Threshold for Quick Diagnosis of Sleep Issues in PD

Pauline Anderson

June 23, 2015

BERLIN, Germany — German researchers have come up with a quick and easy way to determine a need for referral for serious sleep problems in patients with Parkinson's disease (PD).

They have determined that a score of 18 or above on the Parkinson's Disease Sleep Scale-2 (PDSS-2) indicates sleep-related issues severe enough for referral to a specialist, according to Maria-Lucia Muntean, MD, PhD, Paracelsus Elena Klinik, Kassel, Germany.

The cutoff of 18 on the PDSS "will allow clinicians to easily evaluate sleep problems in PD patients and to decide quickly whether further investigations are needed in order to determine the exact nature of the sleep disturbance," said Dr Muntean.

She presented her study here at the Congress of the European Academy of Neurology (EAN).

Time Constraints

From 60% to 98% of patients with PD experience some sleep problems, including insomnia, sleep fragmentation, sleep apnea, restless legs syndrome (RLS), and daytime sleepiness, the authors note. Such problems can seriously affect quality of life.

Clinicians can evaluate patients with PD for sleep problems through a detailed interview, but time and financial constraints limit doing this use in everyday practice, said Dr Muntean.

Several questionnaires evaluate sleep in patients with PD, including the Pittsburgh Sleep Quality Index (PSQI) and the PDSS-2. The PDSS-2 includes 15 questions, each with a value of 0 to 4 for a maximum total score of 60.

The study included 93 patients (52 men and 41 women) with idiopathic PD who were inpatients at the movement disorders clinic at the Paracelsus Elena Hospital Kassel, Germany, and were enrolled consecutively from December 2013 to February 2014.

The analysis included only inpatients because, as Dr Muntean explained, it was important for physicians to observe the patients directly.

The mean patient age was just over 69 years. While all patients had Hoehn and Yahr stages 1 to 5, more than half were stage 3 to 4. The patients continued to take their regular PD medication.

Two Questions

All patients completed the PDSS-2. The attending physician answered two questions:

  1. Does the patient suffer from sleep problems which are not related to Parkinson's disease (for example, sleep onset or sleep maintenance problems, daytime somnolence)?

  2. Does the patient suffer from Parkinson specific sleep disorders in the night (for example, REM behavior sleep disorder, RLS, tremor, akinesia)?

If the answer was "yes," the physician then classified the sleep problem as mild, moderate, or severe.

The researchers found that 56.98% of patients were considered to have sleep problems not related to PD, while 62.26% patients were deemed to have sleep problems related to PD.

The statistical analysis showed that 83% of patients with a PDSS-2 total score of 18 or more had clinically relevant sleep disturbances compared with 33% of the patients who had a score of less than 18.

PDSS-2 scores were positively related to the severity of the sleep problems, added Dr Muntean.

The results suggest that a score of 18 or more "represents an optimal combination of sensitivity and specificity" to constitute a "cutoff" warranting referral to a sleep specialist or center specializing in sleep disorders, she said.

This is, to Dr Muntean's knowledge, the first time that researchers have determined a cutoff for sleep problems in European patients with PD. Japanese researchers came up with evidence that a PDSS-2 score higher than15 indicated a poor sleeper.

The different cutoff was due to the Japanese researchers' correlating the PDSS-2 total scores with those of the PSQI and not to a questionnaire completed by a clinician. However, the cutoffs might not be that different.

"If we take into account that the PDSS-2 total scores vary between 0 and 60, the cutoff values from the two studies could be considered similar," said Dr Muntean. "Due to ethnic and sleep habit differences, it's difficult to make a one-to-one comparison between the European and Japanese PD population."

Session co-chair Claudio Bassetti, MD, professor and chair, Department of Neurology, University Hospital (Inselspital), Bern, Switzerland, questioned how physicians actually answered the "crucial" questions upon which the prediction depends. "How did they get the answer to those questions at the end of workup? Was it just based on clinical judgment?"

Dr Muntean replied that the attending physicians were expert in movement disorders and had the opportunity to observe the patients for a few days and to interview them, before determining the presence and severity of sleep problems.

Dr Muntean has disclosed no relevant financial relationships.

Congress of the European Academy of Neurology (EAN). Abstract 01226. Presented June 20, 2015.

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