The NVP QOL Questionnaire: Psychometric properties of the self-report measure of health-related quality of life for nausea and vomiting during pregnancy.

Abstract

The Nausea and Vomiting of Pregnancy Quality of Life (NVP QOL) Questionnaire is a self-report measure of health-related QOL for nausea and vomiting during pregnancy. This study determines the best fitting factor structure for the NVP QOL Questionnaire and explores its measurement invariance in terms of observation time and parity. A test-retest study of pregnant women was conducted at Gestational Weeks (GWs) 10-13 (T1: N = 381) and 1 week later (T2: n = 128) at one hospital and five clinics with the NVP QOL and the Pregnancy-Unique Quantification of Emesis and Nausea (PUQE). Exploratory and confirmatory factor analyses were performed to compare different factor structure models and evaluate measurement invariance of the best fitting model between two time points and between primiparas and multiparas. Concurrent validity of the NVP QOL was clarified by correlations with the PUQE, Sheehan Disability Scale, and other scales. The one-factor model had the best fit. This factor structure model was acceptable up to the factor invariance level for two time points and up to the factor mean level for primiparas versus multiparas. Correlations between NVP QOL, PUQE, and Sheehan Disability Scale scores were strong. Women with higher NVP QOL scores were more likely to lose weight, have lower daily fluid intake, have reduced fluid and food intake since pregnancy began, and receive outpatient or inpatient treatment. The one-factor structure and measurement invariance of the NVP QOL at different times and parities were demonstrated, suggesting that the NVP QOL can be used to evaluate primiparas and multiparas in a longitudinal study.