Background Low-carbohydrate ketogenic diets are a viable method to lose weight that have regained popularity in recent years. Technology in the form of mobile health (mHealth) apps allows for scalable and remote delivery of such dietary interventions and are increasingly being used by the general population without direct medical supervision. However, it is currently unknown which factors related to app use and user behavior are associated with successful weight loss. Objective First, to describe and characterize user behavior, we aim to examine characteristics and user behaviors over time of participants who were enrolled in a remotely delivered clinical weight loss trial that tested an mHealth ketogenic diet app paired with a breath acetone biofeedback device. Second, to identify variables of importance to weight loss at 12 weeks that may offer insight for future development of dietary mHealth interventions, we aim to explore which app- and adherence-related user behaviors characterized successful weight loss. Methods We analyzed app use and self-reported questionnaire data from 75 adults with overweight or obesity who participated in the intervention arm of a previous weight loss study. We examined data patterns over time through linear mixed models and performed correlation, linear regression, and causal mediation analyses to characterize diet-, weight-, and app-related user behavior associated with weight loss. Results In the context of a low-carbohydrate ketogenic diet intervention delivered remotely through an mHealth app paired with a breath acetone biofeedback device, self-reported dietary adherence seemed to be the most important factor to predict weight loss (β=–.31; t54=–2.366; P=.02). Furthermore, self-reported adherence mediated the relationship between greater app engagement (from c=–0.008, 95% CI –0.014 to –0.0019 to c’=–0.0035, 95% CI –0.0094 to 0.0024) or higher breath acetone levels (from c=–1.34, 95% CI –2.28 to –0.40 to c’=–0.40, 95% CI –1.42 to 0.62) and greater weight loss, explaining a total of 27.8% and 28.8% of the variance in weight loss, respectively. User behavior (compliance with weight measurements and app engagement) and adherence-related aspects (breath acetone values and self-reported dietary adherence) over time differed between individuals who achieved a clinically significant weight loss of >5% and those who did not. Conclusions Our in-depth examination of app- and adherence-related user behaviors offers insight into factors associated with successful weight loss in the context of mHealth interventions. In particular, our finding that self-reported dietary adherence was the most important metric predicting weight loss may aid in the development of future mHealth dietary interventions. Trial Registration ClinicalTrials.gov NCT04165707; https://clinicaltrials.gov/ct2/show/NCT04165707 International Registered Report Identifier (IRRID) RR2-10.2196/19053

Background: Clinical utility of cardiac biomarker testing during pregnancy in women with preexisting cardiac disease is not well known. We studied the levels and temporal trends of NT-proBNP (N-terminal pro-B-type natriuretic peptide) and hs-cTnI (high-sensitivity cardiac troponin I) throughout pregnancy in women with preexisting cardiac disease and sought to assess the association between NT-proBNP and hs-cTnI and pregnancy outcomes. Methods: Three hundred seven pregnant women with preexisting cardiac disease were prospectively recruited. Mixed-effects linear regression analysis was used to compare the NT-proBNP and hs-cTnI levels between time periods and subgroups. Logistic regression analysis adjusted for maternal age and CARPREG II (Cardiac Disease in Pregnancy) risk score assessed the association between NT-proBNP levels and adverse events. Results: Geometric mean NT-proBNP (95% CI) was stable through pregnancy with a transient significant increase with labor and delivery (101.4 pg/mL [87.1–118.1], 90.2 pg/mL [78.5–103.6], 153.6 pg/mL [126.8–186.1], and 112.2 pg/mL [94.2–133.7] for first/second trimester, third trimester, labor/delivery and postpartum, respectively). We observed a statistically significant difference in the NT-proBNP between women with preserved versus decreased systemic ventricular function, structurally normal versus abnormal heart, modified World Health Organization class 1, 2 versus modified World Health Organization class 3, 4 and no congenital heart disease versus congenital heart disease. Compared to those without events, median (interquartile range) NT-proBNP levels were significantly higher in those who had heart failure (204 pg/mL [51–450] versus 55 pg/mL [31–97]; P =0.001) and preeclampsia (98 pg/mL [40–319] versus 55 pg/mL [31–99]; P =0.027). NT-proBNP, adjusted for age and CARPREG II risk score, was significantly associated with combined heart failure and preeclampsia (adjusted odds ratio, 2.14 [95% CI, 1.48–3.10] per log NT-proBNP increase; P <0.001). NT-proBNP <200 pg/mL had a specificity of 91% and negative predictive value of 95% in predicting combined heart failure and preeclampsia. Conclusions: NT-proBNP remains steady over the course of pregnancy with a transient increase during labor and delivery with higher levels in subgroups of stable cardiac patients. NT-proBNP level of 200 pg/mL can be used in the diagnosis of heart failure/preeclampsia in the pregnant cardiac population.

Background While treatment guidelines for HIV in adults have evolved rapidly with the advent of new antiretroviral (ARV) treatment, those for the prevention of vertical HIV transmission in pregnancy have evolved more slowly due to safety and efficacy concerns. Here we describe Canadian prescribing patterns for ARV treatments during pregnancy and compare them to perinatal HIV prescribing guidelines of the United States Department of Health and Human Services (HHS), that are commonly used in Canada and include recommendations for newly commercialized therapies. Methods The Canadian Perinatal HIV Surveillance Program (CPHSP) captures annual medical data on mothers living with HIV and their infants from 23 sites across Canada. Women from this cohort who received an ARV treatment during pregnancy and who gave birth between 2004 and 2020 were included in the study. ARV treatments were designated as ‘preferred/alternative’ as per HHS HIV perinatal guidelines, or ‘other than preferred/alternative’. Results We identified 3673 pregnancies from 2720 women. The proportion of women that conceived while on ARV treatment increased from 29% in 2003 to 90% in 2020. Other than preferred/alternative ARV treatments were received in 1112 (30%) of pregnancies and this was significantly associated with having initiated ARV treatment before conception. Conclusion In Canada during the study period, a high number of women were prescribed an other than preferred/alternative ARV treatment during pregnancy. Further optimization of ARV treatment in women of childbearing age living with HIV is warranted.

Objective To evaluate the impact of type and timing of antiretroviral therapy (ART) on the risk of preterm delivery (PTD) and small‐for‐gestational age (SGA) birth among pregnant women and people living with HIV in Canada. Methods Data for this retrospective cohort study were analyzed from the Canadian Perinatal HIV Surveillance Program from 1990 to 2020. The association between ART and risk of PTD (<37 weeks) and SGA birth (<10th percentile) was explored using mixed effects logistic regression and time‐dependent Cox proportional hazards models. Results Overall, there were 14.9% (654 of 4379) PTD and 18.5% (732 of 3947) SGA cases. A higher risk of PTD was observed with nonnucleoside reverse transcriptase inhibitor–(adjusted hazard ratio [aHR], 1.73; P = 0.019) and boosted protease inhibitor– (aHR, 186; P = 0.007) based regimens compared with integrase strand transfer inhibitor (INSTI)–based regimens. ART initiation prior to conception was associated with a lower risk of SGA birth compared with ART initiation after conception at 1 to 14 weeks (adjusted odds ratio [aOR], 0.69; P = 0.024) and > 14 weeks (aOR, 0.70; P = 0.005). Conclusion INSTI‐based ART regimens were associated with lower risk of PTD compared with other regimens, and ART initiation before conception was associated with a lower risk of SGA birth. These findings, with overall safety data, should be considered when providing pregnancy counseling to people living with HIV.