Open Access Research article

Validity of registration of ICD codes and prescriptions in a research database in Swedish primary care: a cross-sectional study in Skaraborg primary care database

Per Hjerpe12*, Juan Merlo23, Henrik Ohlsson23, Kristina Bengtsson Boström1 and Ulf Lindblad4

Author Affiliations

1 R&D Centre, Skaraborg Primary Care, Skövde, Sweden

2 Social Epidemiology, Department of Clinical Sciences, Faculty of Medicine, Lund University, Sweden

3 Unit for Primary Health Research, Region Skåne, Sweden

4 Department of Public Health and Community Medicine/Primary Health Care, The Sahlgrenska Academy at the University of Gothenburg, Sweden

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BMC Medical Informatics and Decision Making 2010, 10:23  doi:10.1186/1472-6947-10-23

Published: 23 April 2010

Abstract

Background

In recent years, several primary care databases recording information from computerized medical records have been established and used for quality assessment of medical care and research. However, to be useful for research purposes, the data generated routinely from every day practice require registration of high quality. In this study we aimed to investigate (i) the frequency and validity of ICD code and drug prescription registration in the new Skaraborg primary care database (SPCD) and (ii) to investigate the sources of variation in this registration.

Methods

SPCD contains anonymous electronic medical records (ProfDoc III) automatically retrieved from all 24 public health care centres (HCC) in Skaraborg, Sweden. The frequencies of ICD code registration for the selected diagnoses diabetes mellitus, hypertension and chronic cardiovascular disease and the relevant drug prescriptions in the time period between May 2002 and October 2003 were analysed. The validity of data registration in the SPCD was assessed in a random sample of 50 medical records from each HCC (n = 1200 records) using the medical record text as gold standard. The variance of ICD code registration was studied with multi-level logistic regression analysis and expressed as median odds ratio (MOR).

Results

For diabetes mellitus and hypertension ICD codes were registered in 80-90% of cases, while for congestive heart failure and ischemic heart disease ICD codes were registered more seldom (60-70%). Drug prescription registration was overall high (88%). A correlation between the frequency of ICD coded visits and the sensitivity of the ICD code registration was found for hypertension and congestive heart failure but not for diabetes or ischemic heart disease.

The frequency of ICD code registration varied from 42 to 90% between HCCs, and the greatest variation was found at the physician level (MORPHYSICIAN = 4.2 and MORHCC = 2.3).

Conclusions

Since the frequency of ICD code registration varies between different diagnoses, each diagnosis must be separately validated. Improved frequency and quality of ICD code registration might be achieved by interventions directed towards the physicians where the greatest amount of variation was found.