Pain Catastrophizing in Women With Migraine and Obesity
The Pain Catastrophizing Scale (PCS) was used to assess catastrophic thinking related to pain. This measure asks participants to recall past pain experiences and to indicate the extent to which they experienced each of 13 thoughts or feelings when experiencing pain, on 5-point scales ranging from (0) not at all to (4) all the time. The PCS produces a total score (range: 0–52) and three subscale scores assessing rumination (eg, "I can't seem to get it out of my mind"), magnification (eg, "It's awful and I feel that it overwhelms me"), and helplessness ("There's nothing I can do to reduce the intensity of the pain"). A total score of 30 is the validated cut score for clinically significant levels of catastrophizing. The PCS has demonstrated good reliability and construct validity and has previously been used to assess pain catastrophizing in samples with migraine. Reliability in the present sample was high (Cronbach's alpha = 0.891).
Daily Migraine Activity Monitoring.—Participants reported their migraine activity at the end of each day for 28 consecutive days using a smartphone configured with a Web-based headache diary application. Participants' ratings of migraine attack occurrence (yes/no), maximum headache pain severity (0 [no pain] to 10 [pain as bad as you can imagine]), and duration (hours) were automatically transmitted to the research team, who checked the data and followed up with participants in the event that any responses were missing or unclear. By using an electronic diary, participants' migraine headache activity was time stamped and recorded each day and in real time. This maximized compliance with the assessment protocol and decreased the potential for bias associated with traditional means of data collection such as paper-and-pencil diaries, which are often completed retrospectively. Participant data were summarized as monthly migraine attack frequency, average maximum pain severity, and total monthly attack duration.
Headache Impact.—The six-item Headache Impact Test (HIT-6) is a validated self-administered questionnaire that measures headache impact on "usual daily activities" including work, school, or social activities; pain severity; fatigue and desire to lie down; frustration; and difficulty with concentration. Higher HIT-6 scores indicate greater impact on normal everyday life and ability to function, with scores ≤49, 50–55, 56–59, and ≥60, indicating little to no impact, some impact, substantial impact, and very severe impact, respectively. The HIT-6 is shown to discriminate between different levels of migraine severity and to have good internal and temporal consistency.
Cutaneous Allodynia.—The 12-item Allodynia Symptom Checklist (ASC-12) is a validated self-administered questionnaire designed to measure presence and severity of cutaneous allodynia symptoms during migraine attacks. Scores of 0–2, 3–5, 6–8, and ≥9 indicate none, mild, moderate, and severe allodynia, respectively. Previous research has shown that higher scores on the ASC-12 are associated with higher migraine attack frequency and BMI in individuals with migraine.
Headache Management Self-efficacy.—The Headache Management Self-Efficacy Scale (HMSE) is a self-administered questionnaire containing 25 items that assess the level of confidence in the ability to manage headache pain and prevent headache episodes. Higher HMSE scores are associated with greater use of positive psychological coping strategies to prevent and to manage headaches. The HMSE has high internal consistency and construct validity as evidenced by negative associations with measures of headache severity and disability.
Depression.—The Center for Epidemiologic Studies Depression Scale (CES-D) assesses frequency of depressive mood and symptoms during the past week. Higher CES-D scores indicate greater symptomotology, and a cut-off score of ≥16 indicates clinically significant symptoms of depression. The CES-D has excellent internal consistency, test–retest reliability, and correlated well with other depression measures.
Anxiety.—The seven-item Generalized Anxiety Disorder Scale (GAD-7) assesses severity of anxiety symptoms over the past 2 weeks. Higher GAD-7 scores indicate greater anxiety symptomology with scores of 5, 10, and 15 taken as thresholds for mild, moderate, and severe anxiety, respectively. The GAD-7 is shown to be a reliable and valid measure of anxiety in primary care settings and the general population, and has previously been used in studies involving migraine patients with obesity.
Anthropometric Characteristics.—Height was measured in millimeters using a wall-mounted Harpenden stadiometer (Holtain Ltd., Crosswell, Crymyh, Pembs, UK). Weight was measured in light street clothing, without shoes, and to the nearest 0.1 kg using a calibrated digital scale (Tanita BWB 800; Tanita Corportation of America, Inc., Arlington Heights, IL, USA). BMI was calculated from these measures using the formula: BMI (kg/m) = weight (kg)/(height [m]).
Demographic Characteristics.—Age, race, ethnicity, and level of education were assessed via questionnaire.
Descriptive statistics (mean and standard deviation) were calculated for all continuous variables. Categorical variables were represented using counts and proportions (%). T-test and chi-square were used to compare demographic, anthropometric, migraine, and psychological characteristics between participants with and without clinical levels of pain catastrophizing. Bivariate logistic regression was used to compare the odds of having chronic migraine in participants with and without clinical levels of catastrophizing. Linear regression models were initially conducted to examine PCS total scores, BMI, and their interaction as predictors of migraine characteristics (ie, number of migraine attacks and days; total attack duration; and average maximum pain severity, headache impact [HIT-6 scores], cutaneous allodynia [ASC-12 scores], and headache management self-efficacy [HMSE scores]) in all participants. Given that the models, including the interaction term, were a uniformly poor fit as evidenced by nonsignificant interaction terms and nonsignificant improvements in the model fit, we report the regression models with only PCS total score and BMI as predictors. All analyses were performed using SPSS statistics for Windows (version 20.0; IBM Corp, Armonk NY, USA). Given that this study involved exploratory analysis intended to be hypothesis generating, tolerance for Type I error was set at α < 0.05 for all analyses. This was a secondary analysis of baseline data collected as part of an ongoing randomized controlled trial. For the randomized controlled trial, a sample size of 140 was selected to provide adequate power to compare changes in monthly migraine frequency across behavioral weight loss intervention and migraine education control arms.
Measures
Pain Catastrophizing
The Pain Catastrophizing Scale (PCS) was used to assess catastrophic thinking related to pain. This measure asks participants to recall past pain experiences and to indicate the extent to which they experienced each of 13 thoughts or feelings when experiencing pain, on 5-point scales ranging from (0) not at all to (4) all the time. The PCS produces a total score (range: 0–52) and three subscale scores assessing rumination (eg, "I can't seem to get it out of my mind"), magnification (eg, "It's awful and I feel that it overwhelms me"), and helplessness ("There's nothing I can do to reduce the intensity of the pain"). A total score of 30 is the validated cut score for clinically significant levels of catastrophizing. The PCS has demonstrated good reliability and construct validity and has previously been used to assess pain catastrophizing in samples with migraine. Reliability in the present sample was high (Cronbach's alpha = 0.891).
Migraine Characteristics
Daily Migraine Activity Monitoring.—Participants reported their migraine activity at the end of each day for 28 consecutive days using a smartphone configured with a Web-based headache diary application. Participants' ratings of migraine attack occurrence (yes/no), maximum headache pain severity (0 [no pain] to 10 [pain as bad as you can imagine]), and duration (hours) were automatically transmitted to the research team, who checked the data and followed up with participants in the event that any responses were missing or unclear. By using an electronic diary, participants' migraine headache activity was time stamped and recorded each day and in real time. This maximized compliance with the assessment protocol and decreased the potential for bias associated with traditional means of data collection such as paper-and-pencil diaries, which are often completed retrospectively. Participant data were summarized as monthly migraine attack frequency, average maximum pain severity, and total monthly attack duration.
Headache Impact.—The six-item Headache Impact Test (HIT-6) is a validated self-administered questionnaire that measures headache impact on "usual daily activities" including work, school, or social activities; pain severity; fatigue and desire to lie down; frustration; and difficulty with concentration. Higher HIT-6 scores indicate greater impact on normal everyday life and ability to function, with scores ≤49, 50–55, 56–59, and ≥60, indicating little to no impact, some impact, substantial impact, and very severe impact, respectively. The HIT-6 is shown to discriminate between different levels of migraine severity and to have good internal and temporal consistency.
Cutaneous Allodynia.—The 12-item Allodynia Symptom Checklist (ASC-12) is a validated self-administered questionnaire designed to measure presence and severity of cutaneous allodynia symptoms during migraine attacks. Scores of 0–2, 3–5, 6–8, and ≥9 indicate none, mild, moderate, and severe allodynia, respectively. Previous research has shown that higher scores on the ASC-12 are associated with higher migraine attack frequency and BMI in individuals with migraine.
Headache Management Self-efficacy.—The Headache Management Self-Efficacy Scale (HMSE) is a self-administered questionnaire containing 25 items that assess the level of confidence in the ability to manage headache pain and prevent headache episodes. Higher HMSE scores are associated with greater use of positive psychological coping strategies to prevent and to manage headaches. The HMSE has high internal consistency and construct validity as evidenced by negative associations with measures of headache severity and disability.
Psychological Characteristics
Depression.—The Center for Epidemiologic Studies Depression Scale (CES-D) assesses frequency of depressive mood and symptoms during the past week. Higher CES-D scores indicate greater symptomotology, and a cut-off score of ≥16 indicates clinically significant symptoms of depression. The CES-D has excellent internal consistency, test–retest reliability, and correlated well with other depression measures.
Anxiety.—The seven-item Generalized Anxiety Disorder Scale (GAD-7) assesses severity of anxiety symptoms over the past 2 weeks. Higher GAD-7 scores indicate greater anxiety symptomology with scores of 5, 10, and 15 taken as thresholds for mild, moderate, and severe anxiety, respectively. The GAD-7 is shown to be a reliable and valid measure of anxiety in primary care settings and the general population, and has previously been used in studies involving migraine patients with obesity.
Anthropometric Characteristics.—Height was measured in millimeters using a wall-mounted Harpenden stadiometer (Holtain Ltd., Crosswell, Crymyh, Pembs, UK). Weight was measured in light street clothing, without shoes, and to the nearest 0.1 kg using a calibrated digital scale (Tanita BWB 800; Tanita Corportation of America, Inc., Arlington Heights, IL, USA). BMI was calculated from these measures using the formula: BMI (kg/m) = weight (kg)/(height [m]).
Demographic Characteristics.—Age, race, ethnicity, and level of education were assessed via questionnaire.
Statistical Analysis
Descriptive statistics (mean and standard deviation) were calculated for all continuous variables. Categorical variables were represented using counts and proportions (%). T-test and chi-square were used to compare demographic, anthropometric, migraine, and psychological characteristics between participants with and without clinical levels of pain catastrophizing. Bivariate logistic regression was used to compare the odds of having chronic migraine in participants with and without clinical levels of catastrophizing. Linear regression models were initially conducted to examine PCS total scores, BMI, and their interaction as predictors of migraine characteristics (ie, number of migraine attacks and days; total attack duration; and average maximum pain severity, headache impact [HIT-6 scores], cutaneous allodynia [ASC-12 scores], and headache management self-efficacy [HMSE scores]) in all participants. Given that the models, including the interaction term, were a uniformly poor fit as evidenced by nonsignificant interaction terms and nonsignificant improvements in the model fit, we report the regression models with only PCS total score and BMI as predictors. All analyses were performed using SPSS statistics for Windows (version 20.0; IBM Corp, Armonk NY, USA). Given that this study involved exploratory analysis intended to be hypothesis generating, tolerance for Type I error was set at α < 0.05 for all analyses. This was a secondary analysis of baseline data collected as part of an ongoing randomized controlled trial. For the randomized controlled trial, a sample size of 140 was selected to provide adequate power to compare changes in monthly migraine frequency across behavioral weight loss intervention and migraine education control arms.