Background: Multimorbidity is a global health challenge. Individuals with multimorbidity are frequent users of healthcare services, and many experience fragmented healthcare. We assessed the number of outpatient trajectories and contacts with hospital outpatient clinics for individuals with multimorbidity and explored different time intervals for the occurrence of concurrent outpatient trajectories.
Methods: A population-based cohort of 1.3 million residents, ≥ 18 years, with multimorbidity was identified through Danish national health registries. Multimorbidity was defined as having two or more of 39 specific chronic conditions. Nine disease system categories were used to categorize outpatient contacts in 2018 into outpatient trajectories and trajectory-related contacts. We defined an “outpatient trajectory” as two contacts within 12 consecutive months for the same medical condition. All outpatient contacts and trajectories with related contacts were counted for 2018. The impact of different time intervals on the number of concurrent trajectories was analyzed.
Results: On 1 January 2019, 29% of the adult Danish population was classified as multimorbid. During 2018, 68% of them had ≥ 1 outpatient contact (median: 2 (IQI: 0– 4)). Twenty-six percent had ≥ 1 outpatient trajectory. The median number of trajectory contacts was 3 (IQI: 2– 5). The 4% of individuals with ≥ 2 outpatient trajectories accounted for 28% of trajectory contacts. During the 6-week period from the latest outpatient contact, 33% of all patients with ≥ 2 trajectories in 2018 experienced concurrent trajectories with outpatient contact.
Conclusion: Two-thirds of adult Danes with multimorbidity attended an outpatient clinic in 2018, and one-fourth had at least one outpatient trajectory. Individuals with two or more trajectories represented 4% and comprised 28% of the trajectory contacts; 33% had concurrent trajectories within a 6-week period. It appears that a small proportion place demands on outpatient clinics because of frequent attendance. A more uniform way of organizing outpatient trajectories for these patients merits consideration.

Keywords: outpatient, hospital, multimorbidity, prevalence, healthcare utilization, trajectory