Comparative sensitivity of stopwatch methodology and conventional pain assessment measures for detecting early response to triptans in migraine: Results of a randomized, open-label pilot study

Background: The standard measure of efficacy used in migraine trials is a 4-point patient-rated headache pain intensity (HPI) scale. However, it has been suggested that using a stopwatch to measure the time to meaningful pain relief can provide a more precise measurement of treatment response. Objective: This study evaluated the sensitivity of a stopwatch method for detecting meaningful relief of headache pain and the correlation of this method with the HPI scale and a 5-point pain relief scale. Methods: In this open-label, parallel-group pilot study, patients were randomized to receive oral eletriptan 40 mg, eletriptan 80 mg, or rizatriptan 10 mg for the treatment of a single acute migraine attack. The effect of study treatment on migraine pain was assessed immediately before dosing and at 0.5, 1, 1.5, 2, 3, and 4 hours after dosing. At each time point, patients recorded the 3 types of pain assessment in a patient diary. HPI was rated using the standard 4-point International Headache Society pain intensity scale (from 0 = no pain to 3 = severe pain). Pain relief was rated on a 5-point pain relief scale (from 4 = no relief to 0 = complete relief). The time to the onset of meaningful pain relief was measured using a stopwatch. At 4 hours after dosing, patients provided a global rating of the overall efficacy of study medication on a 5-point scale (from 0 = poor to 4 = excellent). Results: Seventy-nine patients participated in the trial (78.5% female; mean [SD] age, 37.7 [9.8] years; 58.2% white). The median times to meaningful pain relief measured by stopwatch were 84, 72, and 93 minutes for eletriptan 40 mg, eletriptan 80 mg, and rizatriptan 10 mg, respectively (log-rank P = 0.029, eletriptan 80 mg vs rizatriptan 10 mg). At 90 minutes (approximating the median time to meaningful pain relief on the stopwatch), headache response rates using HPI scoring (mild to no pain) were 65%, 68%, and 52% in the respective treatment groups, with no significant difference between groups. On the pain relief scale, the corresponding mean (SD) scores at 90 minutes were 1.6 (1.2), 1.4 (1.3), and 2.0 (1.4) (P = NS). The pain relief-defined response ( >= 75% pain relief) at 90 minutes did not differ significantly between the 3 treatment groups (62%, 56%, and 48%). Detection of early improvement (0.5 and I hour) was similar with the HPI and pain relief scales. Conclusion: The results of this open-label pilot study suggest the convergent validity of 3 pain-assessment methods in migraine, but indicate that the use of a stopwatch may be a more sensitive method for detecting between-group differences.