Background and Aims

Amitriptyline improves symptoms in functional abdominal pain disorders (FAPD) in adults with variable results in pediatric studies. The study aims to evaluate the efficacy of amitriptyline in pediatric FAPD.

Methods

In this open-label trial, children (≤18 years) diagnosed as FAPD based on ROME IV criteria were randomized to amitriptyline or placebo for 12 weeks. Post-treatment improvement of pain and quality of life (QOL) from the baseline were compared between the two groups.

Results

The mean age of 149 children (amitriptyline 75, placebo 74) was 11.3±3.5 years (79 boys). There was a significant difference in pain improvement in terms of reduction in scores for intensity (3.4 vs. 0.9), frequency (3.6 vs. 0.6), duration (3.5 vs. 0.9), and QOL (2.3 vs. 0.9) between amitriptyline and placebo group (p<0.001 in all). Responders (>50% reduction) in pain was seen in 76% in amitriptyline compared to 14.9% in the placebo group (p<0.001). On multivariate analysis, the use of amitriptyline was the only factor predictive of response (OR 24.1, 95% CI: 9.1-64.6, p< 0.001). Minor adverse events were comparable between the groups (25.3% vs. 13.5% respectively, p=0.07). 89% of children (24/27) who had extended treatment duration (6.8±1.8 months) had pain improvement. After discontinuation of amitriptyline, 70 % had sustained response over a mean follow-up of 15.84±5.6 months.

Conclusions

A three-month trial of amitriptyline gives sustained relief of pain in two-thirds of children with FAPD. The safety profile of the drug and its efficacy necessitate more frequent use in the clinical settings.