- Minneapolis, Minnesota, United States
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BackgroundPrevious studies suggest that many physicians and medical trainees have trouble calculating the probability that a patient has a condition, also known as the predictive value.ActivityTwo questions from the medical literature... more
BackgroundPrevious studies suggest that many physicians and medical trainees have trouble calculating the probability that a patient has a condition, also known as the predictive value.ActivityTwo questions from the medical literature were administered to medical students, residents (post-medical school), fellows (post-residency), and faculty physicians.ResultsOnly 6% answered both questions correctly. Most commonly, the participants grossly overestimated the probability of disease.DiscussionPhysicians still struggle with the ability to calculate predictive values, a skill that affects all branches of medicine and will become more consequential as new tests are administered to patients at low risk for disease.
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AARON L. BAGGISH, BRIAN J. COLE, L. BRUCE GLADDEN, MARK R. HUTCHINSON, MARGOT PUTUKIAN, STEVEN D. STOVITZ, and THOMAS M. BEST Cardiovascular Performance Program, Cardiology Division, Massachusetts General Hospital, Boston, MA; Departments... more
AARON L. BAGGISH, BRIAN J. COLE, L. BRUCE GLADDEN, MARK R. HUTCHINSON, MARGOT PUTUKIAN, STEVEN D. STOVITZ, and THOMAS M. BEST Cardiovascular Performance Program, Cardiology Division, Massachusetts General Hospital, Boston, MA; Departments of Orthopedics and Surgery, Rush University Medical Center, Chicago, IL; School of Kinesiology, Auburn University, Auburn, AL; Sports Medicine Services, Department of Orthopedics, University of Illinois at Chicago, Chicago, IL; University Health Services, Athletic Medicine, Princeton University, Princeton, NJ; University of Minnesota, Department of Family Medicine and Community Health, Minneapolis, MN; and Miami Sports Medicine Institute, Departments of Orthopedics, Biomedical Engineering, Kinesiology, University of Miami, Coral Gables, FL
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A basic principle in epidemiology is that an injury rate should only include time when a person is ‘at risk’ for the outcome. However, when calculating injury rates in sports medicine, many investigators use a method known as ‘athlete-... more
A basic principle in epidemiology is that an injury rate should only include time when a person is ‘at risk’ for the outcome. However, when calculating injury rates in sports medicine, many investigators use a method known as ‘athlete- exposures’ (AE) which was originally proposed by the National Collegiate Athletic Association (NCAA) surveillance programme.1 The AE method overestimates game injury rates when compared with using individual player time as the AE method attributes a full exposure to those who do not play a full game.2 Another method of capturing player exposure to injury is called the athletes-at-risk (AAR) method.2 The AAR method follows proper epidemiological principles, provides results very similar to the individual player time method in most contexts, and is easier to calculate. While the AE method will most often underestimate injury rates, the amount of underestimation depends on the sport and context. Our previous publication2 discusses these concepts …
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Evidence-based medicine (EBM) calls on clinicians to incorporate the ‘best available evidence’ into clinical decision-making. For decisions regarding treatment, the best evidence is that which determines the causal effect of treatments on... more
Evidence-based medicine (EBM) calls on clinicians to incorporate the ‘best available evidence’ into clinical decision-making. For decisions regarding treatment, the best evidence is that which determines the causal effect of treatments on the clinical outcomes of interest. Unfortunately, research often provides evidence where associations are not due to cause-and-effect, but rather due to non-causal reasons. These non-causal associations may provide valid evidence for diagnosis or prognosis, but biased evidence for treatment effects. Causal inference aims to determine when we can infer that associations are or are not due to causal effects. Since recommending treatments that do not have beneficial causal effects will not improve health, causal inference can advance the practice of EBM. The purpose of this article is to familiarise clinicians with some of the concepts and terminology that are being used in the field of causal inference, including graphical diagrams known as ‘causal directed acyclic graphs’. In order to demonstrate some of the links between causal inference methods and clinical treatment decision-making, we use a clinical vignette of assessing treatments to lower cardiovascular risk. As the field of causal inference advances, clinicians familiar with the methods and terminology will be able to improve their adherence to the principles of EBM by distinguishing causal effects of treatment from results due to non-causal associations that may be a source of bias.
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OBJECTIVES To illustrate why the research question determines whether and how sport medicine investigators should adjust for workload when interested in interventions or causal risk factors for injury. DESIGN Theoretical... more
OBJECTIVES To illustrate why the research question determines whether and how sport medicine investigators should adjust for workload when interested in interventions or causal risk factors for injury. DESIGN Theoretical conceptualization. METHODS We use current concepts of causal inference to demonstrate the advantages and disadvantages of adjusting for workload through different analytic approaches when evaluating causal effects on injury risk. RESULTS When a risk factor of interest changes workload, including workload in the regression will cause bias. When workload represents time-at-risk (e.g. games played, minutes run), including workload as an offset in Poisson regression provides a comparison of injury rates (injuries per unit time). This is equivalent to including log(workload) as an independent variable with the coefficient fixed to 1. If workload is included as an independent variable instead of an offset, using log(workload) rather than workload is more consistent with theory. This practice is similar to the principles of allometric scaling. When workload represents a combination of both time-at-risk and intensity, such as with session ratings of perceived exertion, the optimal analytical strategy may require modeling time-at-risk and intensity separately rather than as one factor. CONCLUSIONS Whether to account for recent workload or not, and how to account for recent workload, depends on the research question and the causal assumptions, both of which should be explicitly stated.
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BackgroundFrustrated with the onslaught of articles reporting fascination with results that appear paradoxical but are merely due to selection bias, we studied the apparent effect of obesity on diabetes risk in youth who had a test for... more
BackgroundFrustrated with the onslaught of articles reporting fascination with results that appear paradoxical but are merely due to selection bias, we studied the apparent effect of obesity on diabetes risk in youth who had a test for diabetes. We hypothesised that obese subjects would have lower rates of diabetes than non-obese subjects due to selection bias, and consequently, obesity would appear to lower the risk of diabetes.MethodsRetrospective cohort study of children (4–9 years), pre-teens (10–12 years) and teenagers (13–19 years). Participation was restricted to those who had a test of haemoglobin A1C along with measured height and weight. Body mass index percentile via the Centers for Disease Control and Prevention age and sex standards was calculated and categorised. The main outcome was A1C%, subsequently categorised at the level for diagnosis of diabetes mellitus (≥6.5%).ResultsThe sample consisted of 134 (2%) underweight, 1718 (30%) healthy weight, 660 (12%) overweight and 3190 (56%) obese individuals. 16% (n=936) had an A1C≥6.5%. Overall, healthy weight children had 8.2 times the risk of A1C≥6.5% (95% CI 5.3 to 12.7) compared with those in the obese category. The relative risk was 13 in pre-teens (95% CI 8.5 to 20.0) and 3.9 in teenagers (95% CI 3.3 to 4.7).ConclusionsHealthy weight was associated with a 4–13 times higher relative risk of diabetes mellitus compared with being obese. While apparently shocking, the study’s fatal flaw (selection bias) explains the ‘paradoxical’ finding. Ignoring selection bias can delay advances in medical science.
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Most SARS-CoV-2 antibody assays cannot distinguish between antibodies which developed after natural infection from those which developed after vaccination. We assessed the accuracy of a nucleocapsid-containing assay in identifying natural... more
Most SARS-CoV-2 antibody assays cannot distinguish between antibodies which developed after natural infection from those which developed after vaccination. We assessed the accuracy of a nucleocapsid-containing assay in identifying natural infection among vaccinated individuals. A longitudinal cohort comprised of healthcare workers in the Minneapolis/St. Paul area was enrolled. Two rounds of seroprevalence studies separated by one month were conducted from 11/2020–1/2021 among n=81 participants. Capillary blood from rounds 1 and 2 was tested for IgG antibodies against spike proteins via ELISA (spike-only assay). During round 2, IgGs reactive to SARS-CoV-2 nucleocapsid protein (nucleocapsid-containing assay) were assessed. Vaccination status at round 2 was determined via self-report. Area under the curve (AUC) was computed to determine the discriminatory ability of the nucleocapsid-containing assay for identification of recent infection. Participants had a mean age of 40 (range=23-66) years, 83% were female. Round 1 seroprevalence was 9.5%. Prior to round 2 testing, 46% reported vaccination. Among those not recently infected, when comparing vaccinated vs. unvaccinated individuals, elevated levels of spike 1 (p<0.001) and spike 2 (p=0.01) were observed while nucleocapsid levels were not statistically significantly different (p=0.90). Among all participants, nucleocapsid response predicted recent infection with an AUC(95%CI) of 0.93(0.88,0.99). Among individuals vaccinated >10 days prior to antibody testing, the specificity of the nucleocapsid-containing assay was 92% and while the specificity of the spike-only assay was 0%. An IgG assay identifying reactivity to nucleocapsid protein is an accurate predictor of natural infection among a partially vaccinated population while a spike-only assay performed poorly.
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Abstract: Objective: This study was conducted to determine whether installation of sit-stand desks (SSDs) could lead to decreased sitting time during the workday among sedentary office workers. Methods: A randomized cross-over trial was... more
Abstract: Objective: This study was conducted to determine whether installation of sit-stand desks (SSDs) could lead to decreased sitting time during the workday among sedentary office workers. Methods: A randomized cross-over trial was conducted from January to April, 2012 at a business in Minneapolis. 28 (nine men, 26 full-time) sedentary office workers took part in a 4 week intervention period which included the use of SSDs to gradually replace 50 % of sitting time with standing during the workday. Physical activity was the primary outcome. Mood, energy level, fatigue, appetite, dietary intake, and productivity were explored as secondary outcomes. Results: The intervention reduced sitting time at work by 21 % (95 % CI 18%–25%) and sedentary time by 4.8 min/work-hr (95 % CI 4.1–5.4 min/work-hr). For a 40 h work-week, this translates into replacement of 8 h of sitting time with standing and sedentary time being reduced by 3.2 h. Activity level during non-work hours did not change. ...
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Objective This study aimed to examine the effect on continuously monitored blood glucose (BG) among participants with impaired fasting glucose (IFG) who used a height-adjustable desk while working. Methods The study was a... more
Objective This study aimed to examine the effect on continuously monitored blood glucose (BG) among participants with impaired fasting glucose (IFG) who used a height-adjustable desk while working. Methods The study was a repeated-measures pilot study in overweight or obese women who had IFG (BG >100 mg·dL−1) and a sedentary job. BG was monitored with continuous glucose monitoring devices during two 1-wk periods at work: 1 wk in the seated position and 1 wk using alternate bouts of sitting and standing (by adjusting their desks) throughout the workday. Results Ten women completed the study. Sedentary time significantly predicted BG independently of diet and overall physical activity (P = 0.02). Dietary carbohydrates, protein, and fat were significant predictors of BG (P < 0.001). Conclusions Sedentary time is a strong predictor of increased BG in women with IFG and a sedentary job.
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SOURCE CITATION Favresse J, Gillot C, Oliveira M, et al. Head-to-head comparison of rapid and automated antigen detection tests for the diagnosis of SARS-CoV-2 infection. J Clin Med. 2021;10:265. 33450853.
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Physical activity is beneficial for many aspects of health but is associated with a risk of injury. Studies that assess causal risk factors of injury and reinjury provide valuable information to help develop and improve injury prevention... more
Physical activity is beneficial for many aspects of health but is associated with a risk of injury. Studies that assess causal risk factors of injury and reinjury provide valuable information to help develop and improve injury prevention programs. However, the underlying assumptions of analytical approaches often used to estimate causal factors in injury and subsequent injury research are often violated. This means that ineffective or even harmful interventions could be proposed because the underlying analyses produced unreliable or invalid causal effect estimates. We describe an adapted version of the multistate framework [multistate framework for the analysis of subsequent injury in sport (M‐FASIS)] that makes investigator choices more transparent with respect to outcome and healing time. In addition, M‐FASIS incorporates all previous sport injury analytical frameworks and accounts for injuries or conditions that heal or do not heal to 100%, acute and overuse injuries, illnesses, ...
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Obesity is associated with several cardiac structural, functional, hemodynamic, and neurohormonal changes, resulting in increased risk for cardiovascular diseases (CVDs). Particularly, obesity is associated with greater risk for heart... more
Obesity is associated with several cardiac structural, functional, hemodynamic, and neurohormonal changes, resulting in increased risk for cardiovascular diseases (CVDs). Particularly, obesity is associated with greater risk for heart failure, hypertension, coronary heart disease, atrial fibrillation, and more recently, pulmonary arterial hypertension. Once such diseases have been diagnosed, however, patients with obesity present a more favorable prognosis compared to leaner patients. Such a phenomenon has been defined as “the obesity paradox.” The mechanisms leading to improved outcomes in obese patients are still largely unknown; however, most of the studies investigating the role of obesity on the development and progression of CVD were limited by the use of the body mass index, which does not distinguish between different body composition (BC) compartments, which have distinctive effects on the CV system. In this review, we will discuss the increased risk of CVD in patients with...
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Because of their frequent encounters with sedentary patients, family physicians are poised to be on the forefront of the medical community’s response to physical inactivity. The purpose of this pilot study was to examine whether the... more
Because of their frequent encounters with sedentary patients, family physicians are poised to be on the forefront of the medical community’s response to physical inactivity. The purpose of this pilot study was to examine whether the addition of a pedometer to brief physician counseling could help patients in-crease their ambulatory activity. Ninety four participants recruited from a family medicine clinic were randomly assigned to 2 groups. Both groups received a brief physician endorsement of regular physical activity, a handout on the benefits of an active lifestyle, and 3 follow-up phone calls from a health edu-cator. In addition, the intervention group received a pedometer and was instructed to record their steps daily over the 9-week study period. Measurements were taken for self-reported walking, walking stage-of-change, walking self-efficacy, and pedometer steps (intervention group only). Among completers, mean daily step counts in the pedometer group rose from 6779 at baseli...
A major objective of sport medicine research is to assess causes of injuries. Studying causes of subsequent injuries, including the effects of rehabilitation programs, presents unique challenges to provide appropriate guidance for... more
A major objective of sport medicine research is to assess causes of injuries. Studying causes of subsequent injuries, including the effects of rehabilitation programs, presents unique challenges to provide appropriate guidance for treatment. In this commentary, we highlight the issue of “collider stratification bias”. Collider stratification bias is a major concern whenever we restrict populations based on variables that have multiple causes, which is common in surveillance programs studying subsequent injuries.
Objective: The primary aim of this study is to evaluate the prevalence of diabetes mellitus (DM) in patients seen with adhesive capsulitis (Frozen Shoulder, FS). Our secondary aim is to assess the prevalence of thyroid disease in these... more
Objective: The primary aim of this study is to evaluate the prevalence of diabetes mellitus (DM) in patients seen with adhesive capsulitis (Frozen Shoulder, FS). Our secondary aim is to assess the prevalence of thyroid disease in these same patients. Design: A retrospective chart review. Setting: Orthopedics and Sports Medicine Clinics in the Minnesota-Fairview Network from 2009-2020. Participants: 638 patients (417 Females and 221 Males) Independent Variables: Frozen shoulder (FS) Main Outcome Measures: Diabetes mellitus (DM) or thyroid disease Results: Of the 638 FS patients, the total prevalence of DM was 49.8% (318/638). Among the 417 females with FS, 202 (48.4%) had DM. Among the 221 Male patients with FS, 116 (52.5%) had DM. The total prevalence of thyroid disease in frozen shoulder patients was 17.7% (113/638). Conclusion: Among those seen for FS, approximately one-half also suffered from DM and approximately one-fifth suffered from a thyroid condition. Our results suggest th...
We read with interest the study by Fekri et al. [1], “Association of body mass index with life expectancy with and without cardiovascular disease” (CVD). This letter demonstrates that some of their findings may be the result of selection... more
We read with interest the study by Fekri et al. [1], “Association of body mass index with life expectancy with and without cardiovascular disease” (CVD). This letter demonstrates that some of their findings may be the result of selection bias, even though the study involved a large, seemingly unselected population-based cohort. Selection bias can occur not only during study design or recruitment, but also through restriction or conditioning in the analysis [2, 3]. The study findings can be summarized as follows:
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The purpose of this editorial is to provide a compendium of injury rates calculated by both athlete-at-risk and athlete-exposure methods across a wide variety of sports so future investigators can compare their results to the literature... more
The purpose of this editorial is to provide a compendium of injury rates calculated by both athlete-at-risk and athlete-exposure methods across a wide variety of sports so future investigators can compare their results to the literature using different methods. When available, the compendium includes results for preseason, in-season and postseason games and practices.