Reply: Screening Instruments and Prevalence of Impulse Control Disorders.

Abstract

We appreciate the opportunity to respond to the comments on our recently published study1 and thank Jaakkola and Joutsa2 for their constructive discussion. We agree that the methodology used to detect impulse control disorders (ICDs) is crucial to estimate their prevalence. Overall, most studies included in our review used a screening tool to detect ICDs, thus increasing the sensitivity and yielding higher prevalence rates. We acknowledged this relevant caveat in our study and reported the methodology used in each of the studies selected. A previous study showed that the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (QUIP) and the Minnesota Impulse Disorders Interview (MIDI), the 2 most used screening tools in our sample, yielded overall comparable results.3 Only a minority of studies, both from Western and Eastern countries, relied on clinical interviews to detect ICDs, as we reported.1 Jaakkola and Joutsa2 also raised their concerns about another important issue regarding impulse control behaviors (ICBs), which we did not fully address in our review. As we explained, we chose not to address the prevalence of the different subtypes of ICBs as these data were more inconsistently reported than ICDs. However, as our colleagues pertinently point out, the QUIP assesses both ICDs and ICBs.4 For our review, we used the total prevalence of any ICD as reported in each study, and considering that none of the articles using QUIP specifically states the exclusion of ICBs from the assessment, we should assume that ICBs may be included in the total prevalence reported. In the perfect scenario, all studies would have specified clearly if ICBs were included in the total prevalence reported and subtracted this data from it, but this was not the case for all of them. We accept that this is an important limitation of our study, for ICDs as a whole could be overestimated in several studies included in our analysis, and we appreciate the pertinent observation of Jaakkola and Joutsa. However, this limitation does not affect our data regarding the frequency of each subtype of ICD separately, on which we also based our results. In our study, we acknowledged that the variability in patient populations and methodological differences among the included studies make them difficult to compare directly, and we agree with Jaakkola and Joutsa2 that our results should be interpreted with caution. Even so, our review puts together a large number of studies, showing the huge heterogeneity currently existing in the literature, and points out the relevance of considering geographical differences in the assessment of ICDs in patients with Parkinson's disease. Our research may help to set the basis of more specific studies conducting this complex and multifaceted research. (1) Research Project: A. Conception, B. Organization, C. Execution; (2) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique. P.P.-D.: 1A, 1B, 1C, 2A, 2B A.A.-C.: 1A, 1B, 2A, 2B Ethical Compliance Statement: The authors confirm that the approval of an institutional review board and informed patient consent were not required for this work. 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. Funding Sources and Conflict of Interest: This research did not receive any funding. The authors declare that there is no conflict of interest. Financial Disclosures for the Previous 12 Months: Paloma Parra-Díaz declares no financial disclosures. Araceli Alonso-Cánovas has received honoraria as a speaker from AbbVie, Zambon, Alter, Krka, and Lundbeck. She has participated in the advisory boards of AbbVie, Zambon, and Bial. She has received travel grants from AbbVie and Zambon and funding for scientific research from Italfarmaco.