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.

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.

Researchers at the First Affiliated Hospital of Dalian Medical University investigated survival among 218 Parkinson’s patients being followed at their clinic.

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.

“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.”.

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.