Validation of Secondary Data Sources to Identify Parkinson Disease Against Clinical Diagnostic Criteria

Abstract

Parkinson disease (PD) is the second most common neurodegenerative disorder. Its diagnosis relies solely on a clinical examination and is not straightforward because no diagnostic test exists. Large, population-based, prospective cohort studies designed to examine other outcomes that are more common than PD might provide cost-efficient alternatives for studying the disease. However, most cohort studies have not implemented rigorous systematic screening for PD. A majority of epidemiologic studies that utilize population-based prospective designs rely on secondary data sources to identify PD cases. Direct validation of these secondary sources against clinical diagnostic criteria is lacking. The Framingham Heart Study has prospectively screened and evaluated participants for PD based on clinical diagnostic criteria. We assessed the predictive value of secondary sources for PD identification relative to clinical diagnostic criteria in the Framingham Heart Study (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012). We found positive predictive values of 1.0 (95% confidence interval: 0.868, 1.0), 1.0 (95% confidence interval: 0.839, 1.0), and 0.50 (95% confidence interval: 0.307, 0.694) for PD identified from self-report, use of antiparkinsonian medications, and Medicare claims, respectively. The negative predictive values were all higher than 0.99. Our results highlight the limitations of using only Medicare claims data and suggest that population-based cohorts may be utilized for the study of PD determined via self-report or medication inventories while preserving a high degree of confidence in the validity of PD case identification. Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease. PD afflicts more than 4 million people worldwide and is projected to affect 9 million people by 2030 (1). The etiology for most sporadic cases remains unknown, as genetic variants account for only approximately 10% of cases (2). PD has a low incidence (8-18 per 100,000 person-years), and it is impractical to conduct a prospective, longitudinal epidemiologic study on a condition that relies on a clinical examination for a diagnosis because there is no biomarker or simple laboratory test that can confirm a PD diagnosis except autopsy. Registries for PD that cover large populations do not exist. Case-control studies are often limited by retrospective recall or ascertainment of exposures.Large, population-based, prospective cohort studies designed to examine more common diseases might provide cost-effective ways to study PD within a longitudinal framework. Such studies have accumulated sufficient numbers of patients with incident PD to allow examinations of the associations with multiple potential risk factors and associations that develop over long periods of time. Indeed, the use of existing cohorts to study PD has resulted in numerous significant findings (2). However, most cohort studies have not implemented rigorous systematic screening for PD and have necessarily re...

Prevalence and Correlates of Anti‐Parkinson Drug Use in a Nationally Representative Sample

“…Because our goal was to describe prescription drug utilization and patterns, we chose a PD case definition that optimized sensitivity first and then specificity. Prior studies have compared the accuracy of Medicare claims in the identification of PD; however, they employed slightly different methodologies . Noyes and colleagues compared PD diagnosis by self‐report (“Have you ever been told you have Parkinson's disease?”) against physician‐only claims for ICD code 332.0 and found that the highest positive predictive value was 74%.…”

“…This method optimizes sensitivity (range, 64-89%) over specificity (range, 28-99%) based on prior studies that have evaluated the diagnostic accuracy of administrative claims compared with the gold standard of either self-reported diagnoses or review of clinical information. [13][14][15][16] However, to further improve the specificity of our case definition, and to decrease the risk of misclassification of secondary parkinsonian syndromes in our cohort, we also excluded individuals with a history of schizophrenia (ICD 295) or secondary/atypical parkinsonism (ICD codes 332.1 and 333.X). Similar case ascertainment methods have been used in previous health care utilization studies of Medicare populations.…”

Explanation and Elaboration of the Standards of Reporting of Neurological Disorders Checklist: A Guideline for the Reporting of Incidence and Prevalence Studies in Neuroepidemiology

“…Algorithms validated in adults have been demonstrated to be inaccurate for the identification of children with the same disease [31,32], and some algorithms are more sensitive for older adults compared with younger adults [33]. A recent study by Jain et al [34] highlighted the limitations of using Medicare claims data as the main secondary source of identifying Parkinson's disease (PD) compared to PD identified via self-report or use of anti-parkinsonian medications. In a systematic review, St. Germaine-Smith et al [35] concluded that in order to ensure that population-based studies of neurological conditions that used administrative datasets were interpreted correctly, the accuracy of the case-definition should be carefully scrutinised.…”

The end of life with PD can be well-lived

“…Safarpour et al 2 used routinely collected administrative data provided by Medicaid in their analysis. 9 Safarpour et al 2 identified their PD cases using the ICD-9 332 diagnostic code from physician/ carrier claims, excluding beneficiaries with a concomitant diagnosis of Parkinson-plus syndrome. A number of validated methods for accurately identifying PD in Medicaid and related databases exist, 8-10 as contrasted with selfreport (e.g., "Have you ever been told you had Parkinson disease?").…”

“…A number of validated methods for accurately identifying PD in Medicaid and related databases exist, 8-10 as contrasted with selfreport (e.g., "Have you ever been told you had Parkinson disease?"). 8,9 Whether or not missed cases of PD were systematically different in their demographic characteristics or outcomes is unknown, and we do not know how relevant the reported 2002-2005 data are to practice in 2015. One longitudinal populationbased study reported that only 40% of self-reported PD cases had typical neuropathology findings in a small postmortem sample, 10 although another study suggested greater specificity of self-report in a relatively young PD cohort when compared against clinical assessment.…”