Parkinson’s survival linked to age at onset, cognition in a Chinese study | Survival rates of importance to patient care

Older age at onset, a faster rate of disease progression and severe cognitive impairment are key factors in poorer survival rates for people with Parkinson’s disease, a study that followed patients over North China for 10 years.

Fatigue may also be an indicator of poorer survival, while exercise and deep brain stimulation, a surgery to relieve Parkinson’s motor symptoms in selected patients, may help prolong life.

The researchers specifically sought to create a standardized mortality ratio (SMR) for patients attending their hospital in Dalian, as no SMR data (helping both clinical and family care) existed for patients “in the north of mainland China”. However, the 10-year survival of this Parkinson’s group “was not significantly different from that of the general population in China,” the team reported.

The study “Survival in patients with Parkinson’s disease: a ten-year follow-up study in northern China” was published in the magazine BMC Neurology.

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Currently, four main aspects are believed to affect survival with Parkinson’s: demographics, clinical characteristics, intervention measures, and environmental factors. Advanced age at disease onset and cognitive impairment are recognized risk factors for reduced survival.

The standardized mortality ratio is a common indicator for survival analyses; SMR in this study compares the mortality rate among Parkinson’s patients with a reference population. Some studies carried out in other countries demonstrated regional differences in mortality; for example, studies have suggested that the SMR of patients in the US is higher in northern than southern regions.

Researchers at the First Affiliated Hospital of Dalian Medical University investigated the survival of 218 Parkinson’s patients who were being followed in their clinic. The patients, all with idiopathic disease (cause unknown), were recruited between 2009 and 2012 and were followed until May 31, 2021 or their death.

Respiratory and heart diseases were common causes of death

These patients (53.2% female) had an average age at disease onset of 57 years and had been living with Parkinson’s for an average of four years when they entered the study. 52.8% of them reported fatigue and the majority (68.8% or 150 people) also took regular “leisure time” physical exercise.

During 10 years of follow-up, 50 of these 218 people died, 24 men and 26 women, representing 22.9% of the total group. The most frequent causes were respiratory diseases (29 patients, 58%), mainly pneumonia (48%), and heart diseases (seven patients, 14%). Other causes were digestive system disorders (five patients), stroke (four patients), suicide (two), urinary system disorders (one patient) and heat stroke (one patient).

These deaths, the analyzes showed, resulted in an overall SMR of 1.32.

“This survival survey in northern mainland China gave an SMR of 1.32, meaning that the 10-year mortality rate of [Parkinson’s disease] patients is similar to that expected for the general population across the country,” the researchers wrote, noting that “there appears to be no difference in survival between the South and the North.”

Previous studies put the SMR for Parkinson’s patients in Shanghai, southern China, at 0.87, and that of patients in Hong Kong at 1.10, they also noted.

Survival benefit seen from regular exercise, deep brain stimulation

During this study, 90 patients (41.3%) underwent deep brain stimulation surgery, which involves implanting a device to stimulate targeted regions of the brain with electrical impulses.

The researchers identified above-average regular physical exercise and deep brain stimulation as factors that aid in the survival of Parkinson’s patients: the SMR was 1.13 for patients who underwent surgery during follow-up.

Exercise improves motor function and sleep, and delays the motor and cognitive decline associated with Parkinson’s, they noted. At the molecular level, it reduces oxidative stress and inflammation and increases levels of factors that protect brain cells.

“It is speculated that the neuroprotective effect of exercise and its clinical benefits may be the reason for the ultimate prolongation of survival,” the scientists wrote.

In contrast, a higher risk of death was associated with fatigue, older age at disease onset, stage 3 or higher on the Hoehn and Yahr scale (H&Y; this scale assesses Parkinson’s progression and stage 3 marks “moderate bilateral disease”), postural instability. and gait disorders (PIGD; gait characterized by a stooped posture, decreased arm swing, and a shuffling gait), dysphagia (difficulty swallowing), severe cognitive impairment, and poor sleep quality.

Further analysis based on multiple variables, called multivariate analysis, which looks at the relationship between several variables, confirmed that older age at onset, an H&Y stage of 3 or more, and severe cognitive impairment were independent predictors of longer survival poor

Of note, the H&Y scale is used to assess functional disability associated with disease progression, with higher staging signifying loss of more dopaminergic neurons and reduced postural balance.

Overall, “we concluded that older age at onset, higher baseline H&Y staging, and severe cognitive impairment independently predicted a higher risk of death. Fatigue was another indicator that may lead to impairment of survival,” the researchers wrote.

No association was found for factors including a patient’s gender, education, and lifestyle. Similarly, survival was not linked to tremors as an initial symptom, hallucinations, depression or comorbidities.

“Identifying and understanding factors related to survival will provide a new direction for disease-modifying therapy, which is expected to increase the life expectancy of [Parkinson’s] patients,” the team concluded.

A potentially key limitation of the study, the researchers noted, was that the data used came from patients treated in a “specialist clinic rather than[n] the community.”

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