Comment on: The Most Bothersome Aspects of Off Periods Reported by Individuals with Parkinson's Disease

We read with interest the excellent work by Chahine et al,¹ and we brought some information. We congratulate the exposition on the importance of open questions in the modern medicine world and we agree with the authors. Wearing off questionnaires (WOQ) for 19 (WOQ19) and 9 items (WOQ9) have been recommended to screening wearing off (WO) by the Movement Disorder Society. ² In a previous systematic review, it was demonstrated that both questionnaires have excellent sensibility, and at least the WOQ19 has a good specificity. ³ As stated by the authors “the WOQs have been used in several studies to quantify symptom burden and examine the relationship between off symptoms, disease severity, and QOL.” Some data allow us to infer WOQ19 quantitative properties through construct validation. It has been reported the number of positive WO items increases as longer the disease duration and correlates with quality of health. ⁴ Somehow, the number of positive WO items are important because it has been reported that a 2‐items cut‐off has better accuracy in WOQ19. ³ , ⁵ It seems to discriminate differences in quality of life associated with motor and non‐motor WO symptoms. ⁶ There may be some WO manifestations that are not captured by the questionnaire because it came from expert opinion. WOQ19 was a short version from the initial 32‐item questionnaire. In the initial sample, with 13 of the 19 items, it was supposed to capture all patients with WO. ⁷

We agree with Chanine et al.¹ that caution must be taken when using the questionnaires in a clinical setting, because the most bothersome aspects might not be captured. However, the questionnaire can bring some aspects to clinical attention such as non‐motor or subtle manifestation. ⁷ In clinical research, we believe both WOQ19 and WOQ9 questionnaires can be used for screening, and WOQ19 can be used to diagnose because of its accuracy. Even if it does not capture the most bothersome symptoms, it seems to capture other co‐occurring WO symptoms, because its sensitivity is ~90%. ³ We believe it also has some quantitative properties that should explored with more studies. In conclusion, as more papers are published, we can will have a better vision of the clinic metric properties of WOQ as a screening tool and if it works as a scale. Some limitations on individual items analyses must always be kept in mind.

Author Roles

(1) Research Project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript: A. Writing of the first draft, B. Review and Critique.

C.E.M.: 1A, 1B, 1C, 3A, 3B

C.R.d.M.R.: 1C, 3C

Disclosures

Ethical Compliance Statement: We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. The authors confirm that the approval of an institutional review board was not required for this work.

Funding Sources and Conflict of Interest: Carlos R. de Mello Rieder received a grant from the Brazilian National Council for Scientific and Technological Development (CNPq). The authors declare no conflict of interest.

Financial Disclosures for the Previous 12 Months: The authors have no additional disclosures to report.