Visualizing External Validity: Graphical Displays to Inform the Extension of Treatment Effects from Trials to Clinical Practice.

BACKGROUND: In the presence of effect measure modification, estimates of treatment effects from randomized controlled trials may not be valid in clinical practice settings. The development and application of quantitative approaches for extending treatment effects from trials to clinical practice settings is an active area of research. METHODS: In this article, we provide researchers with a practical roadmap and four visualizations to assist in variable selection for models to extend treatment effects observed in trials to clinical practice settings and to assess model specification and performance. We apply this roadmap and visualizations to an example extending the effects of adjuvant chemotherapy (5-fluorouracil vs. plus oxaliplatin) for colon cancer from a trial population to a population of individuals treated in community oncology practices in the United States. RESULTS: The first visualization screens for potential effect measure modifiers to include in models extending trial treatment effects to clinical practice populations. The second visualization displays a measure of covariate overlap between the clinical practice populations and the trial population. The third and fourth visualizations highlight considerations for model specification and influential observations. The conceptual roadmap describes how the output from the visualizations helps interrogate the assumptions required to extend treatment effects from trials to target populations. CONCLUSIONS: The roadmap and visualizations can inform practical decisions required for quantitatively extending treatment effects from trials to clinical practice settings.

Introducing longitudinal cumulative dose to describe chemotherapy patterns over time: Case study of a colon cancer trial.

Adjuvant chemotherapy regimens take months to complete. Despite this, studies evaluate chemotherapy adherence via measures assessed at the end of treatment (eg, number of patients missing any dose, relative dose intensity [RDI]). This approach ignores information like the timing of treatment delays. We propose longitudinal cumulative dose (LCD) to integrate impacts of dose reductions, missed doses and dose delays over time. We obtained data from the 2246 participants in the MOSAIC trial randomized to FOLFOX (all three agents) or 5-FU/LV (only 5-fluorouracil and leucovorin). We evaluated proportions of patients stopping treatment early and reducing, missing or delaying a dose in each arm for each chemotherapy agent at each cycle. We calculated LCD, the fraction of the final standard dose a participant reached by a given day, for each participant and each agent and compared it over time and at 24 weeks between treatment arms. Participants randomized to FOLFOX were more likely to stop treatment, reduce doses, miss doses or delay cycles; these differences increased over time. Median LCD for oxaliplatin in the FOLFOX arm at 24 weeks was 77%. The LCD for 5-fluorouracil differed between arms (FOLFOX arm median: 81%; 5-FU/LV arm median: 96%). Visualizing LCD highlighted the timing of deviations from standard administration in a way RDI could not, with major differences in 5-fluorouracil LCD across treatment arms beginning after the sixth dose. Further evaluation of LCD and its impacts on clinical outcomes may clarify mechanisms for heterogeneous patient outcomes.

Body mass index, calcium supplementation and risk of colorectal adenomas.

Calcium supplementation (1,200 mg/day) did not significantly reduce colorectal adenomas in our recent randomized, controlled trial (Vitamin D/Calcium Polyp Prevention Study, VCPPS, 2004-2013) in contrast to our previous trial (Calcium Polyp Prevention Study, CPPS, 1988-1996). To reconcile these findings, we identified participant characteristics that differed between the study populations and modified the effect of calcium supplementation on adenomas or high-risk findings (advanced or multiple adenomas). Compared to the CPPS, more participants in the VCPPS were obese (body mass index (BMI) ≥30 kg/m2 ; 37.5% vs. 24.4%) and fewer had normal BMI (BMI <25 kg/m2 ; 18.5% vs. 31%). BMI appeared to modify the effect of calcium supplementation on adenomas and especially on high risk-findings: in the VCPPS, there was a 44% reduction in high-risk findings among individuals whose BMI was normal (RR = 0.56, 95% CI = 0.26-1.23), but not among overweight (RR = 1.09, 95% CI = 0.62-1.91) or obese (RR = 1.54, 95% CI = 0.92-2.57) individuals (pinteraction = 0.03). Similarly, in the CPPS, there was a 56% reduction in high-risk findings among individuals whose BMI was normal (RR = 0.44, 95% CI = 0.26-0.74), but not among overweight (RR = 0.87, 95% CI = 0.55-1.39) or obese (RR = 1.02, 95% CI = 0.57-1.82) individuals (pinteraction = 0.02). Standardization of each trial's findings to the BMI distribution in the other attenuated calcium's protective effect on adenomas in the CPPS but enhanced it in the VCPPS. In conclusion, 1,200 mg/day calcium supplementation may reduce risk of colorectal adenomas among those with normal BMI but not in overweight or obese individuals; and differences in BMI distribution partially account for the apparent difference in calcium efficacy between the two trials.

Effect of Postnatal HIV Treatment on Clinical Mastitis and Breast Inflammation in HIV-Infected Breast-feeding Women.

BACKGROUND: The relationship between mastitis and antiretroviral therapy among HIV-positive, breast-feeding women is unclear. METHODS: In the Breastfeeding, Antiretrovirals, and Nutrition (BAN) study, conducted in Lilongwe, Malawi, 2369 mother-infant pairs were randomized to a nutritional supplement group and to one of three treatment groups: maternal antiretroviral therapy (ART), infant nevirapine (NVP) or standard of care for 24 weeks of exclusive breast-feeding and 4 weeks of weaning. Among 1472 HIV-infected women who delivered live infants between 2004 and 2007, we estimated cumulative incidence functions and sub-distribution hazard ratios (HR) of mastitis or breast inflammation comparing women in maternal ART (n = 487) or infant nevirapine (n = 492) groups to the standard of care (n = 493). Nutritional supplement groups (743 took, 729 did not) were also compared. RESULTS: Through 28-weeks post-partum, 102 of 1472 women experienced at least one occurrence of mastitis or breast inflammation. The 28-week risk was higher for maternal ART (risk difference (RD) 4.5, 95% confidence interval (CI) 0.9, 8.1) and infant NVP (RD 3.6, 95% CI 0.3, 6.9) compared to standard of care. The hazard of late-appearing mastitis or breast inflammation (from week 5-28) was also higher for maternal ART (HR 6.7, 95% CI 2.0, 22.6) and infant NVP (HR 5.1, 95% CI 1.5, 17. 5) compared to the standard of care. CONCLUSIONS: Mastitis or breast inflammation while breast-feeding is a possible side effect for women taking prophylactic ART and women whose infants take NVP, warranting additional research in the context of postnatal HIV transmission.