title: Obtaining the mean relative weights of the cost of care in Catalonia (Spain): retrospective application of the adjusted clinical groups case-mix system in primary health care.
abstract: OBJECTIVE
  The study aims to obtain the mean relative weights (MRWs) of the cost of care through the retrospective application of the adjusted clinical groups (ACGs) in several primary health care (PHC) centres in Catalonia (Spain) in routine clinical practice.
  
  
  METHODS
  This is a retrospective study based on computerized medical records. All patients attended by 13 PHC teams in 2008 were included. The principle measurements were: demographic variables (age and sex), dependent variables (number of diagnoses and total costs), and case-mix or co-morbidity variables (International Classification of Primary Care). The costs model for each patient was established by differentiating the fix costs from the variable costs. In the bivariate analysis, the Student's t, analysis of variance, chi-squared, Pearson's linear correlation and Mann-Whitney-Wilcoxon tests were used. In order to compare the MRW of the present study with those of the United States (US), the concordance [intraclass correlation coefficient (ICC) and concordance correlation coefficient (CCC)] and the correlation (coefficient of determination: R²) were measured.
  
  
  RESULTS
  The total number of patients studied was 227,235, and the frequentation was 5.9 visits/habitant/year) and with a mean diagnoses number of 4.5 (3.2). The distribution of costs was €148.7 million, of which 29.1% were fixed costs. The mean total cost per patient/year was €654.2 (851.7), which was considered to be the reference MRW. Relationship between study-MRW and US-MRW: ICC was 0.40 [confidential interval (CI) 95%: 0.21-0.60] and the CCC was 0.42 (CI 95%: 0.35-0.49). The correlation between the US MRW and the MRW of the present study can be seen; the adjusted R² value is 0.691. The explanatory power of the ACG classification was 36.9% for the total costs. The R² of the total cost without considering outliers was 56.9%.
  
  
  CONCLUSIONS
  The methodology has been shown appropriate for promoting the calculation of the MRW for each category of the classification. The results provide a possible practical application in PHC clinical management.
authors.affiliation: Directorate of Planning, Badalona Serveis Assistencials SA, Badalona, Spain. asicras@bsa.cat
authors.forename: Antoni
authors.initials: A
authors.lastname: Sicras-Mainar
authors.forename: Soledad
authors.initials: S
authors.lastname: Velasco-Velasco
authors.forename: Ruth
authors.initials: R
authors.lastname: Navarro-Artieda
authors.forename: Alba
authors.initials: A
authors.lastname: Aguado Jodar
authors.forename: Oleguer
authors.initials: O
authors.lastname: Plana-Ripoll
authors.forename: Eduardo
authors.initials: E
authors.lastname: Hermosilla-Pérez
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Bolibar-Ribas
authors.forename: Alejandra
authors.initials: A
authors.lastname: Prados-Torres
authors.forename: Concepción
authors.initials: C
authors.lastname: Violan-Fors
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003365:Costs and Cost Analysis / Q000379:methods; D003953:Diagnosis-Related Groups / Q000191:economics*; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D038801:International Classification of Diseases; D008297:Male; D008485:Medical Audit; D008875:Middle Aged; D011320:Primary Health Care / Q000191:economics*; D012189:Retrospective Studies; D020379:Risk Adjustment / Q000191:economics; D013030:Spain; D055815:Young Adult