Evaluating regional variability in the use of the most commonly requested laboratory tests in primary care in Spain: data from the multi-center national scale REDCONLAB initiative

Abstract Background: The aim was to study the regional variability in the request of the ten most frequently ordered laboratory tests in primary care in Spain. Methods: Spain is divided into autonomous communities (AACC), first level health care divisions. Every AACC is divided into health departments (HDs). A laboratory attends the needs of every HD inhabitant. Laboratories from different HDs participated in the study. They reported the request of the ten most commonly requested laboratory tests in primary care during the year 2014 according to prior evidence: alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol, creatinine, γ-glutamyl transpeptidase (GGT), glucose, HDL-cholesterol, triglycerides, uric acid and urinalysis. Test-utilization rates were calculated as tests per 1000 inhabitants. Laboratories were grouped in the different AACC and the results for each region were compared using the coefficient of quartile dispersion (CQD), calculated using the first (Q1) and third (Q3) quartiles for each data set, as follows: (Q3−Q1)/(Q3+Q1). Results: One hundred and ten laboratories participated, corresponding to 27,798,262 inhabitants (59.8% Spanish population) from 15 AACC. 82,710,869 tests were requested. AST, GGT and uric acid showed the greatest variation. Conclusions: There were significant regional differences in how the most common laboratory tests were ordered in Spain.