Longitudinal analysis in the medical sciences: anapplication to the investigation of postnephrectomy course

We present the initial results of a retrospective study conducted on 245 patients who underwent unilateral Radical Nephrectomy (RN) as treatment of an urological pathology. The recorded postoperative creatinine levels are analysed for determining the principal patterns of variation in the two years following the intervention. The observational data, which are sparse and right censored, are linearly interpolated and then analysed via a robust form of Principal Component Analysis (PCA). The results seem to indicate that the quantitative description of the main patterns can be reduced to few descriptive measures based on post-operative observations.