title: Concealed renal failure and adverse drug reactions in older patients with type 2 diabetes mellitus.
abstract: BACKGROUND
  In elderly patients serum creatinine may be normal despite decreased glomerular filtration rate (GFR). The aim of this study was to evaluate the prevalence of this "concealed" renal failure, i.e., renal failure with normal serum creatinine levels, in elderly diabetic patients, and to verify whether it is a risk factor for adverse drug reactions (ADR) to hydrosoluble drugs.
  
  
  METHODS
  We used data on 2257 hospitalized patients with type 2 diabetes mellitus enrolled in the Gruppo Italiano di Farmacovigilanza nell'Anziano study. On the basis of serum creatinine and calculated GFR, patients were grouped as follows: normal renal function (normal serum creatinine levels and normal GFR), concealed (normal serum creatinine levels and reduced GFR), or overt (increased creatinine levels and reduced GFR) renal failure. GFR was calculated using the Modification of Diet in Renal Disease (MDRD) equation. The outcome of the study was the incidence of ADR to hydrosoluble drugs during the hospital stay. The relationship between renal function and ADR was evaluated using Cox regression analysis including potential confounders.
  
  
  RESULTS
  Concealed renal failure was observed in 363 (16.1%) of patients studied. Patients with concealed or overt renal failure were older, had more frequently cognitive impairment and polypharmacy, and had lower serum albumin levels than did those with normal renal function. Both concealed (hazard ratio = 1.90; 95% confidence interval, 1.04-3.48; p =.036) and overt (hazard ratio = 2.23; 95% confidence interval, 1.40-3.55; p =.001) renal failure were significantly associated with ADR to hydrosoluble drugs. The use of more than four drugs also qualified as an independent risk factor for ADRs to hydrosoluble drugs during hospital stay.
  
  
  CONCLUSIONS
  Older diabetic patients should be systematically screened to ascertain the presence of concealed renal failure in an attempt to optimize the pharmacological treatment and reduce the risk of ADRs.
authors.affiliation: Divisione di Medicina Geriatrica, Istituto Nazionale di Ricovero e Cura per Anziani, Cosenza, Italy. andrea_corsonello@tin.it
authors.forename: Andrea
authors.initials: A
authors.lastname: Corsonello
authors.forename: Claudio
authors.initials: C
authors.lastname: Pedone
authors.forename: Francesco
authors.initials: F
authors.lastname: Corica
authors.forename: Bruno
authors.initials: B
authors.lastname: Mazzei
authors.forename: Angelo
authors.initials: A
authors.lastname: Di Iorio
authors.forename: Pierugo
authors.initials: P
authors.lastname: Carbonin
authors.forename: Raffaele Antonelli
authors.initials: RA
authors.lastname: Incalzi
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications* / Q000188:drug therapy; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007004:Hypoglycemic Agents / Q000009:adverse effects*; D007676:Kidney Failure, Chronic / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D015415:Biomarkers; D007004:Hypoglycemic Agents; D003404:Creatinine