Construction and validation of a morbidity index based on the International Classification of Primary Care

Abstract

Objectives In epidemiological studies it is often necessary to describe morbidity. The aim of the present study is to construct and validate a morbidity index based on the International Classification of Primary Care (ICPC-2). Design and Setting This is a cohort study based on linked data from national registries. An ICPC morbidity index was constructed based on a list of longstanding health problems in earlier published Scottish data from general practice and adapted to diagnostic ICPC-2 codes recorded in Norwegian general practice 2015 − 2017. Subjects The index was constructed among Norwegian born people only ( N = 4 509 382) and validated in a different population, foreign-born people living in Norway ( N = 959 496). Main outcome measures Predictive ability for death in 2018 in these populations was compared with the Charlson index. Multiple logistic regression was used to identify morbidities with the highest odds ratios (OR) for death and predictive ability for different combinations of morbidities was estimated by the area under receiver operating characteristic curves (AUC). Results An index based on 18 morbidities was found to be optimal, predicting mortality with an AUC of 0.78, slightly better than the Charlson index (AUC 0.77). External validation in a foreign-born population yielded an AUC of 0.76 for the ICPC morbidity index and 0.77 for the Charlson index. Conclusions The ICPC morbidity index performs equal to the Charlson index and can be recommended for use in data materials collected in primary health care. Key points This is the first morbidity index based on the International Classification of Primary Care, 2 nd edition (ICPC-2) It predicted mortality equal to the Charlson index and validated acceptably in a different population The ICPC morbidity index can be used as an adjustment variable in epidemiological research in primary care databases

Continuity and breaches in GP care and their associations with mortality for patients with chronic disease: an observational study using Norwegian registry data

“… b Number of comorbidity groups based on ICPC Morbidity Index. 28 Data are n (%) apart from for the Mean age row. COPD = chronic obstructive pulmonary disease.…”

“…b Number of comorbidity groups based on ICPC Morbidity Index. 28 ICPC = International Classification of Primary Care. UPC = Usual Provider of Care Index (where 1 = all consultations by the RGP).…”

“…24 Highest level of education is categorised as low (elementary school or less), medium (upper secondary school), and high (university and higher education). 25 For comorbidities the ICPC Morbidity Index 28 was used divided into four groups (0, 1, 2, and ≥3 comorbidities).…”

The 40 th Anniversary of the Scandinavian Journal of Primary Health Care

“…That very same Bent Guttorm Bentsen, as well as Niels Bentzen (Denmark), were among this committee’s pioneering members. By 1975, the first International Classification of Health Problems in Primary Care (ICPC) was published, which soon became a fundamental primary healthcare research tool [ 6 ].…”

Patient Characteristics and Healthcare Use for High-cost Patients with Musculoskeletal Disorders in Norway: A Cohort Study

“…Data sources, variables and variable de nitions comorbidity index from GP-diagnoses based on ICPC-2 diagnoses, which have been validated to be used as an adjustment variable in epidemiological research in primary care databases(55). This is a comorbidity index based on primary care data with eighteen selected diagnoses and the individual patient are assigned an index score based on number of diagnoses that can be identi ed.…”