Screening for Prediabetes and Type 2 Diabetes: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force.

Importance: Type 2 diabetes is common and is a leading cause of morbidity and disability. Objective: To review the evidence on screening for prediabetes and diabetes to inform the US Preventive Services Task Force (USPSTF). Data Sources: PubMed/MEDLINE, Cochrane Library, and trial registries through September 2019; references; and experts; literature surveillance through May 21, 2021. Study Selection: English-language controlled studies evaluating screening or interventions for prediabetes or diabetes that was screen detected or recently diagnosed. Data Extraction and Synthesis: Dual review of abstracts, full-text articles, and study quality; qualitative synthesis of findings; meta-analyses conducted when at least 3 similar studies were available. Main Outcomes and Measures: Mortality, cardiovascular morbidity, diabetes-related morbidity, development of diabetes, quality of life, and harms. Results: The review included 89 publications (N = 68 882). Two randomized clinical trials (RCTs) (25 120 participants) found no significant difference between screening and control groups for all-cause or cause-specific mortality at 10 years. For harms (eg, anxiety or worry), the trials reported no significant differences between screening and control groups. For recently diagnosed (not screen-detected) diabetes, 5 RCTs (5138 participants) were included. In the UK Prospective Diabetes Study, health outcomes were improved with intensive glucose control with sulfonylureas or insulin. For example, for all-cause mortality the relative risk (RR) was 0.87 (95% CI, 0.79 to 0.96) over 20 years (10-year posttrial assessment). For overweight persons, intensive glucose control with metformin improved health outcomes at the 10-year follow-up (eg, all-cause mortality: RR, 0.64 [95% CI, 0.45 to 0.91]), and benefits were maintained longer term. Lifestyle interventions (most involving >360 minutes) for obese or overweight persons with prediabetes were associated with reductions in the incidence of diabetes (23 RCTs; pooled RR, 0.78 [95% CI, 0.69 to 0.88]). Lifestyle interventions were also associated with improved intermediate outcomes, such as reduced weight, body mass index, systolic blood pressure, and diastolic blood pressure (pooled weighted mean difference, -1.7 mm Hg [95% CI, -2.6 to -0.8] and -1.2 mm Hg [95% CI, -2.0 to -0.4], respectively). Metformin was associated with a significant reduction in diabetes incidence (pooled RR, 0.73 [95% CI, 0.64 to 0.83]) and reduction in weight and body mass index. Conclusions and Relevance: Trials of screening for diabetes found no significant mortality benefit but had insufficient data to assess other health outcomes; evidence on harms of screening was limited. For persons with recently diagnosed (not screen-detected) diabetes, interventions improved health outcomes; for obese or overweight persons with prediabetes, interventions were associated with reduced incidence of diabetes and improvement in other intermediate outcomes.

Screening for Cardiovascular Disease Risk With Resting or Exercise Electrocardiography: Evidence Report and Systematic Review for the US Preventive Services Task Force.

Importance: Cardiovascular disease (CVD) is the leading cause of death in the United States. Objective: To review the evidence on screening asymptomatic adults for CVD risk using electrocardiography (ECG) to inform the US Preventive Services Task Force. Data Sources: MEDLINE, Cochrane Library, and trial registries through May 2017; references; experts; literature surveillance through April 4, 2018. Study Selection: English-language randomized clinical trials (RCTs); prospective cohort studies reporting reclassification, calibration, or discrimination that compared risk assessment using ECG plus traditional risk factors vs traditional risk factors alone. For harms, additional study designs were eligible. Studies of persons with symptoms or a CVD diagnosis were excluded. Data Extraction and Synthesis: Dual review of abstracts, full-text articles, and study quality; qualitative synthesis of findings. Main Outcomes and Measures: Mortality, cardiovascular events, reclassification, calibration, discrimination, and harms. Results: Sixteen studies were included (N = 77 140). Two RCTs (n = 1151) found no significant improvement for screening with exercise ECG (vs no screening) in adults aged 50 to 75 years with diabetes for the primary cardiovascular composite outcomes (hazard ratios, 1.00 [95% CI, 0.59-1.71] and 0.85 [95% CI, 0.39-1.84] for each study). No RCTs evaluated screening with resting ECG. Evidence from 5 cohort studies (n = 9582) showed that adding exercise ECG to traditional risk factors such as age, sex, current smoking, diabetes, total cholesterol level, and high-density lipoprotein cholesterol level produced small improvements in discrimination (absolute improvements in area under the curve [AUC] or C statistics, 0.02-0.03, reported by 3 studies); whether calibration or appropriate risk classification improves is uncertain. Evidence from 9 cohort studies (n = 66 407) showed that adding resting ECG to traditional risk factors produced small improvements in discrimination (absolute improvement in AUC or C statistics, 0.001-0.05) and appropriate risk classification for prediction of multiple cardiovascular outcomes, although evidence was limited by imprecision, quality, considerable heterogeneity, and inconsistent use of risk thresholds used for clinical decision making. Total net reclassification improvements ranged from 3.6% (2.7% event; 0.6% nonevent) to 30% (17% event; 19% nonevent) for studies using the Framingham Risk Score or Pooled Cohort Equations base models. Evidence on potential harms (eg, from subsequent angiography or revascularization) in asymptomatic persons was limited. Conclusions and Relevance: RCTs of screening with exercise ECG found no improvement in health outcomes, despite focusing on higher-risk populations with diabetes. The addition of resting ECG to traditional risk factors accurately reclassified persons, but evidence for this finding had many limitations. The frequency of harms from screening is uncertain.

The psychological harms of screening: the evidence we have versus the evidence we need.

BACKGROUND: Systematic reviews for the US Preventive Services Task Force have found less high-quality evidence on psychological than physical harms of screening. To understand the extent of evidence on psychological harms, we developed an evidence map that quantifies the distribution of evidence on psychological harms for five adult screening services. We also note gaps in the literature and make recommendations for future research. METHODS: We systematically searched PubMed, PsycInfo, and CINAHL from 2002 to 2012 for studies of any research design that assessed the burden or frequency of psychological harm associated with screening for: prostate and lung cancers, osteoporosis, abdominal aortic aneurysm (AAA) and carotid artery stenosis (CAS). We also searched for studies that estimated rates of overdiagnosis (a marker for unnecessary labeling). We included studies published in English and used dual independent review to determine study inclusion and to abstract information on design, types of measures, and outcomes assessed. RESULTS: Sixty-eight studies assessing psychological harms met our criteria; 62 % concerned prostate cancer and 16 % concerned lung cancer. Evidence was scant for the other three screening services. Overall, only about one-third of the studies used both longitudinal designs and condition-specific measures (ranging from 0 % for AAA and CAS to 78 % for lung cancer), which can provide the best evidence on harms. An additional 20 studies that met our criteria estimated rates of overdiagnosis in lung or prostate cancer. No studies estimated overdiagnosis for the non-cancer screening services. DISCUSSION: Evidence on psychological harms varied markedly across screening services in number and potential usefulness. We found important evidence gaps for all five screening services. The evidence that we have on psychological harms is inadequate in number of studies and in research design and measures. Future research should focus more clearly on the evidence that we need for decision making about screening.

Barriers to recruiting primary care practices for implementation research during COVID-19: A qualitative study of practice coaches from the Stop Unhealthy (STUN) Alcohol Use Now trial.

Background: The COVID-19 pandemic has brought widespread change to health care practice and research. With heightened stress in the general population, increased unhealthy alcohol use, and added pressures on primary care practices, comes the need to better understand how we can continue practice-based research and address public health priorities amid the ongoing pandemic. The current study considers barriers and facilitators to conducting such research, especially during the COVID-19 pandemic, within the context of recruiting practices for the STop UNhealthy (STUN) Alcohol Use Now trial. The STUN trial uses practice facilitation to implement screening and interventions for unhealthy alcohol use in primary care practices across the state of North Carolina. Methods: Semistructured interviews were conducted with a purposive sample of 15 practice coaches to discuss their recruitment experiences before and after recruitment was paused due to the pandemic. An inductive thematic analysis was used to identify themes and subthemes. Results: Pandemic-related barriers, including challenges in staffing, finances, and new COVID-19-related workflows, were most prominent. Competing priorities, such as quality improvement measures, North Carolina's implementation of Medicaid managed care, and organizational structures hampered recruitment efforts. Coaches also described barriers specific to the project and to the topic of alcohol. Several facilitators were identified, including the rising importance of behavioral health due to the pandemic, as well as existing relationships between practice coaches and practices. Conclusions: Difficulty managing competing priorities and obstacles within existing practice infrastructure inhibit the ability to participate in practice-based research and implementation of evidence-based practices. Lessons learned from this trial may inform strategies to recruit practices into research and to gain buy-in from practices in adopting evidence-based practices more generally. Plain Language Summary: What is known: Unhealthy alcohol use is a significant public health issue, which has been exacerbated during the COVID-19 pandemic. Screening and brief intervention for unhealthy alcohol use is an evidence-based practice shown to help reduce drinking-related behaviors, yet it remains rare in practice. What this study adds: Using a qualitative approach, we identify barriers and facilitators to recruiting primary care practices into a funded trial that uses practice facilitation to address unhealthy alcohol use. We identify general insights as well as those specific to the COVID-19 pandemic. Barriers are primarily related to competing priorities, incentives, and lack of infrastructure. Facilitators are related to framing of the project and the anticipated level and type of resources needed to address unhealthy alcohol use especially as the pandemic wanes. Implications: Our findings provide information on barriers and facilitators to recruiting primary care practices for behavioral health projects and to implementing these activities. Using our findings, we provide a discussion of suggestions for conducting these types of projects in the future which may be of interest to researchers, practice managers, and providers.

The STUN (STop UNhealthy) Alcohol Use Now trial: study protocol for an adaptive randomized trial on dissemination and implementation of screening and management of unhealthy alcohol use in primary care.

BACKGROUND: Unhealthy alcohol use is a leading cause of preventable deaths in the USA and is associated with many societal and health problems. Less than a third of people who visit primary care providers in the USA are asked about or ever discuss alcohol use with a health professional. METHODS/DESIGN: This study is an adaptive, randomized, controlled trial to evaluate the effect of primary care practice facilitation and telehealth services on evidence-based screening, counseling, and pharmacotherapy for unhealthy alcohol use in small-to-medium-sized primary care practices. Study participants will include primary care practices in North Carolina with 10 or fewer providers. All enrolled practices will receive a practice facilitation intervention that includes quality improvement (QI) coaching, electronic health record (EHR) support, training, and expert consultation. After 6 months, practices in the lower 50th percentile (based on performance) will be randomized to continued practice facilitation or provision of telehealth services plus ongoing facilitation for the next 6 months. Practices in the upper 50th percentile after the initial 6 months of intervention will continue to receive practice facilitation alone. The main outcome measures include the number (and %) of patients in the target population who are screened for unhealthy alcohol use, screen positive, and receive brief counseling. Additional measures include the number (and %) of patients who receive pharmacotherapy for AUD or are referred for AUD services. Sample size calculations determined that 35 practices are needed to detect a 10% increase in the main outcome (percent screened for unhealthy alcohol use) over 6 months. DISCUSSION: A successful intervention would significantly reduce morbidity among adults from unhealthy alcohol use by increasing counseling and other treatment opportunities. The study will produce important evidence about the effect of practice facilitation on uptake of evidence-based screening, counseling, and pharmacotherapy for unhealthy alcohol use when delivered on a large scale to small and medium-sized practices. It will also generate scientific knowledge about whether embedded telehealth services can improve the use of evidence-based screening and interventions for practices with slower uptake. The results of this rigorously conducted evaluation are expected to have a positive impact by accelerating the dissemination and implementation of evidence related to unhealthy alcohol use into primary care practices. TRIAL REGISTRATION: ClinicalTrials.gov NCT04317989 . Registered on March 23, 2020.

Implementing Evidence-Based Screening and Counseling for Unhealthy Alcohol Use with Epic-Based Electronic Health Record Tools.

BACKGROUND: Multiple national organizations recommend screening and counseling adults for unhealthy alcohol use. METHODS: An evidence-based approach to screening and counseling using Epic electronic health record (EHR) tools was implemented in a general medicine clinic. A dissemination package with actionable steps for clinics and systems wishing to implement similar processes was then produced. To evaluate the initial implementation and quality improvement project, run charts were created to track patients screened, patients counseled, and fidelity to protocols, and members of the original project team were interviewed to assess facilitators and barriers. The draft dissemination package was revised after feedback from health system representatives (key informants). RESULTS: More than 9,000 patients (73.9% of those eligible) were screened in 20 months. Sixty-four percent of patients with positive initial screens had documented screening-related assessment; 39.7% (141/355) were offered counseling when indicated. Initial project team members identified EHR tools, clinic leadership, quality improvement culture, a multidisciplinary team, and training for providers and nurses as facilitators; and competing demands, patient population size, and nursing staff/resident turnover as barriers. Six key informants evaluated the dissemination package. Most rated 10 of the 12 sections as very useful; all rated components specific to implementing alcohol screening and counseling as very useful. Ratings for general guidance on implementing evidence-based services in primary care were more mixed. CONCLUSION: Evidence-based screening and counseling for unhealthy alcohol use can be implemented with EHR tools. A dissemination guide was viewed favorably by key informants and can serve as a guide for other clinics and systems.

A Decision Aid to Promote Appropriate Colorectal Cancer Screening among Older Adults: A Randomized Controlled Trial.

BACKGROUND: Concerns have been raised about both over- and underutilization of colorectal cancer (CRC) screening in older patients and the need to align screening behavior with likelihood of net benefit. OBJECTIVE: The purpose of this study was to test a novel use of a patient decision aid (PtDA) to promote appropriate CRC screening in older adults. METHODS: A total of 424 patients ages 70 to 84 y who were not up to date with CRC screening participated in a double-blinded randomized controlled trial of a PtDA targeted to older adults making decisions about whether to undergo CRC screening from March 2012 to February 2015. INTERVENTION: Patients were randomized to a targeted PtDA or an attention control. The PtDA was designed to facilitate individualized decision making-helping patients understand the potential risks, benefits, and uncertainties of CRC screening given advanced age, health state, preferences, and values. OUTCOMES: Two composite outcomes, appropriate CRC screening behavior 6 mo after the index visit and appropriate screening intent immediately after the visit, were defined as completed screening or intent for patients in good health, discussion about screening with their provider for patients in intermediate health, and no screening or intent for patients in poor health. Health state was determined by age and Charlson Comorbidity Index. RESULTS: Four hundred twelve (97%) and 421 (99%) patients were analyzed for the primary and secondary outcomes, respectively. Appropriate screening behavior at 6 mo was higher in the intervention group (55% v. 45%, P = 0.023) as was appropriate screening intent following the provider visit (61% v. 47%, P = 0.003). LIMITATIONS: The study took place in a single geographic region. The appropriate CRC screening classification system used in this study has not been formally validated. CONCLUSIONS: A PtDA for older adults promoted appropriate CRC screening behavior and intent. TRIAL REGISTRATION: Clinicaltrials.gov, registration number NCT01575990. https://clinicaltrials.gov/ct2/show/NCT01575990?term=epic-d&rank=1.

Exploring factors that might influence primary-care provider discussion of and recommendation for prostate and colon cancer screening.

BACKGROUND: Primary-care providers may contribute to the use of low-value cancer screening. OBJECTIVE: We sought to examine circumstances under which primary-care providers would discuss and recommend two types of cancer screening services across a spectrum of net benefit and other factors known to influence screening. PATIENTS AND METHODS: This was a cross sectional survey of 126 primary-care providers in 24 primary-care clinics in the US. Participants completed surveys with two hypothetical screening scenarios for prostate or colorectal cancer (CRC). Patients in the scenarios varied by age and screening-request status. For each scenario, providers indicated whether they would discuss and recommend screening. Providers also reported on their screening attitudes and the influence of other factors known to affect screening (short patient visits, worry about lawsuits, clinical reminders/performance measures, and screening guidelines). We examined associations between providers' attitudes and their screening recommendations for hypothetical 90-year-olds (the lowest-value screening). RESULTS: Providers reported they would discuss cancer screening more often than they would recommend it (P<0.001). More providers would discuss and recommend screening for CRC than prostate cancer (P<0.001), for younger than older patients (P<0.001), and when the patient requested it than when not (P<0.001). For a 90-year-old patient, every point increase in cancer-specific screening attitude increased the likelihood of a screening recommendation (30% for prostate cancer and 30% for CRC). DISCUSSION: While most providers' reported practice patterns aligned with net benefit, some providers would discuss and recommend low-value cancer screening, particularly when faced with a patient request. CONCLUSION: More work appears to be needed to help providers to discuss and recommend screening that aligns with value.

Do psychological harms result from being labelled with an unexpected diagnosis of abdominal aortic aneurysm or prostate cancer through screening? A systematic review.

OBJECTIVE: A potential psychological harm of screening is unexpected diagnosis-labelling. We need to know the frequency and severity of this harm to make informed decisions about screening. We asked whether current evidence allows an estimate of any psychological harm of labelling. As case studies, we used two conditions for which screening is common: prostate cancer (PCa) and abdominal aortic aneurysm (AAA). DESIGN: Systematic review with narrative synthesis. DATA SOURCES AND ELIGIBILITY CRITERIA: We searched the English language literature in PubMed, PsychINFO and Cumulative Index of Nursing and Allied Health Literature (CINAHL) for research of any design published between 1 January 2002 and 23 January 2017 that provided valid data about the psychological state of people recently diagnosed with early stage PCa or AAA. Two authors independently used explicit criteria to review and critically appraise all studies for bias, applicability and the extent to which it provided evidence about the frequency and severity of harm from labelling. RESULTS: 35 quantitative studies (30 of PCa and 5 of AAA) met our criteria, 17 (48.6%) of which showed possible or definite psychological harm from labelling. None of these studies, however, had either appropriate measures or relevant comparisons to estimate the frequency and severity of psychological harm. Four PCa and three AAA qualitative studies all showed clear evidence of at least moderate psychological harm from labelling. Seven population-based studies found increased suicide in patients recently diagnosed with PCa. CONCLUSIONS: Although qualitative and population-based studies show that at least moderate psychological harm due to screening for PCa and AAA does occur, the current quantitative evidence is insufficient to allow a more precise estimation of frequency and severity. More sensitive measures and improved research designs are needed to fully characterise this harm. In the meantime, clinicians and recommendation panels should be aware of the occurrence of this harm.

A Comparative Effectiveness Trial of Alternate Formats for Presenting Benefits and Harms Information for Low-Value Screening Services: A Randomized Clinical Trial.

IMPORTANCE: Healthcare overuse, the delivery of low-value services, is increasingly recognized as a critical problem. However, little is known about the comparative effectiveness of alternate formats for presenting benefits and harms information to patients as a strategy to reduce overuse. OBJECTIVE: To examine the effect of different benefits and harms presentations on patients' intentions to accept low-value or potentially low-value screening services (prostate cancer screening in men ages 50-69 years; osteoporosis screening in low-risk women ages 50-64 years; or colorectal cancer screening in men and women ages 76-85 years). DESIGN, SETTING, AND PARTICIPANTS: Randomized clinical trial of 775 individuals eligible to receive information about any 1 of the 3 screening services and scheduled for a visit with their clinician. Participants were randomized to 1 of 4 intervention arms that differed in terms of presentation format: words, numbers, numbers plus narrative, and numbers plus framed presentation. The trial was conducted from September 2012 to June 2014 at 2 family medicine and 2 internal medicine practices affiliated with the Duke Primary Care Research Consortium. The data were analyzed between May and September of 2015. INTERVENTIONS: One-page evidence-based decision support sheets on each of the 3 screening services, with benefits and harms information presented in 1 of 4 formats: words, numbers, numbers plus narratives, or numbers plus a framed presentation. MAIN OUTCOMES AND MEASURES: The primary outcome was change in intention to accept screening (on a response scale from 1 to 5). Our secondary outcomes included general and disease-specific knowledge, perceived risk and consequences of disease, screening attitudes, perceived net benefit of screening, values clarity, and self-efficacy for screening. RESULTS: We enrolled and randomly allocated 775 individuals, aged 50 to 85 years, to 1 of 4 intervention arms: 195 to words, 192 to numbers, 196 to narrative, and 192 to framed formats. Intentions to accept screening were high before the intervention and change in intentions did not differ across intervention arms (words, -0.07; numbers, -0.05; numbers plus narrative, -0.12; numbers plus framed presentation, -0.02; P = .57 for all comparisons). Change in other outcomes also showed no difference across intervention arms. Results were similar when stratified by screening service. CONCLUSIONS AND RELEVANCE: Single, brief, written decision support interventions, such as the ones in this study, are unlikely to be sufficient to change intentions for screening. Alternate and additional interventions are needed to reduce overused screening services. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01694784.

The harms of screening: a proposed taxonomy and application to lung cancer screening.

IMPORTANCE: Making rational decisions about screening requires information about its harms, but high-quality evidence is often either not available or not used. One reason may be that we lack a coherent framework, a taxonomy, for conceptualizing and studying these harms. OBJECTIVE: To create a taxonomy, we categorized harms from several sources: systematic reviews of screening, other published literature, and informal discussions with clinicians and patients. We used this information to develop an initial taxonomy and vetted it with local and national experts, making revisions as needed. RESULTS: We propose a taxonomy with 4 domains of harm from screening: physical effects, psychological effects, financial strain, and opportunity costs. Harms can occur at any step of the screening cascade. We provide definitions for each harm domain and illustrate the taxonomy using the example of screening for lung cancer. CONCLUSIONS AND RELEVANCE: The taxonomy provides a systematic way to conceptualize harms as experienced by patients. As shown in the lung cancer screening example, the taxonomy also makes clear where (which domains of harms and which parts of the screening cascade) we have useful information and where there are gaps in our knowledge. The taxonomy needs further testing and validation across a broad range of screening programs. We hope that further development of this taxonomy can improve our thinking about the harms of screening, thus informing our research, policy making, and decision making with patients about the wisdom of screening.

Socioeconomic disparities in adverse birth outcomes: a systematic review.

CONTEXT: Adverse birth outcomes, such as preterm birth and low birth weight, have serious health consequences across the life course. Socioeconomic disparities in birth outcomes have not been the subject of a recent systematic review. The aim of this study was to systematically review the literature on the association of socioeconomic disadvantage with adverse birth outcomes, with specific attention to the strength and consistency of effects across socioeconomic measures, birth outcomes, and populations. EVIDENCE ACQUISITION: Relevant articles published from 1999 to 2007 were obtained through electronic database searches and manual searches of reference lists. English-language studies from industrialized countries were included if (1) study objectives included examination of a socioeconomic disparity in a birth outcome and (2) results were presented on the association between a socioeconomic predictor and a birth outcome related to birth weight, gestational age, or intrauterine growth. Two reviewers extracted data and independently rated study quality; data were analyzed in 2008-2009. EVIDENCE SYNTHESIS: Ninety-three of 106 studies reported a significant association, overall or within a population subgroup, between a socioeconomic measure and a birth outcome. Socioeconomic disadvantage was consistently associated with increased risk across socioeconomic measures, birth outcomes, and countries; many studies observed racial/ethnic differences in the effect of socioeconomic measures. CONCLUSIONS: Socioeconomic differences in birth outcomes remain pervasive, with substantial variation by racial or ethnic subgroup, and are associated with disadvantage measured at multiple levels (individual/family, neighborhood) and time points (childhood, adulthood), and with adverse health behaviors that are themselves socially patterned. Future reviews should focus on identifying interventions to successfully reduce socioeconomic disparities in birth outcomes.

Health disparities beginning in childhood: a life-course perspective.

In this article we argue for the utility of the life-course perspective as a tool for understanding and addressing health disparities across socioeconomic and racial or ethnic groups, particularly disparities that originate in childhood. Key concepts and terms used in life-course research are briefly defined; as resources, examples of existing literature and the outcomes covered are provided along with examples of longitudinal databases that have often been used for life-course research. The life-course perspective focuses on understanding how early-life experiences can shape health across an entire lifetime and potentially across generations; it systematically directs attention to the role of context, including social and physical context along with biological factors, over time. This approach is particularly relevant to understanding and addressing health disparities, because social and physical contextual factors underlie socioeconomic and racial/ethnic disparities in health. A major focus of life-course epidemiology has been to understand how early-life experiences (particularly experiences related to economic adversity and the social disadvantages that often accompany it) shape adult health, particularly adult chronic disease and its risk factors and consequences. The strong life-course influences on adult health could provide a powerful rationale for policies at all levels--federal, state, and local--to give more priority to investment in improving the living conditions of children as a strategy for improving health and reducing health disparities across the entire life course.

Phosphoglucose isomerase genotype affects running speed and heat shock protein expression after exposure to extreme temperatures in a montane willow beetle.

Eastern Sierra Nevada populations of the willow beetle Chrysomela aeneicollis commonly experience stressfully high and low environmental temperatures that may influence survival and reproduction. Allele frequencies at the enzyme locus phosphoglucose isomerase (PGI) vary across a climatic latitudinal gradient in these populations, with PGI allele 1 being most common in cooler regions and PGI allele 4 in warmer ones. PGI genotypes differ in heat and cold tolerance and in expression of a 70 kDa heat shock protein. Here we examine genetic, behavioral and environmental factors affecting a performance character, running speed, for willow beetles, and assess effects of consecutive cold and heat exposure on running speed and expression of Hsp70 in the laboratory. In nature, running speed depends on air temperature and is higher for males than females. Mating beetles ran faster than single beetles, and differences among PGI genotypes in male running speed depended on the presence of females. In the laboratory, exposure to cold reduced subsequent running speed, but the amount of this reduction depended on PGI genotype and previous thermal history. Effects of exposure to heat also depended on life history stage and PGI genotype. Adults possessing allele 1 ran fastest after a single exposure to stressful temperature, whereas those possessing allele 4 ran faster after repeated exposure. Larvae possessing allele 4 ran fastest after a single stressful exposure, but running speed generally declined after a second exposure to stressful temperature. The ranking of PGI genotypes after the second exposure depended on whether a larva had been exposed to cold or heat. Effects of temperature on Hsp70 expression also varied among PGI genotypes and depended on type of exposure, especially for adults (single heat exposure, two cold exposures: PGI 1-1>1-4>4-4; other multiple extreme exposures: 4-4>1-4>1-1). There was no consistent association between alleles at other polymorphic enzyme loci and running speed or Hsp70 expression. These data suggest that variation at PGI is associated with considerable plasticity in running speed. Differences in Hsp70 expression among PGI genotypes suggest that the heat-shock response may buffer differences in thermal tolerance and performance among genotypes and help maintain the PGI polymorphism in a thermally variable environment.