Cohort Study on Patient Outcomes, Effectiveness and Cost-effectiveness of Intervention Programmes for DM/HT Patients

Cohort Study to Investigate the Outcomes of Patients With Hypertension and/or Diabetes Mellitus and the Effectiveness and Cost-effectiveness of Structured Multi-disciplinary Intervention Programmes

Objectives: To determine the outcome trajectories of patients with hypertension (HT) and/or diabetes mellitus (DM), and evaluate the long-term effectiveness and cost-effectiveness of the Risk Assessment and Management Programmes (RAMP) and other primary care services such as Patient Support Call Centre (PSCC) on reducing complications and mortality

Design: Population-based cohort study

Setting: Hospital Authority (HA) primary care clinics Participants: All patients aged ≥18 years with DM or HT managed in HA primary care clinics between 2006 and 2021

Main outcome measures: (1) incidence of DM/HT-related complications (cardiovascular disease, end-stage renal disease, retinopathy, neuropathy and all-cause mortality); (2) service utilization (out-patient clinics, Accident and Emergency and overnight hospitalizations); (3) Incremental cost-effectiveness ratio per complications or all-cause death avoided, and per QALY gained by RAMP or PSCC.

Methods: A naturalistic cohort study (maximum 10-year follow-up) and retrospective data extraction from the HA clinical management system (CMS) database will be conducted to identify and correlate outcome trajectories of HT and/or DM patients with personal, service delivery and process of care factors. Outcomes of propensity score matched cohorts who have and have not participated in the programmes will be compared. Multivariable Cox proportional hazards regression and Poisson/negative binomial regression will be conducted to evaluate the effect of RAMP, PSCC and other primary care services on the risk of complications, mortality and service utilization. Empirical costs and effectiveness data will be used to calculate cost-effectiveness from the provider's perspective.

Significance: Findings will inform how to optimize service delivery for HT/DM patients in Hong Kong

A naturalistic cohort study with a maximum follow-up period of 10 years, and retrospective extraction of relevant data from the HA clinical management system (CMS) database, designed as four sub-studies:-

1. A trajectory study on all HA primary care patients with HT and/or DM receiving care from 2006 to 2019, to explore the trajectory patterns for clinical, treatment and complication profiles and investigate the impact of multi-morbidity, continuity-of-care, different service delivery models and management strategies (including investigation frequency and specific drug regimens) on outcomes and health service utilization.
2. A 10-year effectiveness and cost-effectiveness analysis (CEA) of RAMP-DM. A cohort of RAMP-DM patients will be compared against a propensity score matched cohort of 'usual care' only DM patients to determine the effectiveness and cost-effectiveness of RAMP-DM on reducing complications and mortality and gain in quality adjusted life years (QALY). The optimal criteria and frequency of repeating RAMP-DM will be determined.
3. A 10-year effectiveness and CEA of RAMP-HT. A cohort of RAMP-HT will be compared against a propensity score matched cohort of 'usual care' only HT patients to determine the effectiveness and cost-effectiveness of RAMP-HT on reducing complications and mortality and gain in QALY. The optimal criteria and frequency of repeating RAMP-HT will be determined
4. An evaluation on the effectiveness and cost-effectiveness of PSCC. A cohort of RAMP-DM plus PSCC (RAMP-DM+PSCC) will be compared against a propensity score matched cohort of RAMP-DM only patients to evaluate the effectiveness and cost effectiveness of PSCC on the reduction of complications and mortality and gain in QALY.

Inclusion Criteria:

(Trajectory study)

• All patients aged 18 years or above with a documented doctor-diagnosed DM or HT between 2006 and 2019.

• Documented management in the HA GOPC or FMC identified from the HA CM database between 2006 and 2019.

  (10-year CEA study on RAMP-DM)

• Documented diagnosis of DM without any known complications on or before September 2010

• Documented management in the HA GOPC and FMC identified from the HA CMS database between 2009 and 2019,

• Patients who attended the first RAMP-DM assessment between August 2009 to September 2010 for inclusion in the RAMP-DM cohort

• Patients who have never attended any RAMP-DM assessment between August 2009 to December 2019 for inclusion in the usual care only cohort

  (10-year CEA study on RAMP-HT)

• Documented diagnosis of HT without DM and any known complications on or before March 2013

• Documented management in the HA GOPC and FMC identified from the HA CMS database between 2011 and 2021,

• Patients who attended the first RAMP-HT assessment between October 2011 to March 2013 for inclusion in the RAMP-HT cohort

• Patients who have never attended any RAMP-HT assessment between October 2011 to December 2021 for inclusion in the usual care only cohort

  (5-year CEA study on PSCC)

• Documented diagnosis of DM without any known complications on or before August 2016

• Documented management in the HA GOPC and FMC identified from the HA CMS database between 2012 and 2021,

• Patients who attended the first RAMP-DM assessment between September 2012 to August 2016

• Patients who received the first PSCC call between September 2012 to August 2016 after the first RAMP-DM assessment for inclusion in the PSCC cohort

• Patients who have never received any PSCC services between September 2012 to December 2021 for inclusion in the RAMP only cohort

Exclusion Criteria:

(applicable to all sub-studies)

• Non-Chinese
• Patients with documented DM/HT-related complications diagnosed before the date of enrolment
• Medical specialist outpatient attendance before or within the first year of inclusion to study, to exclude subjects who might have developed complications before study enrolment