3.1.1. Time of Follow-Up and Drop-Out

Mean duration of follow-up in this cohort was 1.59 ± 1.60 years, with 59.9% patients stopping it unilaterally and 33.5% requesting the end of follow-up in their last visit (mainly due to the achievement of BMI or metabolic improvement). A progressive decrease in the study population was observed throughout follow-up with only 21 patients (7% of initial cohort) completing 7 years of follow-up (Figure 1). The drop-out rate before 6 months of follow-up was higher in Latinos (52% vs. 24% in Caucasians; *p* < 0.001), males (36% vs. 23% in females; *p* < 0.05) and prepubertal (32% vs. 26% in pubertal; *p* < 0.05). After 1 year, the interethnic difference in attrition rate persisted (47% in Latinos vs. 18% in Caucasians; *p* < 0.001). Among the patients dropping out, 84.1% had repeatedly not fulfilled the therapeutic recommendations in the visits prior to withdrawal and 5.4% argued familial/social difficulties. A total of 8% of the patients re-consulted after follow-up had stop (most after regaining lost weight).

It is of note that, among the patients abandoning follow-up, 11.2% did it after the initial clinical examination (not performing the complementary tests indicated) and 32.5% after their second visit once they received the results from the complementary examinations (total 43.7% patients abandoned prior to their third visit).

**Figure 1.** Evolution of patient retainment and their standardized BMI (expressed as SDS) throughout follow-up to a maximum of 7 years from their first evaluation. *Abbreviations:* BMI-SDS: Standardized body mass index (Z-score); F-U: Follow-up; n: number of patients retaining follow-up.
