Evidence-Based Classification for Post-bariatric Weight Regain from a Benchmark Registry Cohort of 18,403 Patients and Comparison with Current Criteria.

INTRODUCTION: There is a need for a standardized, evidence-based classification of post-bariatric weight-regain, to investigate and compare revision procedures and to advice and treat patients in an evidence-based way. METHODS: We used standard deviations (SD) of the highest (1-2 years) and latest (> 2 years) percentage total weight loss (%TWL) results after primary bariatric surgery from the Dutch Audit for Treatment of Obesity (DATO) bariatric registry as benchmarks for (above) average (≥ - 1SD), poor (- 1SD to - 2SD) and insufficient (< - 2SD) weight loss. Weight regain maintaining (above) average weight loss was called grade 1, weight regain towards poor weight loss grade 2, towards insufficient weight loss grade 3, with subgrades 2a/3a for below average weight loss from the start, and 2b/3b for weight regain from (above) average to below average weight loss. Patient characteristics and diabetes improvement/impairment were compared. Sensitivity and specificity of 14 existing weight regain criteria were calculated. RESULTS: We analyzed 93,465 results from 38,830 patients (77.1% gastric bypass, 22.5% sleeve gastrectomy). The - 1SD thresholds for early and late weight loss approximated 25%TWL and 20%TWL, the - 2SD threshold for late weight loss 10%TWL. Weight regain could be analyzed for 18,403 patients (2.5-5.2 years follow-up). They regained mean 6.7 kg (5.4%TWL), with 66.8% grade 1 weight regain, 7.2% grade 2a, 7.4% grade 2b, 2.1% grade 3a, and 0.6% grade 3b. There were significant differences in comorbidities, gender, age, weight regain, diabetes impairment, and diabetes improvement across grades. Weight regain criteria from literature were extremely divers. None had high sensitivity. CONCLUSION: The DATO classification for post-bariatric weight regain combines the extent of weight regain with evidence-based endpoints of weight loss. It differentiated weight regain maintaining (above) average weight loss, two intermediate grades, gradual weight regain with below average weight loss from the start (primary non-response) and steep weight regain towards insufficient weight loss (secondary non-response). The classification is superior to existing criteria and well supported by evidence.

Predicting dispersal of auto-gyrating fruit in tropical trees: a case study from the Dipterocarpaceae.

Seed dispersal governs the distribution of plant propagules in the landscape and hence forms the template on which density-dependent processes act. Dispersal is therefore a vital component of many species coexistence and forest dynamics models and is of applied value in understanding forest regeneration. Research on the processes that facilitate forest regeneration and restoration is given further weight in the context of widespread loss and degradation of tropical forests, and provides impetus to improve estimates of seed dispersal for tropical forest trees. South-East Asian lowland rainforests, which have been subject to severe degradation, are dominated by trees of the Dipterocarpaceae family which constitute over 40% of forest biomass. Dipterocarp dispersal is generally considered to be poor given their large, gyration-dispersed fruits. However, there is wide variability in fruit size and morphology which we hypothesize mechanistically underpins dispersal potential through the lift provided to seeds mediated by the wings. We explored experimentally how the ratio of fruit wing area to mass ("inverse wing loading," IWL) explains variation in seed dispersal kernels among 13 dipterocarp species by releasing fruit from a canopy tower. Horizontal seed dispersal distances increased with IWL, especially at high wind speeds. Seed dispersal of all species was predominantly local, with 90% of seed dispersing <10 m, although maximum dispersal distances varied widely among species. We present a generic seed dispersal model for dipterocarps based on attributes of seed morphology and provide modeled seed dispersal kernels for all dipterocarp species with IWLs of 1-50, representing 75% of species in Borneo.