Response to the letter by Scorza et al

Abstract

We appreciate the letter from Dr Scorza and his colleagues regarding our recently published article "The increasing prevalence of Parkinson's disease (PD) in Estonia." 1 We read with great interest the papers cited in this letter that investigate the comorbidity and mortality of PD, paying a special attention to the cardiac abnormalities, in particular, the sudden unexpected death in PD (SUDPAR).Based on the World Health Organization reports, the increase in mean life expectancy at birth for Estonian people has been remarkable, rising from 70.8 years in 2000 to 77.6 years in 2015. The shift towards longer life expectancy has increased more rapidly in Estonia than in the European region in general where the above-mentioned indicator has risen from 73 years in 2000 to 77.1 years in 2015. 2 As already discussed in our recent article on PD prevalence in Estonia, the moderately higher frequency of PD at present compared to the demographic situation 20 years ago might be significantly influenced by the higher proportion of elderly people. Our epidemiological study on PD in Estonia encompasses the prevalence, incidence and mortality of the disease. The yet unpublished data show that the incidence has not significantly changed over two decades supporting the influence of longer survival of people to the increased prevalence of the disease.With increasing proportion of elderly population, the disease burden of morbidities associated with ageing is going to rise as well. Older age is associated not only with the higher prevalence of PD, but also with other diseases including cardiovascular, gastrointestinal and oncological disorders. 3,4 Our earlier cross-sectional study on the healthrelated quality of life of patients with PD showed that women have statistically higher load of comorbidities compared to men, including a significantly higher rate of cardiovascular diseases. 5 Although the causes of morbidity and mortality are shown to be similar in the general population and in the PD population, it has been shown that the survival is shorter among PD patients. 6 Higher burden of comorbidities has shown to be a predictor of death in PD patients. 7 Our study analysing the death certificate data of 168 PD patients in the period of 2010-2017 showed that the three most common primary causes of death were cardiovascular diseases (61%), cerebrovascular disorders (14%) and malignant neoplasms (12%). Surprisingly, sudden cardiac death was not registered in any of the death records. ACK N OWLED G M ENT