Reductions in the healthcare utilization assessed were observed after enrolment into PCMH. These effects were robust even after adjusting for potential confounders, secular trends and differential changes in healthcare utilization that PCMH study participants and controls might have during the first quarter of Covid-19 outbreak in Singapore.
At ≥4 four quarters post-enrolment, PCMH study participants had sustained reductions of 1.08 polyclinic visits (p<0.001), 0.37 SOC visits (p=0.047), 0.04 ED visits (p=0.013) and 0.02 inpatient admissions (p=0.093) per person-quarter, compared to the quarter before enrolment and controls.
These findings are aligned with previous evaluation studies that also found reductions in SOC visits, ED visits and inpatient admissions associated with PCMH interventions for patients with higher needs.15, 16, 17, 18, 19, 20, 21, 22. Possible mechanisms for reduction in hospital-based healthcare utilization could be explained by the qualitative findings of the larger study. Participants and caregivers reported that they were able to consolidate care at PCMH, as they received comprehensive care at PCMH that was of similar or better quality compared to their previous usual providers. The positive care experience was attributed to the continuity, personalisation and holistic management of care, and a sustained patient-provider relationship. These findings were triangulated by findings reported in other studies. A qualitative study with patients, payers, implementation staff and experts identified that continuity of care and adoption of care plan were amongst high-value elements that reduce healthcare utilization. Another cohort study observed that patients with continuity of care were less likely to have ED visits.
The one-year time lag before significant reductions was also consistent with the literature. A previous randomized controlled trial in the United States found that amongst patients at high risk for hospitalization, non-significant changes were observed in the first year but significant reductions in inpatient admissions and ED visits were observed in the second year. The authors proposed that a period of engagement was needed to develop trust between the care team and the patients, before patients would reduce utilization of other healthcare services.16
This study had various strengths. Firstly, this study used administrative data from a reliable public regional health system to calculate healthcare utilization. This afforded good coverage of the study participants’ healthcare utilization, as public providers are major players in Singapore’s healthcare scene, with public hospitals providing approximately 80% or more of tertiary inpatient services.29 Administrative data also provided an accurate and objective measure that is not affected by recall error or other response biases.
Secondly, this analysis used a difference-in-difference approach. This design enabled assessment of whether enrolment into PCMH was associated with changes in healthcare utilization over time that were statistically different from the secular trend, combining the strengths of a case-control comparison and cohort study.
Thirdly, analysis of quarterly healthcare utilization provided more granular insights compared to commonly-seen measures of yearly healthcare utilization, while retaining sufficient aggregation to tolerate ‘noise’ in the data.
There were also some limitations to this study. Firstly, the controls are matched only on available observables, and hence may not be ideal counterfactuals, as we did not have sufficient data to match on psychological and social needs. Several indicators suggest that PCMH study participants had higher needs than controls. For example, PCMH study participants had significantly fewer polyclinic visits and more inpatient admissions and ED visits at baseline, compared to the controls. The higher inpatient admissions and ED visits at baseline were contributed by increases over 8 quarters or more before enrolment. This points to a prolonged increase in complexity of medical needs rather than an acute crisis episode, and is unlikely to be followed by recovery with usual care. . In addition, PCMH study participants had a higher prevalence of dementia (P:18%; C:6%), which is strongly associated with higher long-term psychosocial needs and healthcare utilization., Accordingly, relative improvements after enrolment into PCMH would likely be larger if compared to a group with more similar needs.
Causal inference of the estimated reduction of polyclinic visits should also be interpreted with caution, since a small, marginally-significant reduction was observed even before enrolment into PCMH (Q−2 dy/dx: 0.24, p=0.076). This reduction occurred with concomitant increases in SOC visits, inpatient admissions and ED visits before enrolment. As ComSA-PCMH enrolled patients with complex care needs, it could be postulated that by the time of enrolment, polyclinic visits might have become inadequate to support the increase in complexity of care needs. Some care substitution with hospital services may have occurred.
In addition, this analysis did not differentiate between avoidable and unavoidable hospital visits. Avoidable visits include those due to social reasons or milder conditions that could be treated in primary care, or due to escalations that could have been avoided if the conditions had been better managed in primary care. As such, the reductions for avoidable visits could be expected to be more pronounced compared to reductions in all hospital visits, as PCMH is expected to reduce hospital visits via improved management of ambulatory-care sensitive conditions as well as consolidation and coordination of care.15 This can be assessed in future research to improve understanding of the mechanisms that contributed to the reductions in health utilization.
Lastly, this analysis assessed healthcare utilization in a limited time period post-enrolment. Our findings suggest that a longer follow-up period may allow us to capture more comprehensive effects.