comparative costs of modified supine versus prone procedures. Chi squared and T tests were used for statistical analysis. Results: There was a significant difference in the overall costing between the modified supine and prone groups. The modified supine group had a lower total cost (AUD$6424.29) compared to the prone group (AUD$7494.79) (P=0.007), lower operative costs (AUD$4250.93 vs. AUD$5084.29, P=0.002) and lower ward costs (AUD$533.55 vs. AUD$1130.20, P<0.001). There was no significant difference in recovery times in the modified supine and prone groups, although the modified supine group appeared to have shorter recovery times (AUD$690.69 vs. AUD$586.05, P=0.209). Conclusions: Modified supine percutaneous nephrolithotomy has significantly lower total costs, operative costs and ward costs compared to prone percutaneous nephrolithotomy. Larger randomised trials are needed to assess these findings further.