A case-control study of percutaneous nephrolithotomy versus extracorporeal shock wave lithotripsy

Objectives To assess the relative efficacy of percutaneous nephrolithotomy (PCN) and extracorporeal shock wave lithotripsy (ESWL) in clearing stones and to examine factors which affected the results from each treatment. Patients and methods The study comprised 390 patients treated with PCN who were compared to 618 patients treated with ESWL, Unconditional logistic regression analysis was used to compare the odds of success and failure in the PCN group with those in the ESWL group, whilst controlling for any potential effects of age, sex, laterality, presence of other stones, previous stone history, pre-operative treatment and centre. Results PCN was more successful in obtaining satisfactory results than ESWL, with an odds ratio of 2.67 (P<0.001, 95% confidence intervals 1.84-3.87). The odds ratio in favour of PCN was increased after controlling for differences by centre (odds ratio 5.18, 95% confidence intervals 2.89-9.16), No other factors significantly influenced the odds ratio, ESWL was less successful in treating stones >2 cm in diameter compared to treating stones <2 cm in diameter (P=0.001), ESWL results were also affected by re-treatment rates, which were influenced by distance of the local hospital from the lithotripter. The results with PCN improved with experience. The results of ESWL were satisfactory and the treatment cheaper, with a lower morbidity and hospital stay than after PCN for stones <2 cm in diameter, making it the treatment of choice. However for stones >2 cm, the results of ESWL were not as good and costs of treatment, morbidity and hospital stay were much closer to those of PCN for similar sized stones. Conclusions PCN is more effective than ESWL in clearing stones. However, ESWL is an effective treatment and is usually the treatment of choice for most stones. Nevertheless, PCN remains an important and extremely effective method of treatment. The choice of treatment for stones will be influenced by the distance of a centre from a static lithotripter, and the potential availability of a mobile lithotripter.