Accuracy and Sensitivity of Parkinsonian Disorder Diagnoses in Two Swedish National Health Registers

Abstract

Background: Swedish population-based national health registers are widely used data sources in epidemiological research. Register-based diagnoses of Parkinson’s disease have not been validated against clinical information. Methods: Parkinson’s disease (PD) and other parkinsonian disorder diagnoses were ascertained in two registers, i.e. the National Patient Register (NPR) and the Cause of Death Register (CDR). Diagnoses were validated in terms of accuracy (positive predictive value) and sensitivity against data from a population-based study of PD in 1998–2004 that screened more than 35,000 persons and identified 194 cases of parkinsonian disorders including 132 PD cases (the gold standard for the purposes of this study). Results: Accuracy for any parkinsonian disorder diagnoses was 88.0% in the NPR and 94.4% in the CDR. Accuracy of PD diagnoses was 70.8% in the NPR and 66.7% in the CDR. Misclassification between differential parkinsonian diagnoses was common. The accuracy of PD diagnoses in the NPR improved to 83.0% by restricting the definition to primary diagnoses only. The sensitivity of PD diagnoses in the NPR and CDR combined was 83.1%, with a mean time to detection of 6.9 years. Conclusions: Population-based national health registers are valid data sources in epidemiological studies of PD or parkinsonian disorder etiology but are less suitable in studies of incidence or prevalence.

Socioeconomic status in relation to Parkinson's disease risk and mortality

“…Second, we obtained PD diagnoses from the National Patient Register in which inpatient PD diagnoses have been validated against clinical diagnoses showing good accuracy; however, misclassification between PD and other parkinsonian disorders occurs. [23] We have no reason to believe that the magnitude of this misclassification differs by SES, therefore resulting in a bias toward the null. Another potential limitation in our study is surveillance bias; [36] participants in higher socioeconomic groups may be more health-conscious, more likely to seek care, resulting in earlier detection of PD.…”

“…Our previous validation of hospital discharge diagnosis of PD against clinical diagnosis showed a positive predictive value of 70.8% and a sensitivity of 72.7%. [23] …”

Alcohol use disorders and risk of Parkinson’s disease: findings from a Swedish national cohort study 1972–2008

“…The accuracy of the PD diagnoses in the Swedish National Inpatient Register has been reported to be 70.8% [9]. The cases were identified by the main and up to seven contributory diagnoses.…”

Occupational stress and risk for Parkinson's disease: A nationwide cohort study

“…On the other hand, if occupational stress or other aspects related to occupation are associated with propensity to seek medical care, this could have differentially biased our results. To increase the accuracy of PD diagnoses, we only included hospital admissions and outpatient visits with PD as the main diagnosis, as suggested by a previous validation study …”

“…Date of ascertainment was defined as the first date of any PD diagnosis in the NPR or date of death in the CDR for those cases only identified at death. A previous validation study concluded that the NPR and CDR are valid data sources in epidemiological studies of PD with generally good accuracy and sensitivity …”