Floris Vlaanderen - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands
Yvonne de Man - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands
Marit Tanke - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands
Marten Munneke - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands
Femke Atsma - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands
Marjan Meinders - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands
Patrick Jeurissen - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands
Bastiaan Bloem - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands
Jesse Krijthe - Department of Intelligent Systems, Delft University of Technology, Delft, The Netherlands
Stef Groenewoud - Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands

Background  Optimal care for Parkinson’s disease (PD) requires coordination and collaboration between providers within a complex care network. Individual patients have personalised networks of their own providers, creating a unique informal network of providers who treat (‘share’) the same patient. These ‘patient-sharing networks’ differ in density, ie, the number of identical patients they share. Denser patient-sharing networks might reflect better care provision, since providers who share many patients might have made efforts to improve their mutual care delivery. We evaluated whether the density of these patient-sharing networks affects patient outcomes and costs. Methods  We analysed medical claims data from all PD patients in the Netherlands between ۲۰۱۲ and ۲۰۱۶. We focused on seven professional disciplines that are commonly involved in Parkinson care. We calculated for each patient the density score: the average number of patients that each patient’s providers shared. Density scores could range from ۱.۰۰ (which might reflect poor collaboration) to ۸۳.۰۰ (which might reflect better collaboration). This score was also calculated at the hospital level by averaging the scores for all patients belonging to a specific hospital. Using logistic and linear regression analyses we estimated the relationship between density scores and health outcomes, healthcare utilization, and healthcare costs.  Results  The average density score varied considerably (average ۶.۷, SD ۸.۲). Adjusted for confounders, higher density scores were associated with a lower risk of PD-related complications (odds ratio [OR]: ۰.۹۰۱; P < .۰۰۱) and with lower healthcare costs (coefficients: -۰.۰۱۸, P = .۰۰۵). Higher density scores were associated with more frequent involvement of neurologists (coefficient ۰.۰۶۸), physiotherapists (coefficient ۰.۰۵۲) and occupational therapists (coefficient ۰.۰۴۸) (P values all <.۰۰۱). Conclusion  Patient sharing networks showed large variations in density, which appears unwanted as denser networks are associated with better outcomes and lower costs.

Patient-Sharing Networks, Density, Parkinson’s Disease