Clinimetric approach to rating scales for the assessment of apathy in Parkinson's disease: A systematic review

A number of rating scales for the assessment of apathy in Parkinson's disease (PD)were developed. Unfortunately, previous studies focused mainly on psychometric criteria rather than on clinimetric principles to develop these assessment instruments. In the clinimetric approach, the clinical validity of a rating scale, rather than its statistical significance, has the priority. The aim of the present systematic review was to capture the clinimetric properties of these rating scales and to identify the measures, which display clinical validity for the assessment of apathy in PD. The systematic search was conducted on Scopus, PsycINFO, PubMed, Web of Science, ScienceDirect, and Medline following the PRISMA guidelines. A total of 44 studies were included and analyzed in this systematic review. The apathy rating scales, which were found to be psychometrically robust and reliable, were actually clinically questionable. The apathy measures, which displayed clinimetric properties, were the Starkstein Apathy Scale (SAS), the 5-item version of the World Health Organization Well-Being Index (WHO-5), the Neurasthenia Scale and the Lille Apathy Rating Scale (LARS). The SAS was found to be clinically valid at a macro-analytic level, particularly when used either to exclude the presence of symptoms of apathy or to evaluate the side effects of medications. The WHO-5 and the Neurasthenia Scale were found to be clinically valid only at a micro-analytic level and can be used as screening measures for the assessment of the severity of symptoms of apathy. The LARS was a clinically valid instrument to be used for the diagnosis of apathy.