SUMMARY

Introduction

Obesity is a disease defined by an excessive accumulation of fat that affects individuals physically and psychologically, and may also influence their social relationships. In primary care, overweight and obesity are usually assessed through anthropometric studies. These include weight and height measurements to calculate body mass index (BMI), as well as the collection of other parameters, such as waist circumference. In recent years, significant advances have been made in body composition assessment through bioelectrical impedance analysis (BIA); however, its use has so far been mainly limited to hospital care.

Objective

The main objective of this Health Technology Assessment (HTA) report is to evaluate the safety, clinical effectiveness, and cost-effectiveness, as well as the ethical, legal, organizational, and social aspects of using BIA for the assessment of overweight and obesity, in order to inform the decision to include this technology in the common portfolio of services of the Spanish National Health System (SNS) for use in primary care.

Methodology – Effectiveness and Safety

A systematic review (SR) of the published scientific literature was conducted. Searches were performed without date or language restrictions in the following electronic databases: MEDLINE (OVID), Embase (Elsevier), CENTRAL (Cochrane Library-Wiley), CINAHL (EBSCOhost), and Web of Science Core Collection (Clarivate Analytics) up to October 8, 2024. Randomized clinical trials were selected, or, in their absence, non-randomized trials, and if not available, longitudinal observational studies (case-control and cohort studies). Key outcome measures considered were: mortality, quality of life, ischemic heart disease, acute myocardial infarction, stroke, and diabetes mellitus. Risk of bias was assessed using the ROBINS-E tool from the Cochrane Collaboration. Where possible, a quantitative synthesis of results was performed using meta-analysis with Review Manager version 5.4 and R (Comprehensive R Archive Network version 4.2.2). The quality of evidence and the strength of the recommendations were assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology.

Cost-effectiveness and Economic Analysis

The SR included a search for economic evaluations (alongside primary studies or models) reporting any of the following outcomes: incremental cost-effectiveness ratio (ICER), costs expressed in monetary units, and benefits expressed in quality-adjusted life years (QALYs), life years gained (LYG), monetary units, or any of the outcome measures listed in the effectiveness section. Methodological quality was planned to be assessed using the Drummond checklist and/or the FLC 3.0 Critical Appraisal Tool from OSTEBA, along with data extraction and a narrative synthesis of the results. In addition, a partial economic evaluation was conducted to estimate the direct costs associated with BIA from a primary care center perspective. Direct costs for the acquisition, installation, and maintenance of the equipment and specific software were considered. Finally, the gross budget impact of including this technology in the SNS over a five-year time horizon was estimated, assuming one BIA device would be installed in each center (health center or local clinic).

Ethical, Legal, Organizational, and Social Aspects

The scope of the evaluation of these aspects was based on the same population, intervention, and comparison described earlier for the effectiveness and cost-effectiveness evaluation. Searches were conducted in MEDLINE (Ovid), Embase (Elsevier), and CINAHL (EBSCOhost) databases up to September 2024. A narrative synthesis of the results was proposed, considering relevance and consistency criteria.

Results – Effectiveness and Safety

A total of 3,757 unique references were retrieved from the electronic database searches. The effectiveness and safety assessment was based on data from 19 longitudinal studies (sample size: 891,836 patients), published between 1996 and 2024, which analyzed the association between BIA and anthropometric measurements with the risk of future health events (mortality, ischemic heart disease and other cardiovascular events, prostate cancer, kidney disease, asthma, and cataracts). Overall, the quality of the evidence was considered low. No studies were identified that evaluated the key outcomes of quality of life and diabetes mellitus. Regarding BIA results, no significant associations were observed between body fat percentage (BFP, 1 SD increase [5%]), lean mass (LM, 1 SD increase [5 kg]), or fat mass (FM, 1 SD increase [5 kg]) and the key outcomes evaluated. Regarding anthropometric measurement results, several significant associations were found:

• An increase in BMI (1 SD increase, 5 kg/m²) was associated with a 14% increase in the risk of cardiovascular events in general (HR=1.14; 95% CI: 1.02 to 1.28; p=0.02; I²=89%; k=3 studies, 5 cohorts). Specifically, it was associated with an 18% increase in the risk of ischemic heart disease (HR=1.18; 95% CI: 1.06 to 1.32; p=0.003; I²=71%; k=1 study, 3 cohorts) and a 22% increase in cardiovascular events (combined morbidity and mortality measure) (HR=1.22; 95% CI: 1.08 to 1.39; p=0.002; k=1 study).

• An increase in waist circumference (WC; 1 SD increase, 5 cm) was associated with a 0.5% increase in the risk of all-cause mortality (HR=1.05; 95% CI: 1.02 to 1.07; p=0.0006; I²=0%; k=2 studies, 3 cohorts), a 16% increase in the risk of ischemic heart disease (HR=1.16; 95% CI: 1.07 to 1.26; p=0.003; I²=0%; k=1 study, 2 cohorts), and a 21% increase in cardiovascular events (HR=1.21; 95% CI: 1.09 to 1.35; p=0.0006; k=1 study).

• An increase in waist-to-hip ratio (WHR; 1 SD increase, 0.05) was associated with a 10% higher risk of all-cause mortality (HR=1.10; 95% CI: 1.05 to 1.17; p=0.0003; I²=16%; k=1 study, 2 cohorts) and a 16% increase in the risk of ischemic heart disease (HR=1.16; 95% CI: 1.07 to 1.25; p=0.0003; I²=0%; k=1 study, 2 cohorts).

• An increase in waist-to-height ratio (WHtR; 1 SD increase, 0.05) was also associated with higher risk of mortality: 0.8% for all-cause mortality (HR=1.08; 95% CI: 1.04 to 1.12; p<0.0001; I²=0%; k=2 studies, 3 cohorts) and 26% for diabetes-related mortality (HR=1.26; 95% CI: 1.07 to 1.48; p=0.006; k=1 study); as well as a 23% increase in cardiovascular event risk (HR=1.23; 95% CI: 1.21 to 1.25; p<0.0001; I²=0%; k=2 studies, 5 cohorts), 23% for ischemic heart disease (HR=1.23; 95% CI: 1.20 to 1.26; p<0.0001; I²=0%; k=2 studies, 3 cohorts), 22% for stroke (HR=1.22; 95% CI: 1.18 to 1.26; p<0.0001; k=1 study), and 24% for acute myocardial infarction (HR=1.24; 95% CI: 1.21 to 1.27; p<0.0001; k=1 study).

• An increase in skinfold thickness (SFT; 1 SD increase, 5 mm) was associated with a 3% reduction (p=0.01) in all-cause mortality risk (HR=0.97; 95% CI: 0.94 to 0.99; p=0.01; I²=0%; k=3 studies).

Cost-effectiveness and Economic Analysis

The SR did not identify any economic evaluations that met the established criteria. The cost analysis showed that the annual cost would be €1,600 for a health center acquiring a BIA device with the characteristics considered in this analysis. The cost per patient would vary depending on the number of people attended; for example, with 7 patients per week, the cost would be €4.40 per patient. In a scenario including all primary care centers, the gross budget impact for the SNS over five years would be €218,814,851, while if the device were installed only in health centers (excluding local clinics), the impact would be reduced to €51,045,612 over the same period.