title: Measured-to-predicted creatinine generation ratio increases with time and decline in residual renal function in continuous ambulatory peritoneal dialysis.
abstract: The expression of measured-to-predicted creatinine generation ratio (M/P) has been proposed as an index of compliance in continuous ambulatory peritoneal dialysis (CAPD) patients. Although M/P may not be sensitive enough for cross-sectional study, serial monitoring has been suggested to identify noncompliance. We attempted to evaluate serial changes of M/P from a nonselected group of CAPD patients. Sixty-three patients, all followed up for 2 years, were reviewed retrospectively. Their M/P ratios at years 0 and 2 were computed and compared. Baseline M/P had a normal distribution with a mean of 0.96 +/- 0.26. There was significant correlation between baseline M/P and residual glomerular filtration rate (GFR; r = -0.81; P < 0.0001). There were weak correlations between M/P and duration of dialysis (r = 0.52; P < 0.0001), body weight (r = -0.52; P < 0.0001), Kt/V (r = 0.31; P < 0.02), weekly creatinine clearance normalized to body surface area (r = 0.53; P < 0.0001), and serum albumin level (r = -0. 28; P < 0.05). After 2 years, M/P increased in 56 of 63 patients (88. 9%). Average M/P increased from 0.96 +/- 0.26 to 1.31 +/- 0.27 (P < 0.0001). Multivariant analysis showed M/P at year 0, which was largely determined by residual GFR, was the only independent factor affecting increase in M/P from year 0 to year 2. The general trend of increasing M/P was still present when only anuric patients were analyzed, although that was not statistically significant (1.21 +/- 0.14 to 1.32 +/- 0.24; P = 0.12). The finding of increasing M/P with time in CAPD patients, particularly those with significant residual renal function, suggests M/P may not be a reliable indicator of noncompliance, even for serial follow-up of the same patient. Better methods for assessment of compliance in CAPD patients are required.
authors.affiliation: Department of Medicine and Therapeutics, Prince of Wales Hospital, Shatin, Hong Kong, China.
authors.forename: C C
authors.initials: CC
authors.lastname: Szeto
authors.forename: K N
authors.initials: KN
authors.lastname: Lai
authors.forename: T Y
authors.initials: TY
authors.lastname: Wong
authors.forename: M C
authors.initials: MC
authors.lastname: Law
authors.forename: P K
authors.initials: PK
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D001002:Anuria / Q000378:metabolism / Q000628:therapy; D003404:Creatinine / Q000378:metabolism*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010349:Patient Compliance; D010531:Peritoneal Dialysis, Continuous Ambulatory; D012189:Retrospective Studies; D012709:Serum Albumin / Q000032:analysis; D013997:Time Factors; D014508:Urea / Q000378:metabolism
chemical_list: D012709:Serum Albumin; D014508:Urea; D003404:Creatinine