Table 3 Study populations and case ascertainment methods
From: Prevalence of Parkinson’s disease across North America
Study | Honolulu-Asia Aging Study | Ontario, Canada | Kaiser Permanente Northern California | Rochester Epidemiology Project | California PD registry project | US Medicare |
|---|---|---|---|---|---|---|
Base population | 8006 Japanese-American men born 1900–1919, living in Honolulu county, Hawaii, USA at baseline in 1965 and participating in the longitudinal Honolulu Heart Program | Residents of Ontario, Canada; all are provided health care paid for by the provincial government | Members of the Kaiser Permanente Northern California, a closed integrated health-care delivery system providing health insurance and health care to 25–30% of the population of Northern Californiaa | Residents of Olmsted county, Minnesota, USA | Residents of Kern, Tulare, Fresno, Santa Clara counties, California, USA | Residents of USA aged ≥65 years who use Medicare as their health-care insurer and whose insurance claims are released to Medicareb |
Ascertainment method(s)/data source | Pre-1991: Hospitalization records, outpatient medical records, Post-1991: Screening in-person exam by trained research technician, positive cases examined by neurologist | Ontario Health-care administrative databases recording all inpatient and outpatient physician encounters | Medical record ascertainment that combined inpatient and outpatient diagnostic, pharmacy, treatment, and physician type15 | Electronic screening for 53 H-ICDA codes for PD, parkinsonism, tremor, PSP, MSA, other extrapyramidal syndromes, non-specific neuro-degenerative diseases, followed by manual medical record review by neurologist28 | Neurologists and large group practices asked to report all patients with ICD-9 code of PD (332) or other parkinsonism (332.1, 333.0, or 331.82). Trained abstractors manually extracted relevant elements of medical record | Medicare administrative claims database |
Diagnostic criteria | Consensus diagnosis by movement disorders experts using hospitalization, outpatient neurologist records, and additionally after 1991 study screening examination and study neurologist’s standardized examination and Ward and Gibb criteria29 | One hospitalization record or two outpatient visits with an assigned ICD diagnosis of PD (332 or G20) in the administrative record30 | Algorithm that combines number of PD diagnoses, expertise of the physician making the diagnoses, and treatment | The presence of two of four cardinal signs: resting tremor, bradykinesia, rigidity, and impaired postural reflexes, without a known secondary cause, documented levodopa unresponsiveness or other atypical features28 | ICD-9 code for PD (332). If more than one parkinsonism code was reported, manual medical record review by a movement disorder neurologist (CMT) to assign the most likely diagnosis | One ICD code for PD (332.0) and no atypical or secondary parkinsonism codes |
Case definition validation method(s), if any | None | Medical record review. Sensitivity 72%, specificity 99%30 | None | Clinicopathologic concordance 87% in 60 individuals31 | A minimum of 10% validation using standardized chart abstraction protocol | None |
