A long-term follow-up of treatment for young children with obesity: a randomized controlled trial – International Journal of Obesity

From the original sample of 177 children, 6 children were excluded due to developing medical diagnoses incompatible with inclusion criteria. Thus, 171 qualified for the modified intention-to-treat-analysis, 19% (n = 34) had dropped out between enrollment and 48 months (e.g., before baseline, refused to participate), 13% (n = 23) were lost to follow-up (e.g., no contact, moved abroad). At 48 months, 64% (n = 114) of the children had measurements; of those, 54% (n = 61) were measured by the research team and 46% (n = 53) were measured by healthcare professionals, with data collected from medical records. For the 48-month follow-up, measures were collected at mean 50 months, range 38–67 months. See flowchart, Fig. 1. No adverse events were reported.

Baseline characteristics are presented in Table 1. At baseline, the mean (SD) age was 5.3 (0.8) years, BMI-SDS was 3.0 (0.6), BMI was 21.5 (1.9) kg/m² and %IOTF25 was 123.5 (10.6). At the 48-month follow-up, the mean (SD) age was 9.5 (0.8) years, BMI-SDS was 2.6 (0.6), BMI was 25.6 (3.8) and %IOTF25 was 132.9 (19.2). Figure 2 illustrates the individual change in BMI-SDS from baseline to 48 months and Supplementary Table 1 presents the sample’s characteristics at 48 months.

Graphical presentation of individual change in BMI-SDS from baseline to 48 months.

Attendance of clinical visits between 12 and 48 months

Of the 114 children with BMI data (i.e., without imputation), between 12–48 months after treatment initiation, 62% (n = 71) attended at least one clinical appointment for obesity treatment. During the 12–48 months period, the mean (SD) number of hours in obesity treatment was 2.2 (2.4) h (range 0–12 h) with no significant differences between groups (Supplementary Table 2).

Change in weight status (baseline to 48 months)

In all groups, BMI-SDS, mean (95% CI), decreased over time (baseline to 48 months), for PGB −0.45 (−0.73 to −0.18), PGNB −0.34 (−0.55 to −0.13) and ST −0.25 (−0.40 to −0.10), Fig. 3A. No difference was found between groups (p > 0.05), Table 2 and Supplementary Table 3.

A primary outcome BMI-SDS. B Secondary post-hoc outcome %IOTF25. C BMI. D Waist circumference. *P < 0.05 (group difference, ST as a reference in A, B, C, PGNB as a reference in D).

The percentage above the overweight cut-off, mean (95% CI) %IOTF25, increased over time for both PGNB 10.70 (5.70 to 15.70) and ST 11.92 (8.40 to 15.44) but not for PGB 4.50 (−1.64 to 10.63). The increase of %IOTF25 in ST was significant compared to PGB (p = 0.043), no difference between PGNB and PGB was found (p = 0.117), Fig. 3B, Table 2 and Supplementary Table 3.

Over time, for BMI and WC, mean (95% CI) increased for all groups. PGB had an increase of BMI of 2.95 (1.78 to 4.13), PGNB 4.34 (3.37 to 5.29) and ST 4.56 (3.89 to 5.24). PGB had a smaller increase compared to ST (p = 0.022) but similar to PGNB (p = 0.071), Fig. 3C, Table 2. For WC (cm), PGB had an increase of 12.9 (9.7 to 16.2), PGNB 17.3 (14.2 to 20.3) and ST 16.3 (14.2 to 18.4). PGB had a smaller increase than PGNB (p = 0.039) and no difference between PGB and ST was found (p = 0.075), Fig. 3D Table 2 and Supplementary Table 3.

Clinical significance

At 48 months, the probability (95% CI) of a clinically significant ≥0.5 BM-SDS reduction was twice as likely, RR = 2.03 (1.27 to 3.27, p = 0.003), in PGB (53.7%) compared to ST (33.0%). PGNB (46.6%) was not different from ST, RR = 1.51 (0.91 to 2.53, p = 0.113). A reduction of ≥0.25 BMI-SDS score was more likely for both PGB (69.8%) RR = 1.84 (1.31 to 2.60, p < 0.001) and PGNB (62.6%) RR = 1.56 (1.06 to 2.30, p = 0.025) compared to ST (46.7%).

Shift of weight status category

Table 3 describes the observed data (i.e., without imputation) on weight status category at baseline, 12 months and 48 months for PGB, PGNB and ST. In all groups, a shift to an improved weight status was seen. At 48 months, shifting from severe obesity at baseline to normal weight, overweight or obesity occurred in 14% (n = 3) of the children in PGB, 15% (n = 4) in PGNB and 13% (n = 8) in ST. Shifting from obesity to normal or overweight occurred in 19% (n = 4) children in PGB, 12% (n = 3) in PGNB and 15% (n = 9) in ST. No child shifted to a higher weight status category from baseline to 48 months in PGB. However, at 48 months, 8% (n = 5) children in ST had shifted from overweight at baseline to obesity, and one child in PGNB and 7% (n = 4) in ST had shifted from obesity to severe obesity.

Sensitivity analysis

We investigated if variability in attendance had an effect on the overall findings by including number of visits as a covariate to the primary model; however, no significant effect on the results was found (data not shown). Additionally, we separately analysed the timeframe 12 to 48 months; the results were in the same direction as the main model and coefficients can be found in Supplementary Table 4. Socio-demographic factors, included in three-way interaction analysis, had no influence on the results (data not shown). Missing data analysis found that parents who dropped out between 12 and 48 months were slightly older; no other differences were found between complete and missing data (either lost to follow-up or drop-out). Complete case analysis, i.e., without imputation, can be found in Supplementary Table 5. We also conducted a mode of assessor analysis. When comparing measurements collected by the research nurse (n = 61) with those obtained from medical records (n = 53) at 48 months we found that 81% (n = 17) for PGB, 64% (n = 18) for PGNB and 40% (n = 26) for ST were taken by the research nurse. Families in PGB and PGNB had more frequent contact with the research team prior to the 48-month follow-up, which may explain the difference. However, there was no difference in change in BMI-SDS, BMI, WC or IOTF% from baseline to 48 months between research nurse and medical records within PGB and PGNB (p > 0.05). For ST, BMI was mean (95% CI) −1.6 (−3.1 to −0.1, p = 0.033) units lower and IOTF% was −8.0 (−15.1 to −0.9, p = 0.027) percent lower in participants with measurements taken by a research nurse compared to those with measurements from medical records.