Validating Migraine-specific Quality of Life Questionnaire
Validating Migraine-specific Quality of Life Questionnaire
The current study demonstrates that the MSQ is a reliable and valid measure of the HRQL among adults with CM and can differentiate the impact of headache across the spectrum of headache frequency as defined for EM and CM. Floor effects were observed for the same 5 items among both CM and EM, while ceiling effects were only observed for 1 item among the CM group. Study results also indicated that the MSQ has high internal consistency and reliability among migraine sufferers, with our results being comparable to those of previous validation studies. Consistent with pre-hypothesized relationships between the MSQ scales and other HRQL instruments, convergent and discriminant validity were supported by relatively higher correlations between the MSQ and the HIT-6 and the MIDAS and lower correlations between the MSQ and the PHQ-4. Construct validity was further confirmed within the framework of known-groups validity, with results showing that MSQ scores differed significantly across CM and EM patients and other important headache severity criterion measures.
Unexpectedly, the MSQ scales had low correlations with HDPM. The low correlations may be at least partially explained by the fact that the MSQ is designed to capture the multifaceted construct of migraine impact, which includes not only the frequency but also the intensity and the duration of headaches and the patient's own evaluation of how migraines impact their quality of life. Indeed, other studies have reported disability to be more strongly associated with headache pain severity rather than with headache frequency, which further concurs with our findings. In the MSQ development and validation study, frequency of headaches over the past 12 months had low to moderate correlations with the MSQ scales. In that study, from among the 3 MSQ scales, the EF scale was the most strongly correlated (r = −0.48) with headache frequency, followed by the RR (r = −0.27) and lastly the RP (r = −0.14), a ranking of correlations that was mirrored in our results (for CM and EM combined only).
One limitation of the study was that the migraine diagnosis was not based on physician report but used the participants' self-report to the migraine screening questions. Therefore, it is possible that some respondents were misclassified. Furthermore, electronic data collection conducted in this study design may have introduced participation bias because individuals lacking appropriate computer skills, access, or willingness may not have been included. Finally, given the cross-sectional study design, certain psychometric properties, such as test–retest reliability and responsiveness, could not be assessed.
Despite these limitations, the results of this study provide important new evidence for the psychometric reliability and validity of the MSQ. Although the MSQ has been shown to be a valid tool for measuring functional status and the effect of treatment among general migraine patients, the present study expands the scope of these findings by providing quantitative indicators of the validity of the MSQ specifically among CM adults, a group that has traditionally been understudied in validation analyses of headache- or migraine-specific HRQL measures.
The MSQ has been successfully used to assess the effect of therapy in several randomized clinical trials of migraine treatment, including clinical trials among patients with CM. HRQL instruments are most effective when they can capture clinically meaningful data while minimizing respondent burden without compromising validity. Accordingly, the combination of these key elements makes the MSQ a valuable tool, not only for use in clinical trials, but also for clinicians who manage treatment of CM and EM patients.
The importance of differentiating between headache subtypes in order to optimize treatment is an increasingly relevant issue for clinical practitioners. PRO instruments can be integrated within clinical practice to guide diagnosis and treatment that is targeted to the correct subtype of migraine. The growing interest in using HRQL measures to characterize differences between EM and CM patients supports the need to study the psychometric properties of these tools. Although several studies have examined the validity of the MSQ using samples of EM patients or general migraine patients, this was the first study that examined the validity of the MSQ in capturing distinct domains of migraine impact, across patients with different headache frequency levels.
Longitudinal studies exploring test–retest and responsiveness are recommended in the future to assess the reliability and validity of the MSQ in CM patients. In addition, continued examination of the psychometric properties of HRQL instruments that characterize the impact of migraine in CM and EM patients is needed to expand the current understanding of differences across these 2 groups.
Discussion
The current study demonstrates that the MSQ is a reliable and valid measure of the HRQL among adults with CM and can differentiate the impact of headache across the spectrum of headache frequency as defined for EM and CM. Floor effects were observed for the same 5 items among both CM and EM, while ceiling effects were only observed for 1 item among the CM group. Study results also indicated that the MSQ has high internal consistency and reliability among migraine sufferers, with our results being comparable to those of previous validation studies. Consistent with pre-hypothesized relationships between the MSQ scales and other HRQL instruments, convergent and discriminant validity were supported by relatively higher correlations between the MSQ and the HIT-6 and the MIDAS and lower correlations between the MSQ and the PHQ-4. Construct validity was further confirmed within the framework of known-groups validity, with results showing that MSQ scores differed significantly across CM and EM patients and other important headache severity criterion measures.
Unexpectedly, the MSQ scales had low correlations with HDPM. The low correlations may be at least partially explained by the fact that the MSQ is designed to capture the multifaceted construct of migraine impact, which includes not only the frequency but also the intensity and the duration of headaches and the patient's own evaluation of how migraines impact their quality of life. Indeed, other studies have reported disability to be more strongly associated with headache pain severity rather than with headache frequency, which further concurs with our findings. In the MSQ development and validation study, frequency of headaches over the past 12 months had low to moderate correlations with the MSQ scales. In that study, from among the 3 MSQ scales, the EF scale was the most strongly correlated (r = −0.48) with headache frequency, followed by the RR (r = −0.27) and lastly the RP (r = −0.14), a ranking of correlations that was mirrored in our results (for CM and EM combined only).
One limitation of the study was that the migraine diagnosis was not based on physician report but used the participants' self-report to the migraine screening questions. Therefore, it is possible that some respondents were misclassified. Furthermore, electronic data collection conducted in this study design may have introduced participation bias because individuals lacking appropriate computer skills, access, or willingness may not have been included. Finally, given the cross-sectional study design, certain psychometric properties, such as test–retest reliability and responsiveness, could not be assessed.
Despite these limitations, the results of this study provide important new evidence for the psychometric reliability and validity of the MSQ. Although the MSQ has been shown to be a valid tool for measuring functional status and the effect of treatment among general migraine patients, the present study expands the scope of these findings by providing quantitative indicators of the validity of the MSQ specifically among CM adults, a group that has traditionally been understudied in validation analyses of headache- or migraine-specific HRQL measures.
The MSQ has been successfully used to assess the effect of therapy in several randomized clinical trials of migraine treatment, including clinical trials among patients with CM. HRQL instruments are most effective when they can capture clinically meaningful data while minimizing respondent burden without compromising validity. Accordingly, the combination of these key elements makes the MSQ a valuable tool, not only for use in clinical trials, but also for clinicians who manage treatment of CM and EM patients.
The importance of differentiating between headache subtypes in order to optimize treatment is an increasingly relevant issue for clinical practitioners. PRO instruments can be integrated within clinical practice to guide diagnosis and treatment that is targeted to the correct subtype of migraine. The growing interest in using HRQL measures to characterize differences between EM and CM patients supports the need to study the psychometric properties of these tools. Although several studies have examined the validity of the MSQ using samples of EM patients or general migraine patients, this was the first study that examined the validity of the MSQ in capturing distinct domains of migraine impact, across patients with different headache frequency levels.
Longitudinal studies exploring test–retest and responsiveness are recommended in the future to assess the reliability and validity of the MSQ in CM patients. In addition, continued examination of the psychometric properties of HRQL instruments that characterize the impact of migraine in CM and EM patients is needed to expand the current understanding of differences across these 2 groups.