Missing.... presumed at random: cost-analysis of incomplete data

When collecting patient-level resource use data for statistical analysis, for some patients and in some categories of resource use, the required count will not be observed. Although this problem must arise in most reported economic evaluations containing patient-level data, it is rare for authors to detail how the problem was overcome. Statistical packages may default to handling missing data through a so-called complete case analysis, while some recent cost-analyses have appeared to favour an available case approach. Both of these methods are problematic: complete case analysis is inefficient and is likely to be biased; available case analysis, by employing different numbers of observations for each resource use item, generates severe problems for standard statistical inference. Instead we explore imputation methods for generating replacement values for missing data that will permit complete case analysis using the whole data set and we illustrate these methods using two data sets that had incomplete resource use information

A clinical and economic evaluation of contact laser surgery in the prostate.

Contact laser prostatectomy is an exciting new surgical technique, that in theory, can produce clinical results comparable to those obtainable with standard transurethral resection. This thesis has rigorously evaluated this technology in the context of a pragmatic, double blind randomised controlled clinical trial looking at traditional physiological outcome parameters, more subjective measures, as well as the increasingly important economic side of new technology. One hundred and forty eight patients with lower urinary tract symptoms attributable to benign prostatic enlargement were randomised to either transurethral resection (TURP) or contact laser prostatectomy; one year data were available on 126. Symptom score was the defined primary outcome measure, which statistically favoured the TURP arm throughout. However, when considering the clinically more important absolute change in symptoms, there was no difference between the two treatment arms of the study. Rigorous economic analysis has shown TURP to be less expensive, unless length of hospital stay following laser surgery is reduced to one night. Little change in quality of life as measured by the Short Form 36 generic health questionnaire between baseline and one year. In conclusion, contact laser vaporisation of the prostate can produce similar results to TURP in terms of symptomatic improvement, with less primary and reactionary haemorrhage but in this study, at a cost of a higher rate of failing trial without catheter and an increased re-operation rate. Interestingly, prostatectomy by whichever method has led to little improvement in general health status one year following surgery