Validation of a Revised Visual Analog Scale for Premenstrual Mood Symptoms: Results from Prospective and Retrospective Trials
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OBJECTIVE: Previous studies have demonstrated that visual analog scales (VASs) are valid and reliable instruments for measuring the severity of premenstrual symptoms. Most of these studies, though, predate the introduction of DSM-IV diagnostic criteria for premenstrual dysphoric disorder (PMDD). Our objective was to assess the reliability and validity of VASs that were revised to better reflect the DSM-IV definition of PMDD. METHODS: Concurrent information from the well-validated Premenstrual Tension Syndrome-Observer (PMTS-O) rating scale was used to evaluate the revised VASs. Data from 4 randomized controlled trials (n = 1208) evaluating the efficacy of paroxetine for the treatment of PMDD were used. Cronbach's alpha coefficient was used to evaluate the internal consistency of the core VAS mood items. Pearson's correlation between scores from the 2 scales was used to assess reliability. RESULTS: The internal consistency among the core VAS mood items (Cronbach's alpha > 0.90 across trials) was high. Luteal VAS scores and corresponding PMTS-O scores were moderately correlated at baseline (P < 0.01). Luteal VAS change scores and corresponding PMTS-O change scores were strongly correlated (P < 0.01). These results did not differ regardless of whether the PMTS-O data were collected prospectively or retrospectively. CONCLUSION: The revised VASs, which approximate the current DSM-IV definition of PMDD, provide a valid and reliable measure of the severity of premenstrual symptoms when evaluated against the validated PMTS-O scale. Our results also suggest that, whether observers assessed severity of PMDD symptoms retrospectively or prospectively using the PMTS-O scale, the correlations with the patient-reported VAS scores were comparable.
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