Objective: The authors compared the efficacy and acceptability of continuous versus intermittent treatment with a selective serotonin reuptake inhibitor in women with severe premenstrual syndrome and determined the effects of postmenstrual symptom severity and depression history as covariates of the treatment response.

Method: Patients who met symptom criteria and reported impaired functioning after three screening cycles were randomly assigned to three cycles of double-blind, placebo-controlled treatment with continuous (full-cycle dosing) or intermittent (luteal-phase dosing) sertraline. The design was stratified for severity of postmenstrual symptoms and history of major depression. Flexible sertraline dose was 50-100 mg/day. Outcome measures were the Daily Symptom Rating Form score and patient global ratings of functioning.

Results: Both sertraline groups improved significantly more than the placebo group as assessed by total premenstrual Daily Symptom Rating Form scores for 3 treatment months. Daily Symptom Rating Form factors that were significantly more improved in the sertraline groups were mood and physical symptoms. Sertraline improvement occurred swiftly in the first month of treatment. Gradual placebo improvement was similar to sertraline in the third month. Subjects with higher postmenstrual symptoms before treatment remained more symptomatic regardless of the dosing regimen. A history of major depression was not associated with treatment response. More sertraline-treated subjects reported improved functioning in the domains of family relationships, social activities, and sexual activity.

Conclusions: Premenstrual dosing does not differ from continuous dosing with sertraline in premenstrual syndrome treatment. Higher levels of postmenstrual symptoms limit treatment response and are important to define in treatment of premenstrual syndrome.