Validity and Reliability of the Antepartum Gastrointestinal Symptom Assessment Instrument

Objective: To examine the psychometric properties of the nine-item Antepartum Gastrointestinal Symptom Assessment (AP-GI-SA) instrument.

Design: Single-group prospective design.

Setting: Urban prenatal clinic serving a diverse population.

Participants: Convenience sample of 45 pregnant women.

Methods: Participants completed the AP-GI-SA before a scheduled prenatal care appointment. We used Bayesian structural equation modeling to evaluate the construct validity of the scale and assessed known-groups validity. We assessed reliability through maximal reliability coefficient estimate and measured internal consistency with Cronbach's alpha coefficient.

Results: Participants completed the instrument in 2 minutes or less. Construct validity was supported by confirmatory factor analysis (posterior predictive p value = 0.49, gamma-hat = 0.970, and root mean square error of approximation = 0.065), which indicated that the single-factor model is a plausible data-generative model for GI symptoms. The maximal reliability coefficient of 0.75 and Cronbach's alpha coefficient of 0.67 supported reliability. Average AP-GI-SA scores were the highest for women in the third trimester. Of all nine GI symptoms, heartburn in the third trimester received the highest score.

Conclusion: Our findings provide preliminary support for the validity and reliability of the AP-GI-SA. The instrument may be used as a measure in intervention studies where GI symptoms of pregnancy are an outcome. The AP-GI-SA could also be useful in clinical settings to quickly evaluate GI symptoms.