Evaluation of long-term effectiveness and cost-effectiveness of the risk assessment and management programme : diabetes mellitus of the Hospital Authority in Hong Kong

Abstract

Diabetes mellitus (DM) is a global threat in public health due to its increasing prevalence and associated burden. In 2009, the Hospital Authority launched a multidisciplinary, risk-stratified, protocol-driven and individualized intervention programme, the Risk Assessment and Management Programme – Diabetes Mellitus (RAMP-DM), to enhance the quality of DM care in primary care in Hong Kong. The objective of this thesis is to evaluate the long-term effectiveness and cost-effectiveness of RAMP-DM, compared with the usual care.

This research was divided into five parts. First, a literature review on existing multidisciplinary interventions on DM was performed to appraise components in the interventions and methodologies of assessing cost-effectiveness. Second, a longitudinal, retrospective, propensity-score matched cohort study was conducted to evaluate the effectiveness of RAMP-DM in terms of incidence of complications and all-cause mortality over a ten-year observation period. Third, the ten-year direct medical costs incurred by public healthcare service uses were compared between RAMP-DM participants and usual care patients, and ten-year cost-effectiveness of RAMP-DM was then evaluated. Fourth, a landmark analysis was conducted to investigate the cost-effectiveness of repeating RAMP-DM assessment by stratifying the cohort by the frequency of repeating assessment in the first five years after enrollment: 1) > twice (more than biennially), 2) twice (biennially), or 3) < twice (less than biennially). Incidence of complications and mortality, and direct medical costs associated with public healthcare service uses were compared in the latter five-year period. Lastly, a Markov, patient-level simulation was performed to estimate the lifetime cost-effectiveness of RAMP-DM, by using the ten-year effectiveness and cost-effectiveness estimates as model parameters.

A total of 36,746 DM patients without existing complications (18,373 patients in each RAMP-DM and usual care group) were included in the cohort analysis. Over a median observation period of 9.5 years, RAMP-DM participants were observed to have 43% and 55% relatively lower risk in incidence of complications and all-cause mortality, respectively. The ten-year RAMP-DM cost, composed by the costs for set-up, provision of interventions and administration, was HK$2,568 per participant. For direct medical costs incurred by utilization of public healthcare services, RAMP-DM participation was associated with a saving of HK$84,804 per person over ten years, attributed by the reduced use of secondary and tertiary healthcare services. Overall, HK$82,236 could be saved for every DM patient managed by RAMP-DM in addition to usual care, compared with usual care only. Compared with participants who had repeated RAMP-DM assessment < twice within the first five years, those who had repeated > twice and twice had lower incidences of complications (21%-32%) and mortality (31%-40%), and savings of direct medical costs (29.2%-29.5%). Over a lifetime horizon, RAMP-DM was estimated to have saved HK$23,294 and gained 0.89 quality-adjusted life years per DM patient, when compared with usual care only.

RAMP-DM in addition to usual care was a cost-saving approach to manage patients with type 2 DM in public primary care over ten years. Repeating RAMP-DM assessment at least biennially is recommended since it was associated with lower incidence of complications and mortality, and less public direct medical costs.