Survival With Parkinson’s Tied to Age at Onset, Cognition in Study

Survival rates, important to care, analyzed for 218 patients in northern China

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by Andrea Lobo |

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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 in northern China for 10 years found.

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

The researchers were looking specifically to create a standardized mortality ratio (SMR) for patients attending their hospital in Dalian, as no SMR data — of help in both clinical and family care — existed for patients “in the northern Chinese mainland.” Nonetheless, 10-year survival for 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 journal BMC Neurology.

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Currently, four main aspects are thought to affect survival with Parkinson’s: demographics, clinical characteristics, intervention measures, and environmental factors. Older 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 death rate among Parkinson’s patients to a reference population. Some studies in other countries demonstrated regional differences in mortality; for example, studies have suggested that the SMR of patients in the US is higher in its northern than southern regions.

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

Respiratory and heart diseases were common causes of death

These patients (53.2% women) had mean age at disease onset of 57, and had been living with Parkinson’s for a mean of four years when they entered the study. Fatigue was reported by 52.8% of them, and a majority (68.8% or 150 people) also engaged in regular physical “leisure time” exercise.

Over 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 common causes were respiratory diseases (29 patients, 58%), mainly pneumonia (48%), and heart disease (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, analyses showed, amounted to an overall SMR of 1.32.

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

Previous studies set the SMR for Parkinson’s patients in Shanghai, in southern China, at .87, and that for patients in Hong Kong at 1.10, they also noted.

Survival benefit seen for 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 survival for Parkinson’s patients’ — the SMR was 1.13 for patients who underwent surgery during follow-up.

Physical 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 the 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 final 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 above 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.

A later analysis based on multiple variables — called a multivariate analysis, looking at the relationship between several variables — confirmed that older age at onset, a H&Y stage of 3 or greater, and severe cognitive impairment were independent predictors of poorer survival.

Of note, the H&Y scale is used to evaluate functional disability associated with disease progression, with higher staging meaning the loss of more dopaminergic neurons and reduced posture 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 a deterioration in survival,” the researchers wrote.

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

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

A potentially key study limitation, the researchers noted, was that data used came from patients treated at one “specialist clinic rather tha[n] the community.”