title: Impact of renal dysfunction on in-hospital mortality of patients with severe chronic obstructive pulmonary disease: a single-center Italian study.
abstract: BACKGROUND
  We conducted a study, based on discharge hospital sheets [International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM)], in order to evaluate the relationship between chronic kidney disease (CKD), acute kidney injury (AKI), multi-morbidity, and in-hospital mortality (IHM).
  
  
  METHODS
  This study included all hospital admissions for chronic obstructive pulmonary disease (COPD) exacerbations between January 1, 2000, and December 31, 2013, recorded in the database of the University Hospital St. Anna of Ferrara. Age, sex, and diagnosis of CKD and AKI were collected, and Charlson comorbidity index (CCI) was calculated by ICD-9-CM codes. IHM was our main outcome.
  
  
  RESULTS
  We analyzed 7073 subjects with COPD exacerbation; they were more frequently male (56.9 vs 43.1 %), and mean age was 76.7 ± 9.8 years. Diagnosis of CKD was present in 771 patients (10.9 %), while AKI was diagnosed in 354 cases (5 %). A total of 554 patients (7.8 %) died during hospitalization, and LOS was 10.3 ± 11.2 days (median 8 days); the CCI corrected for CKD was 2.30 ± 1.65. Univariate analysis showed that IHM group had higher age (81.2 ± 7.9 vs 76.3 ± 9.9 years, p < 0.001), CCI (2.61 ± 2.21 vs 2.28 ± 1.62, p = 0.001), and LOS (11.1 ± 15.1 vs 10.3 ± 10.8 days, p = 0.001) and developed AKI more frequently (16.6 vs 4 %, p < 0.001) than survivors. Multivariate logistic regression analysis showed an independent association of IHM with age (OR 1.063; 95 % CI 1.050-1.075, p < 0.001), male sex (OR 1.229; 95 % CI 1.016-1.486, p = 0.033), logCCI (OR 2.051; 95 % CI 1.419-2.964, p < 0.001), and AKI (OR 3.849; 95 % CI 2.874-5.155, p < 0.001).
  
  
  CONCLUSIONS
  Acute kidney injury (AKI) represents a very important predictive factor of IHM in male older adult with multi-morbidity admitted because of COPD exacerbations.
authors.affiliation: Department of Medical Sciences, Clinica Medica Unit, School of Medicine, University of Ferrara, Via L. Ariosto 35, 44121, Ferrara, Italy. f.fabbian@ospfe.it.
authors.forename: Fabio
authors.identifier: http://orcid.org/0000-0001-5189-3695
authors.initials: F
authors.lastname: Fabbian
authors.affiliation: Department of Medical Sciences, Clinica Medica Unit, School of Medicine, University of Ferrara, Via L. Ariosto 35, 44121, Ferrara, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: De Giorgi
authors.affiliation: Department of Biomedical Sciences and Surgical Specialties, School of Medicine, University of Ferrara, Via L. Ariosto 35, 44121, Ferrara, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Manfredini
authors.affiliation: Department of Biomedical Sciences and Surgical Specialties, School of Medicine, University of Ferrara, Via L. Ariosto 35, 44121, Ferrara, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Lamberti
authors.affiliation: Department of Specialized Medicine, Nephrology Unit, University Hospital of Ferrara, Via A. Moro 8, 44124, Ferrara, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Forcellini
authors.affiliation: Department of Specialized Medicine, Nephrology Unit, University Hospital of Ferrara, Via A. Moro 8, 44124, Ferrara, Italy.
authors.forename: Alda
authors.initials: A
authors.lastname: Storari
authors.affiliation: Department of Internal Medicine, University Hospital of Ferrara, Via A. Moro 8, 44124, Ferrara, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Gallerani
authors.affiliation: Department of Medical Sciences, Cardiorespiratory Unit, School of Medicine, University of Ferrara, Via L. Ariosto 35, 44121, Ferrara, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Caramori
authors.affiliation: Department of Medical Sciences, Clinica Medica Unit, School of Medicine, University of Ferrara, Via L. Ariosto 35, 44121, Ferrara, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Manfredini
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis* / Q000453:epidemiology*; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D016208:Databases, Factual; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality; D006785:Hospitals, University; D006801:Humans; D015994:Incidence; D007558:Italy; D007677:Kidney Function Tests; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D015996:Survival Rate; D017741:Survivors / Q000706:statistics & numerical data
keywords: Acute renal failure; Charlson comorbidity index; Chronic obstructive pulmonary disease; Chronic renal failure; ICD-9-CM; In-hospital mortality