Effectiveness of a low-intensity telephone counselling intervention on an untreated metabolic syndrome detected by national population screening in Korea: a non-randomised study using regression discontinuity design

Abstract

ObjectiveWhether low-intensity telephone-counselling interventions can improve cardiometabolic risk factors in screen-detected people with metabolic syndrome (MetS) is unclear. The aim of this study was to evaluate the effectiveness of a low-intensity, telephone-counselling programme on MetS implemented by the National Health Insurance Service (NHIS) of Korea using regression discontinuity design.DesignA nationwide non-randomised intervention study with a regression discontinuity design. A retrospective analysis using data from NHIS.SettingNHIS, Korea from January 2011 to June 2013.Participants5 378 558 beneficiaries with one or more MetS components by NHIS criteria detected by population screening were enrolled in the NHIS MetS Management Programme in 2012. Of these, 1 147 695 underwent annual follow-up examinations until June 2013 (‘control group’ which received control intervention, n=855 870; ‘eligible group’ which was eligible for counselling, n=291 825; ‘intervention group’ which participated in telephone counselling among eligible groups, n=23 968).Main outcome measuresAbsolute changes in MetS components, weight and body mass index (BMI) were analysed. Multiple regression analyses were applied using the analysis of covariance model (baseline measurements as covariates).ResultsLow-intensity telephone counselling was associated with decreased systolic BP (−0.85 mm Hg, 95% CI −1.02 to −0.68), decreased diastolic BP (−0.63 mm Hg, −95% CI −0.75 to −0.50), decreased triglyceride (−1.57 mg/dL, 95% CI −2.89 to −0.25), reduced waist circumference (−0.09 cm, 95% CI −0.16 to −0.02), reduced weight (−0.19 kg, 95% CI −0.24 to −0.15) and reduced BMI (−0.07 kg/m2, 95% CI −0.09 to −0.05), when comparing the intervention and control groups. When individuals with low high-density lipoprotein cholesterol were analysed, the intervention was also associated with increased HDL cholesterol (0.90 mg/dL, 95% CI 0.51 to 1.29).ConclusionsLow-intensity telephone counselling programmes could yield improvements in the following year on blood pressure, lipid profiles, weight and body mass index in untreated patients detected at the population screening. However, the improvements may be very modest and the clinical relevance of these small improvements may be limited.

Advancing Quality Improvement with Regression Discontinuity Designs

“…Regression discontinuity designs (RDDs) are an underused methodology in healthcare research that can overcome the limitations of traditional improvement science designs (11). A search of PubMed and the Cochrane Library (performed on May 11, 2017) for the term regression discontinuity yielded only four studies that prospectively applied a healthcare quality improvement intervention using RDD (12)(13)(14)(15). We believe that RDDs are a tool that should be used more widely because they help answer a key question: Did a program really change outcomes for patients?…”

Regression Discontinuity for Causal Effect Estimation in Epidemiology

“…Although application of the regression discontinuity design in epidemiology remains rare [ 11 •], there have been several recent examples in the epidemiologic literature. Examples include the effect of relative younger age compared to their peers at entry to school on suicide [ 29 ], low-intensity telephone counseling on detection of metabolic syndrome [ 30 ], increased schooling on HIV status [ 31 ], human papillomavirus (HPV) vaccination on sexual behavior [ 32 ] and cervical dysplasia [ 33 ••], and the efficacy of prostate-specific antigen screening for detection of prostate cancer [ 10 ••]. These studies, reviewed below, report a range of practices in terms of discussion of the assumptions required for identification of causal effects and in their use of the CACE.…”

“…Yi et al [ 30 ] present results for the effect of a telephone counseling intervention on untreated metabolic syndrome. Enrollees in the NHIS Metabolic Syndrome Management Programme were considered high risk if they had three or more metabolic syndrome criteria, whereas those with two or fewer were considered low risk.…”