The impact of gender‐specific survival on the incidence of dementia in Parkinson’s disease ‐ A cohort analysis of Parkinson’s disease patients in German health claims data for the years 2006 to 2017

Abstract

AbstractBackgroundThe aim of our study is to analyze gender‐specific patterns of Parkinson’s disease dementia (PDD) incidence. In addition, we are investigating the extent to which gender differences in survival after initial Parkinson’s disease (PD) diagnosis influence differences in PDD risk among PD patients.MethodWe used a random sample of German longitudinal health claims data of persons at ages 65 years or older (2006‐2017). We identified incident PD cases who were followed‐up for a PDD diagnosis or death. We computed age‐ and gender‐specific PDD incidence rates, death rates, and cumulative PDD incidence functions with death as competing risk. In addition, we performed Cox regression models and Fine and Gray competing‐risk regression models, considering death as a competing event, to calculate PDD hazard ratios (HR), adjusted for important risk factors such as age at PD onset, PD severity in terms of modified Hoehn&Yahr (HY) scale, comorbidities, and medications.ResultOf 2,195 incident PD cases, 602 people died and 750 people received a dementia diagnosis by the end of 2017. 44% of PD men and 45% of PD women had received a dementia diagnosis, 45% of PD men and 32% of PD women had died, and only 11% of PD men but 23% of PD women had survived without a PDD diagnosis. PDD risk among PD patients differs by gender when controlled for age at onset, severity of PD, comorbidities and medications, with men having a higher PDD risk than women (HR = 1.18, p = 0.029). When accounting for death, men and women do not differ regarding their PDD risk (HR = 1.02, p = 0.770). Gender‐specific analyses showed significant age and severity effects in women (Age: HR = 1.05, p<0.001, HY 0‐2.5: reference, HY 3‐5: HR = 1.46, p = 0.011), but not in men.ConclusionWe found that older age at first PD diagnosis and higher disease severity increase PDD risk, but this association is attenuated for PD men when we consider death as a competing risk. This implies that the most frail PD men die rapidly before receiving a dementia diagnosis, whereas women with PD survive at higher rates than men, regardless of their age at onset and disease severity.