Feasibility of measuring comorbidity indices based on clinical breast cancer records

Background: Comorbidities have a significant impact on the treatment and outcome of breast cancer. However, data on such comorbidities from low-income countries are limited. Aim: To evaluate the feasibility and accuracy of comorbidity data extracted from medical records for estimating the prevalence of comorbidities among patients registered in the clinical breast cancer registry of the Islamic Republic of Iran. Methods: We collected data from the medical records of 400 patients on 30 comorbidities included in the Charlson Comorbidity Index (CCI) and Elixhauser Comorbidity Index (ECI). The sensitivity and specificity of comorbidity data extracted from medical records were calculated using data from interviews with 97 randomly selected patients. We studied the prevalence of comorbidities using the CCI and ECI. Data were analysed using SPSS version 24. Results: The mean age of patients was 51.69 SD 12.28 years. The sensitivity and specificity of medical records for detecting any comorbidity data contained in CCI versus non-comorbidity were 93.2% and 69.8%, respectively. However, for the comorbidity data included in ECI, both sensitivity (86.9%) and specificity (44.4%) were lower than in CCI. Hypertension (n = 144, 36.0%) and diabetes without chronic complications (n = 77, 19.3%) were the most prevalent comorbidities. A higher proportion of patients had no comorbidity with CCI (72.2%) than with ECI (44.8%). Conclusion: It is feasible to construct a comorbidity index using medical records with high accuracy, especially when we extract comorbidities using the CCI. Further studies are needed to understand the association between comorbidity index and breast cancer survival among Iranian patients.