Chronobiological variables predict non-response to serotonin and noradrenaline reuptake inhibitors in fibromyalgia: a cross-sectional study.

Available data shows associations between chronotype, circadian rhythms, sleep quality and fibromyalgia (FM) presentation. However, no studies have explored links between the chronobiological variables and effectiveness of pharmacotherapy. We aimed to assess the chronotypes, circadian rhythms, sleep-wake cycle and sleep quality in FM and their links to treatment response to serotonin and noradrenalin reuptake inhibitors (SNRI). 60 FM patients: 30 responsive to SNRI (FM T[+]), 30 non-responsive to SNRI (FM T[-]) and 30 healthy controls participated. Subjects were assessed by physician and with questionnaire tools: Composite Scale of Morningness, Biological Rhythms Interview of Assessment in Neuropsychiatry, Sleep-Wake Pattern Assessment Questionnaire, Pittsburgh Sleep Quality Index and Fibromyalgia Impact Questionnaire. ANOVA analysis and simple logistic regressions were used to examine the relationships between chronological variables and response to SNRI. FM T[-] vs. FM T[+] presented lower morning affect (11.50[95%CI 9.96-13.04] vs. 14.00[95%CI 12.42-15.57];p=0.04), anytime wakeability (2.27[95%CI 1.4-3.13] vs. 4.03[95%CI 2.99-5.08];p=0.013) worse overall (11.40[95%CI 9.92-12.88] vs. 7.97[95%CI 6.75-9.19];p=0.002) and subjective (1.70[95%CI 1.30-2.01] vs. 1.17[95%CI 0.94-1.39];p=0.008) sleep quality, higher circadian rhythm disruptions (55.47[95%CI 52.32-58.62] vs. 44.97[95%CI 41.31-48.62];p<0.001), sleep disturbances (1.63[95%CI 1.38-1.68] vs. 1.30[95%CI 1.1-1.5];p=0.04), sleeping-medication use (1.80[95%CI 1.27-2.32] vs. 0.70[95%CI 0.28-1.12];p=0.003). Levels of morningness (AIC=82.91,OR=0.93,p=0.05), morning affect (AIC=81.901,OR=0.86,p=0.03) diurnal dysrhythmia (AIC=69.566,OR=1.14,p<0.001), anytime wakeability (AIC=80.307,OR=0.76,p=0.015), overall sleep quality (AIC=74.665, OR=1.31,p=0.002) subjective sleep quality (AIC=79.353, OR=2.832,p=0.01) and disturbances (AIC=82.669,OR=2.54,p=0.043), sleep medication use (AIC=77.017, OR=1.9,p=0.003) and daytime disfunction (AIC=82.908, OR=1.971,p=0.049) were predictors of non-response to SNRI. Chronobiological variables vary between FM T[+] and FM T[-] and are predictors of non-response to SNRI.