Brief Interventions In Primary Care Research Articles

Testing the effects of brief intervention in primary care for problem drug use in a randomized controlled trial: rationale, design, and methods

BackgroundA substantial body of research has established the effectiveness of brief interventions for problem alcohol use. Following these studies, national dissemination projects of screening, brief intervention (BI), and referral to treatment (SBIRT) for alcohol and drugs have been implemented on a widespread scale in multiple states despite little existing evidence for the impact of BI on drug use for non-treatment seekers. This article describes the design of a study testing the impact of SBIRT on individuals with drug problems, its contributions to the existing literature, and its potential to inform drug policy.Methods/designThe study is a randomized controlled trial of an SBIRT intervention carried out in a primary care setting within a safety net system of care. Approximately 1,000 individuals presenting for scheduled medical care at one of seven designated primary care clinics who endorse problematic drug use when screened are randomized in a 1:1 ratio to BI versus enhanced care as usual (ECAU). Individuals in both groups are reassessed at 3, 6, 9, and 12 months after baseline. Self-reported drug use and other psychosocial measures collected at each data point are supplemented by urine analysis and public health-related data from administrative databases.DiscussionThis study will contribute to the existing literature by providing evidence for the impact of BI on problem drug use based on a broad range of measures including self-reported drug use, urine analysis, admission to drug abuse treatment, and changes in utilization and costs of health care services, arrests, and death with the intent of informing policy and program planning for problem drug use at the local, state, and national levels.Trial registrationClinicalTrials.gov NCT00877331

Alcohol-related problems and primary care in Portugal: the state of the art

Portugal has the highest levels of alcohol consumption in the world and the highest rates of alcohol-related problems. The Portuguese government’s National Plan to Reduce Alcohol Related Problems includes the development of projects that provide training to health professionals in screening and intervention for alcohol use disorders, particularly for professionals who work in primary care. Primary care professionals are the first level of assistance in Portugal’s national health care system and have ongoing contact with people who use primary health centers. High consumption of alcohol is responsible for a number off physical, psychological, and social problems. The high prevalence of excessive alcohol consumption and its high economic, social, and health costs justify the implementation of such projects to address alcohol-related problems. Objectives of the national plan include identifying needs specific to primary care settings; designing a training program tailored to primary care center needs; defining priorities (e.g., providing services and building infrastructure to optimize hazardous and harmful alcohol use management and providing monitoring to ensure adherence to protocols that consider clinical referral procedures and specific indicators); ensuring both undergraduate and postgraduate training; and identifying organizational and political components critical to the successful implementation and dissemination of alcohol screening and brief intervention in primary care. We show preliminary results of the plan and the importance of addressing alcohol-relate problems at the national and international level to facilitate sharing of knowledge and standardizing of evidence-based practice between countries.

Importance of routine alcohol screening and brief intervention in women

We present a case report and review of the literature to demonstrate why screening, brief intervention, and referral to treatment (SBIRT) is important for female primary-care patients. A 25-year-old African American woman presented with right lower-quadrant and flank pain, nausea, fever, and dyspareunia three days after unprotected intercourse. The patient had a past history of sexually transmitted infections. An initial alcohol screening was negative for heavy episodic drinking. Physical exam revealed fever, tachycardia, costovertebral angle tenderness, pelvic tenderness, vaginal discharge, and cervical motion tenderness. Urine analysis showed pyuria and bacteriuria. The patient was admitted with pelvic inflammatory disease (PID) and pyelonephritis. Repeat screening by an SBIRT-trained resident revealed recurrent weekend heavy episodic drinking with unprotected intercourse. The patient was treated with antibiotics and brief intervention. During the intervention, she demonstrated awareness of the link between heavy episodic drinking and PID. She reported high level of importance and readiness to decrease her drinking to prevent recurrences. She improved quickly and was discharged on hospital day three but failed to follow up. This case supports the following findings from the research literature: significant high rates of risky drinking among women, the link between alcohol consumption and high-risk health behaviors, the hesitancy of many women to disclose alcohol misuse, and the importance of linking alcohol misuse identified through brief intervention in primary care with alcohol-related consequences. Routine alcohol screening is indicated for all adult patients, and SBIRT training is an important element of primary-care residency training. Nonjudgmental alcohol screening identified binge drinking in a patient who previously denied it, helped the patient recognize the link between alcohol misuse and hospitalization, and enhanced the patient’s motivation to change. Effective SBIRT in such situations have the potential to prevent recurrent alcohol-related hospitalizations among at-risk drinkers.

Alcohol brief intervention delivered in UK community pharmacies: customers’ experiences

Pharmacy-based alcohol brief intervention (BI) has the potential to identify risky drinkers in the general population, but the opinions of users regarding the service remain relatively unexplored. Alcohol BI was offered to customers by trained pharmacists (n = 29) at 28 London, UK, community pharmacies between February and July 2010. Customers requiring alcohol-use related medication and/or advice were targeted. The Alcohol Use Disorders Identification Test-Consumption (AUDIT-C), a drinking diary, and a readiness to change assessment were used by pharmacists to assess and provide appropriate feedback regarding alcohol use. Customers also received written information, including a UK Department of Health “Units and You” booklet. Following BI, customers were given a confidential service evaluation questionnaire to complete and return to the project team using a prepaid envelope. This invited responses to closed- and open-format questions regarding their initial reason for visiting the pharmacy, why they took up the BI service, and their levels of satisfaction with the service delivery and environment. Of the 134 customers who received a BI, 58% (n = 78) returned the questionnaire. Bringing a prescription for dispensing was the most common reason for the pharmacy visit (55%, n = 43). Wishing to find out about alcohol use and concerns for personal health were the two most reported reasons for taking up the service. Almost one-quarter of customers (n = 18) reported that they liked having increased their alcohol-related awareness, and 18% (n = 14) indicated that they liked the informative written information. The privacy (74%, n = 57), confidentiality (77%, n = 59), and quietness (70%, n = 54) of consulting rooms was rated as good, with 77% (n = 60) of customers reporting they would recommend this service to others. In line with past primary care BI studies, customers were generally positive about the experience of receiving BI in community pharmacies and would recommend it to others.

Modelling the Cost-Effectiveness of Alcohol Screening and Brief Interventions in Primary Care in England

To estimate the cost-effectiveness and resourcing implications of universal alcohol screening and brief intervention (SBI) programmes in primary care in England. This was a health economic model, combining evidence of the effectiveness and health care resource requirements of SBI activities with existing epidemiological modelling of the relationship between alcohol consumption and health harms. Screening patients on registration with a family doctor would steadily capture ~40% of the population over a 10-year programme; screening patients at next primary care consultation would capture 96% of the population over the same period, but with high resourcing needs in the first year. The registration approach, delivered by a practice nurse, provides modest cost savings to the health care system of £120 m over 30 years. Health gains over the same period amount to 32,000 quality-adjusted life years (QALYs). This SBI programme still appears cost-effective (at £6900 per QALY gained) compared with no programme, under pessimistic effectiveness assumptions. Switching to a consultation approach, delivered by a doctor, would incur an incremental net cost of £108 m, with incremental health gains equivalent to 92,000 QALYs, giving an incremental cost-effectiveness ratio of £1175 per QALY gained compared with current practice. A universal programme of alcohol SBI in primary care is estimated to be cost-effective, under all but the most pessimistic assumptions for programme costs and effectiveness. Policymakers should ensure that SBI programmes are routinely evaluated and followed up, given the substantial uncertainty over the effects of many of the implementation details.

Challenges to alcohol and other drug discussions in the general practice consultation

Background. There is a widely held expectation that GPs will routinely use opportunities to provide opportunistic screening and brief intervention for alcohol and other drug (AOD) abuse, a major cause of preventable death and morbidity.Aim. To explore how opportunities arise for AOD discussion in GP consultations and how that advice is delivered.Design. Analysis of video-recorded primary care consultationsSetting. New Zealand General Practice.Methods. Interactional content analysis of AOD consultations between 15 GP’s and 56 patients identified by keyword search from a bank of digital video consultation recordings.Results. AOD-related words were found in almost one-third (56/171) of the GP consultation transcripts (22 female and 34 male patients). The AOD dialogue varied from brief mention to pertinent advice. Tobacco and alcohol discussion featured more often than misuse of anxiolytics, night sedation, analgesics and caffeine, with only one direct enquiry about other (unspecified) recreational drug use. Discussion was associated with interactional delicacy on the part of both doctor and patient, manifested by verbal and non-verbal discomfort, use of closed statements, understatement, wry humour and sudden topic change.Conclusions. Mindful prioritization of competing demands, time pressures, topic delicacy and the acuteness of the presenting complaint can impede use of AOD discussion opportunities. Guidelines and tools for routine screening and brief intervention in primary care do not accommodate this reality. Possible responses to enhance AOD conversations within general practice settings are discussed.

Commentary on ‘The research translation problem: Alcohol screening and brief intervention in primary care – Real world evidence supports theory’

The paper by McCormick et al. (2010) provides real-world examples of best practice for implementing alcohol screening and brief intervention (SBI) in primary care. We commend the authors for that and also wish to highlight the additional challenges involved in implementing SBI in primary care among vulnerable populations, especially problem drug users. To explore the scientific evidence on implementing best practice in SBI for problem alcohol use among problem drug users, we conducted a Medline search with the following keywords: setting (primary care),target behaviour (problem alcohol use), population (problem drug users) and implementation strategies (e.g. guidelines, barriers or enablers). The majority of papers we identified concerned the general adult population and we consider this literature in conjunction with that specific to problem drug users, where relevant.

Implementing alcohol disorders treatment throughout the community

Alcohol is the world's third leading cause of ill-health and premature death. Alcohol has been found to be the most harmful drug, when considering harm to the individual and to others. With a prespecified search strategy we looked for relevant articles concerning screening, brief interventions and referral to treatment of patients with hazardous or harmful alcohol use, with a special focus on the primary healthcare implementation of these effective interventions. The evidence on the efficacy and effectiveness of brief interventions in primary care continues to grow and is confirmed by many recent studies, even in specific populations. The implementation of those effective interventions continues to be difficult, but successful experiences have been reported. The use of brief interventions in other healthcare settings and to address problems other than risky drinking is promising, but the evidence is far from conclusive. Some specific age groups (elderly, women and youth below 16) may deserve specifically tailored interventions. Alcohol is a major public health problem and brief interventions are one of the cost-effective measures that can be taken at a community level. Nevertheless, implementation of those measures is difficult. Further research is needed to identify the best implementation strategies.

12-Month follow-up after brief interventions in primary care for family members affected by the substance misuse problem of a close relative

Following the publication of initial and 3-month data from a prospective cluster randomised comparative trial [Copello, A., Templeton, L., Orford, J., Velleman, R., Patel, A., Moore, L., … , Godfrey, C. (2009). The relative efficacy of two levels of a primary care intervention for family members affected by the addiction problem of a close relative: A randomised trial. Addiction, 104, 49–58.], an opportunistic 12-month follow-up was undertaken. The trial compared two brief interventions for use by primary health care professionals with family members (FMs) affected by the problematic substance use of a close relative. Ninety out of 143 (63%) FMs in the trial were followed up at 12 months. Three validated self-completion questionnaires were re-administered: Symptom Rating Test, Coping Questionnaire and Family Member Impact Scale. At 12 months there were still no significant differences between FMs depending on which of the two brief interventions received. The initial improvements at 12 weeks on all of the measures (symptoms, coping and impact) were maintained, and further improved (FMs reported that their symptoms, their coping behaviours and the impact on them of their relatives’ substance misuse problem all continued to reduce). These improvements were unrelated to a range of demographic variables. FMs also reported a gradual improvement in their relatives’ misusing behaviour over the three time periods. In conclusion, following a brief intervention for affected FMs, either delivered in full via professional intervention or via a self-help manual following a brief introduction from a professional, both groups improve equally; there are significant and positive changes which are both maintained and further increased over a 12-month period, without any further formal delivery of the intervention.

Screening, Brief Intervention, and Referral to Treatment (SBIRT): Toward a Public Health Approach to the Management of Substance Abuse

Summary.Screening, Brief Intervention, and Referral to Treatment (SBIRT) is a comprehensive and integrated approach to the delivery of early intervention and treatment services through universal screening for persons with substance use disorders and those at risk. This paper describes research on the components of SBIRT conducted during the past 25 years, including the development of screening tests, clinical trials of brief interventions and implementation research. Beginning in the 1980s, concerted efforts were made in the US and at the World Health Organization to provide an evidence base for alcohol screening and brief intervention in primary health care settings. With the development of reliable and accurate screening tests for alcohol, more than a hundred clinical trials were conducted to evaluate the efficacy and cost effectiveness of alcohol screening and brief intervention in primary care, emergency departments and trauma centers. With the accumulation of positive evidence, implementation researc...

Alcohol screening and brief intervention in primary care: Absence of evidence for efficacy in people with dependence or very heavy drinking

Although screening and brief intervention (BI) in the primary-care setting reduces unhealthy alcohol use, its efficacy among patients with dependence has not been established. This systematic review sought to determine whether evidence exists for BI efficacy among patients with alcohol dependence identified by screening in primary-care settings. We included randomised controlled trials (RCTs) extracted from eight systematic reviews and electronic database searches published through September 2009. These RCTs compared outcomes among adults with unhealthy alcohol use identified by screening who received BI in a primary-care setting with those who received no intervention. Sixteen RCTs, including 6839 patients, met the inclusion criteria. Of these, 14 excluded some or all persons with very heavy alcohol use or dependence; one in which 35% of 175 patients had dependence found no difference in an alcohol severity score between groups; and one in which 58% of 24 female patients had dependence showed no efficacy. Alcohol screening and BI has efficacy in primary care for patients with unhealthy alcohol use, but there is no evidence for efficacy among those with very heavy use or dependence. As alcohol screening identifies both dependent and non-dependent unhealthy use, the absence of evidence for the efficacy of BI among primary-care patients with screening-identified alcohol dependence raises questions regarding the efficiency of screening and BI, particularly in settings where dependence is common. The finding also highlights the need to develop new approaches to help such patients, particularly if screening and BI are to be disseminated widely.[Saitz R. Alcohol screening and brief intervention in primary care: Absence of evidence for efficacy in people with dependence or very heavy drinking.

The research translation problem: Alcohol screening and brief intervention in primary care – Real world evidence supports theory

Translational research projects based in England, New Zealand and Catalonia are described. In combination they provide real world evidence in support of the evolving discourse on translating the evidence on screening and brief intervention for problem use of alcohol so that it is acceptable and fit for routine practice. Acceptance and uptake was enhanced by encouraging primary health clinicians to use evidence-based screening and brief intervention processes which fit with the context in which they work and which build on the skills they already have and use in practice. Emerging general principles included: tailoring procedures to fit with local circumstances; breaking the process down into clinically acceptable steps and negotiating where there is flexibility. Key issues explored in each case study included how ‘screening’ is best conducted, what is a brief intervention best suited to which provider and which providers should run the process.

Interactive Voice Response Technology Can Deliver Alcohol Screening and Brief Intervention in Primary Care

Alcohol screening and brief intervention (BI) is an effective primary care preventive service, but implementation rates are low. Automating BI using interactive voice response (IVR) may be an efficient way to expand patient access to needed information and advice. To develop IVR-based BI and pilot test it for feasibility and acceptability. Single-group pre-post feasibility study. Primary care patients presenting for an office visit. IVR-BI structured to correspond to the provider BI method recommended by NIAAA: (1) Ask about use; (2) Assess problems; (3) Advise and Assist for change, and (4) Follow up for continued support. Advice was tailored to patient readiness and preferences. Utilization rate, call duration, and patients' subjective reports of usefulness, comfort and honesty with the IVR-BI. Pre-post evaluation of motivation to change and change in alcohol consumption as measured by Timeline Follow Back. Call duration ranged from 3-7 minutes. Subjective reactions were generally positive or neutral. About 40% of subjects indicated IVR-BI had motivated them to change. About half of the patients had discussed drinking with their provider at the visit. These tended to be heavier drinkers with greater concerns about drinking. Patients who reported a provider-delivered BI and called the IVR-BI endorsed greater comfort and honesty with the IVR-BI. On average, a 25% reduction in alcohol use was reported two weeks after the clinic visit. Using IVR technology to deliver BI in a primary care setting is feasible and data suggest potential for efficacy in a larger trial.

Study of Implementation of a Guideline for Brief Alcohol Intervention in Primary Care

Application of research findings to clinical care has been advocated to improve quality of care and patient outcomes. This article discusses a method to evaluate the translation of research findings in support of evidence-based care. An exemplar of a brief intervention in primary care for high-risk drinkers is used.

Screening and brief interventions for hazardous and harmful alcohol use in primary care: a cluster randomised controlled trial protocol.

BackgroundThere have been many randomized controlled trials of screening and brief alcohol intervention in primary care. Most trials have reported positive effects of brief intervention, in terms of reduced alcohol consumption in excessive drinkers. Despite this considerable evidence-base, key questions remain unanswered including: the applicability of the evidence to routine practice; the most efficient strategy for screening patients; and the required intensity of brief intervention in primary care. This pragmatic factorial trial, with cluster randomization of practices, will evaluate the effectiveness and cost-effectiveness of different models of screening to identify hazardous and harmful drinkers in primary care and different intensities of brief intervention to reduce excessive drinking in primary care patients.Methods and designGPs and nurses from 24 practices across the North East (n = 12), London and South East (n = 12) of England will be recruited. Practices will be randomly allocated to one of three intervention conditions: a leaflet-only control group (n = 8); brief structured advice (n = 8); and brief lifestyle counselling (n = 8). To test the relative effectiveness of different screening methods all practices will also be randomised to either a universal or targeted screening approach and to use either a modified single item (M-SASQ) or FAST screening tool. Screening randomisation will incorporate stratification by geographical area and intervention condition. During the intervention stage of the trial, practices in each of the three arms will recruit at least 31 hazardous or harmful drinkers who will receive a short baseline assessment followed by brief intervention. Thus there will be a minimum of 744 patients recruited into the trial.DiscussionThe trial will evaluate the impact of screening and brief alcohol intervention in routine practice; thus its findings will be highly relevant to clinicians working in primary care in the UK. There will be an intention to treat analysis of study outcomes at 6 and 12 months after intervention. Analyses will include patient measures (screening result, weekly alcohol consumption, alcohol-related problems, public service use and quality of life) and implementation measures from practice staff (the acceptability and feasibility of different models of brief intervention.) We will also examine organisational factors associated with successful implementation.Trial registrationCurrent Controlled Trials ISRCTN06145674.

The effectiveness of brief alcohol interventions in primary care settings: A systematic review

Numerous studies have reported that brief interventions delivered in primary care are effective in reducing excessive drinking. However, much of this work has been criticised for being clinically unrepresentative. This review aimed to assess the effectiveness of brief interventions in primary care and determine if outcomes differ between efficacy and effectiveness trials. A pre-specified search strategy was used to search all relevant electronic databases up to 2006. We also hand-searched the reference lists of key articles and reviews. We included randomised controlled trials (RCT) involving patients in primary care who were not seeking alcohol treatment and who received brief intervention. Two authors independently abstracted data and assessed trial quality. Random effects meta-analyses, subgroup and sensitivity analyses and meta-regression were conducted. The primary meta-analysis included 22 RCT and evaluated outcomes in over 5800 patients. At 1 year follow up, patients receiving brief intervention had a significant reduction in alcohol consumption compared with controls [mean difference: -38 g week(-1), 95%CI (confidence interval): -54 to -23], although there was substantial heterogeneity between trials (I(2) = 57%). Subgroup analysis confirmed the benefit of brief intervention in men but not in women. Extended intervention was associated with a non-significantly increased reduction in alcohol consumption compared with brief intervention. There was no significant difference in effect sizes for efficacy and effectiveness trials. Brief interventions can reduce alcohol consumption in men, with benefit at a year after intervention, but they are unproven in women for whom there is insufficient research data. Longer counselling has little additional effect over brief intervention. The lack of differences in outcomes between efficacy and effectiveness trials suggests that the current literature is relevant to routine primary care.

Substance Abuse Screening and Brief Intervention in Primary Care

Substance Abuse Screening and Brief Intervention in Primary Care

Low identification of alcohol use disorders in general practice in England

The prevalence of alcohol use disorders (AUDs) in the United Kingdom is estimated at 25%, and primary care has been identified as the first line of treatment for this population. However, there is a paucity of evidence regarding the current rates of identification of AUDs in primary care. The aim of the present study was to compare the observed rates of AUDs in general practice with expected rates, which are based on general population prevalence rates of AUDs. Epidemiological data on individuals aged 16-64 years with an AUD was obtained from the General Practice Research Database. General population prevalence rates of AUDs were obtained from the Psychiatric Morbidity Survey. Chi(2) tests and identification ratios were used to analyse the data. There was a significant relationship between type of AUD and identification (chi(2)=1466.89, P<0.001), and general practitioners were poorer at identifying harmful/hazardous drinkers when compared with dependent drinkers. No gender differences in the identification of hazardous/harmful drinking were found, but female dependent drinkers were significantly more likely to be identified than males (identification ratio 0.07; 95% confidence interval 0.06-0.07). The identification of AUDs was significantly lower for the 16-24-year age group compared with all other age groups. Despite attempts at targeting hazardous/harmful drinkers for brief interventions in primary care, the present findings suggest that this group are still under-identified. Furthermore, this under-identification is even more apparent in men and in young people who have high general population prevalence rates for AUDs. In conclusion, increasing identification rates could be incorporated into brief intervention strategies in primary care.

Randomized Controlled Trial of Web-Based Alcohol Screening and Brief Intervention in Primary Care

There is compelling evidence supporting screening and brief intervention (SBI) for hazardous drinking, yet it remains underused in primary health care. Electronic (computer or Web-based) SBI (e-SBI) offers the prospects of ease and economy of access. We sought to determine whether e-SBI reduces hazardous drinking. We conducted a randomized controlled trial in a university primary health care service. Participants were 975 students (age range, 17-29 years) screened using the Alcohol Use Disorders Identification Test (AUDIT). Of 599 students who scored in the hazardous or harmful range, 576 (300 of whom were women) consented to the trial and were randomized to receive an information pamphlet (control group), a Web-based motivational intervention (single-dose e-SBI group), or a Web-based motivational intervention with further interventions 1 and 6 months later (multidose e-SBI group). Relative to the control group, the single-dose e-SBI group at 6 months reported a lower frequency of drinking (rate ratio [RR], 0.79; 95% confidence interval [CI], 0.68-0.94), less total consumption (RR, 0.77; 95% CI, 0.63-0.95), and fewer academic problems (RR, 0.76; 95% CI, 0.64-0.91). At 12 months, statistically significant differences in total consumption (RR, 0.77; 95% CI, 0.63-0.95 [equivalent to 3.5 standard drinks per week]) and in academic problems (RR, 0.80; 95% CI, 0.66-0.97) remained, and the AUDIT scores were 2.17 (95% CI, -1.10 to -3.24) points lower. Relative to the control group, the multidose e-SBI group at 6 months reported a lower frequency of drinking (RR, 0.85; 95% CI, 0.73-0.98), less total consumption (RR, 0.79; 95% CI, 0.64-0.97 [equivalent to 3.0 standard drinks per week]), reduced episodic heavy drinking (RR, 0.65; 95% CI, 0.45-0.93), and fewer academic problems (RR, 0.78; 95% CI, 0.65-0.93). At 12 months, statistically significant differences in academic problems remained (RR, 0.75; 95% CI, 0.62-0.90), while the AUDIT scores were 2.02 (95% CI, -0.97 to -3.10) points lower. Single-dose e-SBI reduces hazardous drinking, and the effect lasts 12 months. Additional sessions seem not to enhance the effect. Trial Registration www.anzctr.org.au Identifier:ACTRN012607000103460.

Screening, Brief Intervention, and Referral to Treatment (SBIRT)

SUMMARY Screening, Brief Intervention, and Referral to Treatment (SBIRT) is a comprehensive and integrated approach to the delivery of early intervention and treatment services through universal screening for persons with substance use disorders and those at risk. This paper describes research on the components of SBIRT conducted during the past 25 years, including the development of screening tests, clinical trials of brief interventions and implementation research. Beginning in the 1980s, concerted efforts were made in the US and at the World Health Organization to provide an evidence base for alcohol screening and brief intervention in primary health care settings. With the development of reliable and accurate screening tests for alcohol, more than a hundred clinical trials were conducted to evaluate the efficacy and cost effectiveness of alcohol screening and brief intervention in primary care, emergency departments and trauma centers. With the accumulation of positive evidence, implementation research on alcohol SBI was begun in the 1990s, followed by trials of similar methods for other substances (e.g., illicit drugs, tobacco, prescription drugs) and by national demonstration programs in the US and other countries. The results of these efforts demonstrate the cumulative benefit of translational research on health care delivery systems and substance abuse policy. That SBIRT yields short-term improvements in individuals' health is irrefutable; long-term effects on population health have not yet been demonstrated, but simulation models suggest that the benefits could be substantial.