Ongoing challenges to finding people with Parkinson’s disease for epidemiological studies: A comparison of population-level case ascertainment methods

Linking Individual Patient Data to Estimate Incidence and Prevalence of Parkinson's Disease by Comparing Reports of Neurological Services and Pharmacy Prescription Refills at a Nationwide Level

Objectives: We set forth to estimate the number of those with Parkinson's disease (PD) in Hungary, a country with a single-payer health insurance system covering 10 million inhabitants.

Methods: We analyzed all hospital and outpatient reports from neurological services and pharmacy reports of prescription refills. We cross-checked clinically administered diagnosis of PD with prescription refills of antiparkinsonian medications using record linkage. We used the ICD-10 code of G20 in any diagnostic category to find all cases with possible PD. For case certification those patients were considered to have PD who were recorded with G20 code in at least 2 calendar years. For a more conservative estimation we determined the number of those who also refilled antiparkinsonian medication.

Results: Between 2010 and 2012 there were 46,383 subjects with certified PD by clinical criteria. Crude and age-standardized incidence were 49/100,000/year (95% CI: 45–53), and 56/100,000/year (95% CI: 51–60). Crude and age standardized prevalence rates were 404/100,000 (95% CI: 392–416) and 471/100,000 (95% CI: 456–485). Of all clinically certified PD patients 72% refilled antiparkinsonian medications.

Discussion: The incidence and prevalence of PD in Hungary is higher than earlier estimates, which should be considered in organizing healthcare services for this patient group.

Use of Fall-Risk Inducing Drugs in Patients Using Anti-Parkinson Drugs (APD): A Swedish Register-Based Study

Objectives

Many drugs increase the risk of falls in old age. Although persons with Parkinson’s disease (PD) are at increased risk of experiencing falls and fractures, the use of fall-risk inducing drugs (FRIDs) in this population has not previously been investigated. The objective of this study was to investigate the burden of use of FRIDs in older persons treated with anti-Parkinson drugs (APD; used as a proxy for PD), compared to persons without APD.

Methods

We analyzed individual data on age, sex, type of housing and drug use in 1 346 709 persons aged ≥ 65 years in the Swedish Prescribed Drug Register on the date of 30 September 2008. Main outcome measure was the use of FRIDs.

Results

FRIDs were used by 79% of persons with APD and 75% of persons without APD. Persons with APD were more likely to use ≥ 1 FRIDs compared to persons without APD (adjusted OR: 1.09; 95% CI: 1.06-1-12). The association was stronger for concomitant use of ≥ 5 FRIDS (adjusted OR: 1.49; 95% CI: 1.44–1.55).

Conclusions

The high use of FRIDs among persons with APD indicates that these patients may be at increased risk of drug-induced falls. Further studies are needed to investigate how these drugs affect the risk of falling in persons with PD.

Parkinson's disease and occupation: differences in associations by case identification method suggest referral bias

METHODS

We used a population-based sample of 403 Parkinson's disease cases and 405 controls to examine risks by occupation. Results were compared to a previous clinic-based analysis.

RESULTS

With censoring of jobs held within 10 years of diagnosis, the following had significantly or strongly increased risks: social science, law and library jobs (OR = 1.8); farming and horticulture jobs (OR = 2.0); gas station jobs (OR = 2.6); and welders (OR = 3.0). The following had significantly decreased risks: management and administration jobs (OR = 0.70); and other health care jobs (OR = 0.44).

CONCLUSIONS

These results were consistent with other findings for social science and farming occupations. Risks for teaching, medicine and health occupations were not elevated, unlike our previous clinic-based study. This underscores the value of population-based over clinic-based samples. Occupational studies may be particularly susceptible to referral bias because social networks may spread preferentially via jobs.

Incidence and mortality of Parkinson's disease in older Canadians

OBJECTIVE

To estimate the age-specific incidence of Parkinson's disease (PD) in elderly persons in the Canadian province of British Columbia (BC). All-cause and injury mortalities and relative risk of death for those persons with PD were also examined.

METHODS

A historical cohort study was conducted using 5 provincial administrative databases from 1991/92 to 2000/2001. A series of algorithms based on the databases were created for case ascertainment of PD for persons 65 years or older. Crude and age-specific incidence and mortality rates were calculated using person-years of follow-up as the denominator. The impact of PD on all-cause and injury mortalities was examined using multivariate Cox regression models to provide adjusted hazard ratios.

RESULTS

10,910 incidence cases over 6,051,682 person-years of follow-up were identified. The crude annual incidence rate was 252 per 100,000 person-years. Over the nine year period, age standardized incidence for males ranged from 207 to 396 per 100,000 person-years and 127 to 259 per 100,000 person-years for females. Persons with PD were at a 43% greater risk of all-cause mortality and specifically, 51% greater risk of injury mortality.

CONCLUSIONS

Incidence of PD is substantially higher in advanced age with age adjusted increases for both all-cause and injury mortalities. These findings also highlight falls as a primary factor for injury mortality in PD.