Penko 2019.

Study characteristics
Methods	RCT
Participants	Setting: facility, USA N = 21 Sample: recruited from the Cleveland Clinic (Cleveland, Ohio) and the surrounding area (32% women) Age (years): mean (SD) single‐modal group 64.6 (8.5), multimodal group 57.8 (8.2) Inclusion criteria: clinical diagnosis of PD; Hoehn and Yahr stage 2 to 4; at least 2 falls in the prior 12 months; ability to walk a minimum of 300 feet with or without a walking aid. Exclusion criteria: any musculoskeletal contraindication to exercise; a history of neurological disease other than PD; ≥3 errors on the short Portable Mental Status Questionnaire; inability to follow 2‐step commands; uncontrolled cardiovascular risk factors classifying the individual as a high‐risk exerciser as per the American College of Sports Medicine; having undergone any surgical procedure for the treatment of PD (e.g. deep brain stimulation). Disease severity at baseline: HY stage mean (SD) 2.3 (0.5), MDS‐UPDRS motor score mean (SD) 36.6 (11.2)
Interventions	Exercise 1. Exercise: single‐modal training ‐ gait training and cognitive training performed separately (45 minutes, 3x/week for 8 weeks) 2. Exercise: multimodal training ‐ gait training and cognitive training performed simultaneously (45 minutes, 3x/week for 8 weeks) Cognitive training was the same for both groups and involved tasks targeting executive function, attention, memory and language. Gait training was the same for both groups and focused on improving gait quality (e.g. velocity and step length)
Outcomes	1. Rate of falls Other outcomes reported but not included in this review
Duration of the study	12 weeks
Funding source	Davis Phinney Foundation
Notes	Fall data collected: for the past 30 days, measured at 8 weeks (post intervention) and 12 weeks (follow‐up), via recall
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A random component in the sequence generation was described. Quote from Rosenfeldt 2019: "…participants were randomized via a nonreplenished envelope pull into the SMT or MMT group”
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement as a method of concealment is not described.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Participants and intervention (two different exercise and cognitive training interventions) delivery personnel not blinded to group allocation but impact of non‐blinding unclear.
Blinding of outcome assessment (detection bias) Falls and fallers	Unclear risk	Unclear if personnel collecting fall information blinded to group allocation.
Incomplete outcome data (attrition bias) Falls	Low risk	See appendix for method of assessment
Selective reporting (reporting bias)	High risk	The study protocol is available (NCT02538029) but not all the secondary outcomes of interest (quality of life) have been reported in the pre‐specified way. Additionally, falls are reported but are not listed as an outcome in the protocol.
Method of ascertaining falls (recall bias) Falls and fallers	Unclear risk	At baseline and follow‐up there was retrospective recall over 30 days. There was shorter recall during the intervention period, however both post test and follow‐up fall data has been used in the analysis. Quote: "Fall frequency over the past 30 days were assessed via participant recall, and individuals were prompted by study personnel asking, “How many times have you come to rest inadvertently on the ground or other lower level surface in the past 30 days?” and "...participants were asked if a fall occurred at each intervention visit."