Objective

To investigate whether the presence or absence of improvement in chronic severe functional constipation (CSFC) at the early stage of treatment with electroacupuncture predicts subsequent response or nonresponse, and to determine the optimal treatment duration as assessing electroacupuncture subsequent responses.

Methods

This is a post-hoc analysis using data pooled from two large-scale randomized controlled trials. Patients with CSFC were recruited, and those in the electroacupuncture groups were included in the present study. Early improvement was defined as a weekly increase of ≥ 1 complete spontaneous bowel movement (CSBM) compared to baseline. Three treatment response criteria were evaluated: ≥ 3 CSBMs per week, overall CSBM response, and sustained CSBM response. Predictive statistics, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), were calculated at weeks 1 to 4. Receiver operating characteristic (ROC) curves and accuracy rates were used to determine the optimal time point for differentiation between responders and non-responders.

Results

A total of 813 participants who received electroacupuncture were analyzed. The proportion of improvers was 40.34% by week 1, increasing to 52.52% by week 4. After 8 weeks of treatment, the response rates were 30.14%, 25.83%, and 25.58% according to the three aforementioned criteria, respectively. Early improvement was a strong predictor of treatment response, with week 3 demonstrating the highest predictive accuracy.

Conclusion

Early improvement with electroacupuncture, especially at week 3, can predict subsequent outcomes. Our findings suggest that acupuncturists may identify non-responders who might require adjustments to therapeutic strategies early in treatment.

Key words: Chronic severe functional constipation, Electroacupuncture, Early improvement, Prediction, Treatment response