Risk Adjusting Health Care Provider Collaboration Networks.

OBJECTIVES: The quality of hospital discharge care and patient factors (health and sociodemographic) impact the rates of unplanned readmissions. This study aims to measure the effects of controlling for the patient factors when using readmission rates to quantify the weighted edges between health care providers in a collaboration network. This improved understanding may inform strategies to reduce hospital readmissions, and facilitate quality-improvement initiatives. METHODS: We extracted 4 years of patient, provider, and activity data related to cardiology discharge workflow. A Weibull model was developed to predict the risk of unplanned 30-day readmission. A provider-patient bipartite network was used to connect providers by shared patient encounters. We built collaboration networks and calculated the Shared Positive Outcome Ratio (SPOR) to quantify the relationship between providers by the relative rate of patient outcomes, using both risk-adjusted readmission rates and unadjusted readmission rates. The effect of risk adjustment on the calculation of the SPOR metric was quantified using a permutation test and descriptive statistics. RESULTS: Comparing the collaboration networks consisting of 2,359 provider pairs, we found that SPOR values with risk-adjusted outcomes are significantly different than unadjusted readmission as an outcome measure (p-value = 0.025). The two networks classified the same provider pairs as high-scoring 51.5% of the time, and the same low scoring provider pairs 85.6% of the time. The observed differences in patient demographics and disease characteristics between high-scoring and low-scoring provider pairs were reduced by applying the risk-adjusted model. The risk-adjusted model reduced the average variation across each individual's SPOR scored provider connections. CONCLUSIONS: Risk adjusting unplanned readmission in a collaboration network has an effect on SPOR-weighted edges, especially on classifying high-scoring SPOR provider pairs. The risk-adjusted model reduces the variance of providers' connections and balances shared patient characteristics between low- and high-scoring provider pairs. This indicates that the risk-adjusted SPOR edges better measure the impact of collaboration on readmissions by accounting for patients' risk of readmission.

Associations between mammographic density and serum and dietary cholesterol.

Although high mammographic density is a risk factor for postmenopausal breast cancer, its etiology remains unclear. We examined whether serum and dietary cholesterol, which increase breast cancer risk and are involved in endogenous estrogen formation, were associated with increased mammographic density. We conducted a cross-sectional analysis of 302 healthy, sedentary postmenopausal women, aged 50-74 years, enrolled in the Alberta Physical Activity and Breast Cancer Prevention Trial between 2003 and 2006. In multiple linear regression models, no significant associations were observed between serum lipids and percent density or dense tissue area (Percent density: b (change in square root percent density per unit change in cholesterol level) = -0.06 (95%CI = -0.26 to 0.13); b = 0.06 (95%CI = -0.48 to 0.61); and b = -0.11 (95%CI = -0.33 to 0.10) for total cholesterol, high-, and low-density lipoprotein, respectively; similar results found for dense area). Alcohol consumption modified the association between triglycerides and percent density (>1 drink/day: b = -0.94 (95%CI = -1.79 to -0.10); ≤ 1 drink/day: b = 0.19 (95%CI = -0.12 to 0.50); and no alcohol consumption: b = 0.15 (95%CI = -0.44 to 0.73). We found no evidence indicating any association between dietary and serum cholesterol levels and mammographic density.

The Alberta Physical Activity and Breast Cancer Prevention Trial: quality of life outcomes.

OBJECTIVE: Interventions for disease prevention should also be evaluated for quality of life (QoL) effects. Few exercise trials have examined QoL in the context of primary disease prevention. Here, we report the QoL outcomes from the Alberta Physical Activity and Breast Cancer Prevention (ALPHA) Trial. METHODS: The ALPHA trial was a randomized controlled trial in Calgary and Edmonton, Canada between May 2003 and July 2007 that compared an exercise intervention to a sedentary lifestyle among 320 sedentary, postmenopausal women. The exercise group was asked to perform moderate-to-vigorous intensity aerobic exercise 45 min/day, 5 days/week for 1 year. QoL was assessed by the short form-36 health survey. RESULTS: Compared to the control group, the exercise group maintained significantly better physical functioning (p<0.001), general health (p<0.001), vitality (p=0.002), and bodily pain (p=0.020) by 4-5 points which exceeds the 3.0 minimally important difference for these scales. Changes in body composition partially mediated the intervention effects. Antidepressant use and the presence of comorbidities moderated some intervention effects. CONCLUSIONS: A 1-year moderate-to-vigorous aerobic exercise program prevents declines in the physical aspects of QoL in postmenopausal women. Exercise may have a potentially important advantage for breast cancer prevention compared to other lifestyle or biomedical interventions.