Assessment of Parkinson’s disease levodopa-induced dyskinesia: a qualitative research study William R. Lenderking • Sally Mannix • Jennifer Petrillo • Christopher Kenney • Amanda Landrian • Anette-Eleonore Schrag Accepted: 15 January 2015 Ó Springer International Publishing Switzerland 2015 Abstract Background and objectives The 26-item Parkinson disease dyskinesia scale (PDYS-26) was developed to assess the im- pact of Parkinson’s disease levodopa-induced dyskinesias (PD-LID). The purpose of this qualitative research study was to assess the content validity of the PDYS-26 in an indepen- dent sample and to use the findings to suggest a conceptual framework around the impact of PD-LID. Methods PD patients experiencing LID and their care- givers were recruited from four US clinical sites. Stage I involved 22 qualitative concept elicitation interviews with patients and caregivers, and 11 qualitative cognitive in- terviews (CI) with patients about the PDYS-26. The PDYS- 26 was modified based on Stage I findings. Stage II con- sisted of 13 CI on the Modified PDYS. Results Forty-six participants were interviewed across both stages of the study. Patient mean age was 67.3 (SD ± 9.55) years; 19 (54.3 %) female; 34 (97.1 %) white. The content validity of the PDYS-26 was generally supported. A revised conceptual framework with three hypothesized domains (body control, activities of daily living, social consequences) was developed. Modifications were made to the PDYS-26 (i.e., emphasizing LID in the instructions; response scale modifi- cation; deleting or modifying items), which resulted in the 22-item Modified PDYS. Conclusions Stage I and II findings suggested a number of modifications to the scale in order to improve the content validity. Psychometric testing of the revised scale with a larger patient sample is suggested to evaluate item per- formance, establish scoring, and provide quantitative sup- port for the conceptual framework. Keywords Parkinson’s disease Á Levodopa Á Levodopa- induced dyskinesia Á Patient-reported Outcomes Á Qualitative research Introduction Parkinson’s disease (PD) is a progressive, neurodegenerative disorder resulting in motor and cognitive impairments [1, 2], including muscle rigidity, tremor, bradykinesia and, in ex- treme cases, akinesia [3]. Although levodopa (L-dopa) re- mains the most effective drug for PD treatment [4], long- term use is complicated by disabling dyskinesias. [2, 5] L-dopa-induced dyskinesias (LID) are involuntary move- ments associated with peak levels of L-dopa following dos- ing, which develop after roughly 5–7 years of treatment in 40–50 % of patients [6–9]. LID are unpleasant and negatively affect quality of life to the degree that patients may delay treatment to avoid developing LID [10, 11]. The impact of LID on PD patients’ lives underscores the need for a valid, reliable measure for use in research and clinical practice; however, measurement of PD-LID has significant challenges [12]. W. R. Lenderking (&) Evidera, 430 Bedford Street, Suite 300, Lexington, MA, USA e-mail: william.lenderking@evidera.com S. Mannix Á A. Landrian Evidera, Bethesda, MD, USA J. Petrillo Novartis AG, Basel, Switzerland C. Kenney Formerly Novartis Pharmaceuticals Corp., East Hanover, NJ, USA A.-E. Schrag University College London, London, UK 123 Qual Life Res DOI 10.1007/s11136-015-0925-7