JMIR Publications

ABSTRACT

Background:

Obesity surgery has proven its effectiveness in weight loss. However, after a loss phase of about 12-18 months, between 20 and 40% of patients regain weight.

Objective:

Prediction of weight evolution is therefore, useful for early detection of weight regain.

Methods:

This was a monocentric retrospective study with calculation of the weight trajectory of patients having undergone gastric bypass surgery. Data on 795 patients after an interval of 2 years allowed modelling of weight trajectories according to a hierarchical cluster analysis (HCA) tending to minimize the intragroup distance according to Ward. Clinical judgement was used to finalise the identification of clinically relevant representative trajectories. This modelling was validated on a group of 381 patients for whom the observed weight at 18 months was compared to the predicted weight, and the weights were transformed according to Reinhold’s classification of results.

Results:

Two successive HCA produced 14 representative trajectories, distributed among 4 clinically relevant families: 6 of the 14 weight trajectories decreased systematically over time or decreased, then stagnated; 4 of the 14 trajectories decreased, then increased, then decreased again; 2 of the 14 trajectories decreased, then increased; 2 of the 14 trajectories stagnated at first, then began a decline. A comparison of observed weight and that estimated by modelling made it possible to correctly classify 97.6% of persons with "excess weight loss (EWL) >50% ", and more than 58% of persons with " EWL between 25 and 50% ". In the category of persons with "EWL >50% ", weight data over the first 6 months were adequate to correctly predict the observed result.

Conclusions:

this modelling allowed correct classification of persons with EWL >50%. Other studies are needed to validate this model in other populations, with other types of surgery and other medical-surgical teams.