Publications

Phylogeographic methods can help reveal the movement of genes between populations of organisms. This has been widely done to quantify pathogen movement between different host populations, the migration history of humans, and the geographic spread of languages or gene flow between species using the location or state of samples alongside sequence data. Phylogenies therefore offer insights into migration processes not available from classic epidemiological or occurrence data alone. Phylogeographic methods have however several known shortcomings. In particular, one of the most widely used methods treats migration the same as mutation, and therefore does not incorporate information about population demography. This may lead to severe biases in estimated migration rates for data sets where sampling is biased across populations. The structured coalescent on the other hand allows us to coherently model the migration and coalescent process, but current implementations struggle with complex data sets due to the need to infer ancestral migration histories. Thus, approximations to the structured coalescent, which integrate over all ancestral migration histories, have been developed. However, the validity and robustness of these approximations remain unclear. We present an exact numerical solution to the structured coalescent that does not require the inference of migration histories. Although this solution is computationally unfeasible for large data sets, it clarifies the assumptions of previously developed approximate methods and allows us to provide an improved approximation to the structured coalescent. We have implemented these methods in BEAST2, and we show how these methods compare under different scenarios.

BACKGROUND

Attention to symptoms of weight gain and dyspnea are central tenets of patient education in heart failure (HF). However, it is not known whether diary use improves patient outcomes. The aims of this study were to compare mortality among rural patients with HF who completed versus did not complete a daily diary of weight and symptom self-assessment and to identify predictors of diary use.

METHODS AND RESULTS

This is a secondary analysis of a 3-arm randomized controlled trial on HF education of self-care with 2 intervention groups versus control who were given diaries for 24 months to track daily weight, HF symptoms, and response to symptom changes. Mean age was 66±13, 58% were men, and 67% completed diaries (n=393). We formed 5 groups (no use, low, medium, high, and very high) based on the first 3 months of diary use and then analyzed time to event (cardiac mortality, all-cause mortality, and HF-related readmission) starting at 3 months. Compared with patients with no diary use, high and very high diary users were less likely to experience all-cause mortality (=0.02 and =0.01, respectively). Self-reported sedentary lifestyle was associated with less diary use in an adjusted model (odds ratio, 0.66; 95% confidence interval, 0.46-0.95; =0.03). Depression and sex were not significant predictors of diary use in the adjusted model.

CONCLUSIONS

In this study of 393 rural patients with HF, we found that greater diary use was associated with longer survival. These findings suggest that greater engagement in self-care behaviors is associated with better HF outcomes.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique Identifier: NCT00415545.