Fourteen-item perceived stress scale assessment using item response theory among pregnant women

The current study aimed to assess the psychometric properties of the Spanish language version of the 14-item Perceived Stress Scale (PSS-S) in a population of pregnant women who speak Spanish in Peru using item response theory (IRT). Our study consisted of 5,435 pregnant women who participated in the Pregnancy Outcomes Maternal and Infant Study (PrOMIS) cohort in Peru. Exploratory and confirmatory factor analyses were conducted to determine dimensionality of the scale in this population, and item response theory was conducted to determine the applicability of the PSS. The PSS consisted of a 2-factor questionnaire measuring perceived stress and coping capacity accounting for 77% of variability. The IRT analysis showed differences in item difficulty and discrimination. Item difficulty represents the level of the latent construct where 50% of respondents endorse a particular response, and item discrimination determines the rate of change of the probability of endorsing an item for differing ability levels. For the first factor, perceived stress, item 12 was the least difficult and item 2 was the most difficult. For the second factor, coping capacity, item 9 was the least difficult and item 6 was the most difficult. The Spanish version of the 14-item PSS can be a useful assessment tool for perceived stress, but more IRT should be done to delve further into the psychometric properties of the questionnaire to inform clinicians and policy makers more appropriately.