Legacy effect of delayed blood pressure lowering drug treatment in middle-aged adults with mildly elevated blood pressure: systematic review and meta-analysis

The long-term benefits of early intensive therapy in chronic diseases-the legacy effect

The 'legacy effect' refers to the long-term benefits of intensive therapy that are observed long after the end of clinical trials and trial interventions in chronic diseases such as diabetes, hyperlipidaemia and hypertension. It emphasizes the importance of intensive treatment to prevent long-term complications and mortality. In chronic kidney disease (CKD), the legacy effect is evident in various studies. Long-term nephroprotection in diabetes is well documented in major studies in the early stages of diabetes, such as Diabetes Control and Complications Trial-Epidemiology of Diabetes Interventions and Complications (DCCT-EDIC), UK Prospective Diabetes Study (UKPDS) and Intensified Multifactorial Intervention in Patients with Type 2 Diabetes and Microalbuminuria (STENO-2). These studies highlight the importance of intensive glycaemic control in reducing microvascular complications, including nephropathy, in patients with recently diagnosed type 1 and type 2 diabetes. However, the legacy effect is less evident in patients with long-term, established diabetes. In chronic glomerulonephritis, studies on immunoglobulin A nephropathy showed that early immunosuppressive treatment could have long-term beneficial effects on kidney function in children and adults with CKD. The Frequent Hemodialysis (FH) and the EXerCise Introduction To Enhance Performance in Dialysis (EXCITE) trials indicated that frequent haemodialysis and a personalized walking exercise program could improve clinical outcomes and reduce the long-term risk of death and hospitalization. The legacy effect concept underscores the importance of intensive intervention in chronic diseases, including CKD. This concept has significant implications for public health and warrants in-depth basic and clinical research to be better understood and exploited in clinical practice. However, its limitations should be considered when interpreting long-term observational data collected after a clinical trial. Appropriate study designs are necessary to investigate an unbiased legacy effect.

Methods to address selection bias in post-trial studies of legacy effects were evaluated

OBJECTIVES

Post-trial follow-up studies have become increasingly important to investigate the long-term effectiveness of interventions after randomized controlled trials (RCTs). Legacy effects refer to intervention effects that are only observed after the trial has ended and are not the direct effects observed during the trial period. However, limited attention has been given to the potential selection bias in post-trial studies.

METHODS

Using directed acyclic graphs, we illustrated potential sources of selection bias in post-trial studies of cardiovascular disease preventative interventions. We constructed scenarios where selection bias was present and undertook simulations to assess the ability of different modeling approaches to correct for this bias: no adjustment, adjustment for trial baseline covariates, adjustment for post-trial covariates and inverse probability weighting (IPW) methods. Using empirical data from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial and post-trial study, we demonstrated application of different modeling approaches.

RESULTS

In the presence of selection bias, modeling without adjustment always resulted in biased estimates. Modeling with adjustment and IPW methods were able to correct the selection bias. The ACCORD study also demonstrated that while the direct effects were potentially beneficial, all models attempting to address selection bias revealed larger potential legacy effects when compared to unadjusted estimates.

CONCLUSION

Post-trial follow-up studies have the potential to provide valuable information for clinical practice by detecting legacy effects. However, it is important to consider and address selection bias that may arise from the post-trial study. This study highlights the importance of using an appropriate analysis method and identifying the potential bias sources to ensure that the findings are reliable and generalizable to the target population.

Long-Term Effect of Weight Regain Following Behavioral Weight Management Programs on Cardiometabolic Disease Incidence and Risk: Systematic Review and Meta-Analysis

BACKGROUND

Behavioral weight management programs (BWMPs) enhance weight loss in the short term, but longer term cardiometabolic effects are uncertain as weight is commonly regained. We assessed the impact of weight regain after BWMPs on cardiovascular risk factors, diabetes, and cardiovascular disease.

METHODS

Trial registries, 11 databases, and forward-citation searching (latest search, December 19) were used to identify articles published in English, from any geographical region. Randomized trials of BWMPs in adults with overweight/obesity reporting cardiometabolic outcomes at ≥12 months at and after program end were included. Differences between more intensive interventions and comparator groups were synthesized using mixed-effects, meta-regression, and time-to-event models to assess the impact of weight regain on cardiovascular disease incidence and risk.

RESULTS

One hundred twenty-four trials reporting on ≥1 cardiometabolic outcomes with a median follow-up of 28 (range, 11-360) months after program end were included. Median baseline participant body mass index was 33 kg/m2; median age was 51 years. Eight and 15 study arms (7889 and 4202 participants, respectively) examined the incidence of cardiovascular disease and type 2 diabetes, respectively, with imprecise evidence of a lower incidence for at least 5 years. Weight regain in BWMPs relative to comparators reduced these differences. One and 5 years after program end, total cholesterol/HDL (high-density lipoprotein) ratio was 1.5 points lower at both times (82 studies; 19 003 participants), systolic blood pressure was 1.5 mm mercury and 0.4 mm lower (84 studies; 30 836 participants), and HbA1c (%) 0.38 lower at both times (94 studies; 28 083 participants). Of the included studies, 22% were judged at high risk of bias; removing these did not meaningfully change results.

CONCLUSIONS

Despite weight regain, BWMPs reduce cardiometabolic risk factors with effects lasting at least 5 years after program end and dwindling with weight regain. Evidence that they reduce the incidence of cardiovascular disease or diabetes is less certain. Few studies followed participants for ≥5 years.

REGISTRATION

URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42018105744.

Legacy in Cardiovascular Risk Factors Control: From Theory to Future Therapeutic Strategies?

In medicine, a legacy effect is defined as the sustained beneficial effect of a given treatment on disease outcomes, even after cessation of the intervention. Initially described in optimized control of diabetes, it was also observed in clinical trials exploring intensification strategies for other cardiovascular risk factors, such as hypertension or hypercholesterolemia. Mechanisms of legacy were particularly deciphered in diabetes, leading to the concept of metabolic memory. In a more discreet manner, other memory phenomena were also described in preclinical studies that demonstrated long-lasting deleterious effects of lipids or angiotensin II on vascular wall components. Interestingly, epigenetic changes and reactive oxygen species (ROS) appear to be common features of “memory” of the vascular wall.

Association between characteristics of behavioural weight loss programmes and weight change after programme end: systematic review and meta-analysis

OBJECTIVE

To determine if the characteristics of behavioural weight loss programmes influence the rate of change in weight after the end of the programme.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Trial registries, 11 electronic databases, and forward citation searching (from database inception; latest search December 2019). Randomised trials of behavioural weight loss programmes in adults with overweight or obesity, reporting outcomes at ≥12 months, including at the end of the programme and after the end of the programme.

REVIEW METHODS

Studies were screened by two independent reviewers with discrepancies resolved by discussion. 5% of the studies identified in the searches met the inclusion criteria. One reviewer extracted the data and a second reviewer checked the data. Risk of bias was assessed with Cochrane's risk of bias tool (version 1). The rate of change in weight was calculated (kg/month; converted to kg/year for interpretability) after the end of the programme in the intervention versus control groups by a mixed model with a random intercept. Associations between the rate of change in weight and prespecified variables were tested.

RESULTS

Data were analysed from 249 trials (n=59 081) with a mean length of follow-up of two years (longest 30 years). 56% of studies (n=140) had an unclear risk of bias, 21% (n=52) a low risk, and 23% (n=57) a high risk of bias. Regain in weight was faster in the intervention versus the no intervention control groups (0.12-0.32 kg/year) but the difference between groups was maintained for at least five years. Each kilogram of weight lost at the end of the programme was associated with faster regain in weight at a rate of 0.13-0.19 kg/year. Financial incentives for weight loss were associated with faster regain in weight at a rate of 1-1.5 kg/year. Compared with programmes with no meal replacements, interventions involving partial meal replacements were associated with faster regain in weight but not after adjustment for weight loss during the programme. Access to the programme outside of the study was associated with slower regain in weight. Programmes where the intensity of the interaction reduced gradually were also associated with slower regain in weight in the multivariable analysis, although the point estimate suggested that the association was small. Other characteristics did not explain the heterogeneity in regain in weight.

CONCLUSION

Faster regain in weight after weight loss was associated with greater initial weight loss, but greater initial weight loss was still associated with reduced weight for at least five years after the end of the programme, after which data were limited. Continued availability of the programme to participants outside of the study predicted a slower regain in weight, and provision of financial incentives predicted faster regain in weight; no other clear associations were found.

STUDY REGISTRATION

PROSPERO CRD42018105744.

A methods review of posttrial follow-up studies of cardiovascular prevention finds potential biases in estimating legacy effects

OBJECTIVES

The objective of the study was to assess the methods used, and potential for bias, in posttrial studies of cardiovascular disease (CVD) where legacy effects may be estimated.

STUDY DESIGN AND SETTING

We undertook a methods review of posttrial studies after randomized controlled trials (RCTs) of interventions to prevent CVD. For each included article, we extracted information on important aspects of the design and analysis of the study, and on the reporting of legacy effects.

RESULTS

Of 2,622 retrieved articles, 46 were included in the review: 13 on blood glucose control, 13 on blood pressure control, and 20 on blood lipid control. The median duration for the RCT and posttrial follow-up studies was 5.0 and 5.7 years, respectively. At least 80% of initial RCT participants were enrolled in the posttrial study in 32 of the reports. Most reports used both linkage to routine administrative data sources and active data collection for the posttrial study. Of the 46 included articles, the authors assessed and reported posttrial covariate balance in 29 and made statistical adjustments in the analysis for potential confounding in 25. Posttrial results were reported separately to overall results (from time of randomization) in 21 articles. Legacy effects were claimed in 19 reports, of which 16 could be justified on the basis of the posttrial results.

CONCLUSION

Posttrial studies may provide valuable information for investigating legacy effects, but better reporting of results is needed to realize their full potential. Robust methods of data collection and analysis may address the risk of selection and confounding biases in posttrial studies.

The Legacy Effect in the Prevention of Cardiovascular Disease

The "legacy effect" describes the long-term benefits that may persist for many years after the end of an intervention period, involving different biological processes. The legacy effect in cardiovascular disease (CVD) prevention has been evaluated by a limited number of studies, mostly based on pharmacological interventions, while few manuscripts on dietary interventions have been published. Most of these studies are focused on intensive treatment regimens, whose main goal is to achieve tight control of one or more cardiovascular risk factors. This review aims to summarise the legacy effect-related results obtained in those studies and to determine the existence of this effect in CVD prevention. There is sufficient data to suggest the existence of a legacy effect after intensive intervention on cardiovascular risk factors; however, this effect is not equivalent for all risk factors and could be influenced by patient characteristics, disease duration, and the type of intervention performed. Currently, available evidence suggests that the legacy effect is greater in subjects with moderately-high cardiovascular risk but without CVD, especially in those patients with recent-onset diabetes. However, preventive treatment for CVD should not be discontinued in high-risk subjects, as the level of existing evidence on the legacy effect is low to moderate.