Inter-rater reliability of the ICPC-2 in a German general practice setting

Three- and four-digit International Classification of Diseases (ICD-10) is not a reliable classification system in primary care. The reliability of the International Classification of Primary Care (ICPC-2) as an alternative coding system has not yet been investigated in a German general practice setting. Cross-sectional data were collected during a one year period in a general practice setting. A total of 8,877 patients were randomly selected. The first of the reasons for encounter was taken into account on new and chronic managed problems. The ICPC-2 coding of each case was performed by two raters to investigate the inter-rater agreement. The degree of agreement between the raters was assessed by using Cohen's kappa (κ ≥ 0.61 meaning high or satisfactory and κ ≤ 0.6 (incl. ≤ 0.000) meaning low or unsatisfactory). The reliability was good to excellent at the chapter level, at the component level the reliability was moderate though good in the components 1-symptoms and 7-diseases. At single code level the agreement was only fair to moderate in both chapters and components. One third to half of the used codes showed good inter-rater agreement. The ICPC-2 is an adequate and feasible instrument for routine use in general practice. The fair to moderate reliability on the single code level should be considered when designing studies and interpreting data that are based on the ICPC-2.