Impaired Functioning and Quality of Life in Severe Migraine: The Role of Catastrophizing and Associated Symptoms

Participants were 232 frequent migraine sufferers (79% female; average age 38 years; 84% White; average migraine days/month 8.5; average years of problem headaches 15). Participants were recruited from the general population in Columbus, Ohio and surrounding suburban areas and in rural southern Ohio and western West Virginia and were evaluated at sites in Columbus or Athens, Ohio. The study was approved by the Ohio University Institutional Review Board and informed consent was obtained from all subjects. Inclusion criteria were: age 18–65 years; International Headache Society (IHS) diagnosis by a study neurologist of migraine headache with or without aura (24–27); and electronic diary confirmation of at least three migraine episodes within a 30-day period that were associated with impaired functioning. Exclusion criteria included: IHS diagnosis of medication overuse headache or frequent tension-type headache (24–27); current use of prophylactic medication for migraine or tension-type headache; >20 headache days per month; and primary pain disorder (e.g. fibromyalgia, arthritis) other than migraine.

During their initial visit, participants were evaluated and diagnosed by the study neurologists, provided demographic information and completed computer-administered self-report measures of anxiety, depression and catastrophizing in response to headaches. In addition, the Primary Care Evaluation for Mental Disorders (PRIME-MD (28)) interview was completed and participants were instructed how to use the handheld electronic diary to complete headache recordings.

During the following 5 weeks, participants treated their migraines with acute therapy that included triptan, antinausea, and analgesic medications, and recorded migraine characteristics and migraine-related impairment using a daily (Palm OS) electronic diary. At the conclusion of the 5-week period, participants returned to the study site to turn in their electronic diaries (from which one of the five Fn/QoL measures was derived) and to complete questionnaires. At this visit, Fn/QoL over the previous 5-week period was assessed with four self-report computer-administered measures.

The following measures were examined as determinants of Fn/QoL and assessed at visit 1.

The following migraine characteristics were obtained from the electronic diary (33): (i) migraines (number of migraine episodes separated by a 24-h pain-free period); (ii) migraine days (number of recorded days of migraine); (iii) migraine severity [migraine days × average severity, which ranged from 1 (mild) to 3 (severe)]; and (iv), severity of associated symptoms [SAS; sum of the three severity ratings (ranging from 0 = none to 3 = severe) provided for nausea, photophobia and phonophobia for each migraine, summed across all migraines]. To examine the impact of migraine characteristics over a 30-day period, values were normalized for 30 days.

Migraine-related impairments in Fn/QoL were assessed with the following four self-report measures at visit 2.

During the 5-week observation period of this study, participants completed daily recordings of their headache activity using an electronic palm diary. These ratings included impact of migraine on daily functioning (missed and impaired hours of paid and unpaid work, as well as social/recreational activities, and missed sleep). Disability equivalent hours (DE hours) was calculated as [total number of hours missed + 0.5(hours impaired at least 50%)] (41). Mean DE hours in this sample was 31.1 per 30 days (SD = 27.9).

Participants in this study reported an average of 8.5 migraine days (SD = 3.6) and 5.5 migraine episodes (SD = 1.9) per 30 days and, although treated, of moderate severity (Mean = 1.9, SD = 0.4). The migraine severity score averaged 10.6 (SD = 4); severity of associated symptoms mean score was 20.6 (SD = 14.2).

Relatively few of the predictor variables were intercorrelated (Table 1); for the most part variables with significant correlations measured different aspects of the same construct (i.e. migraine characteristics or affective distress). However, catastrophizing and affective variables were modestly correlated (e.g. r = 0.40, P < 0.001 for PCS and BDI). Age and gender were negatively correlated, indicating that women in the study tended to be younger than male participants (mean age for women was 37; for men 42.5). Gender was also associated with severity of associated symptoms, indicating that women in this sample reported greater severity of symptoms than did men.

As would be expected, the five measures of Fn/QoL were correlated (Table 2). Although all five measures were significantly correlated, only the MSQL and the HDI shared more than 50% variance (r = 0.72). This probably reflects the differing item content of measures as well as their imperfect reliabilities.

Two variables exhibited strong first-order correlations (all P < 0.001) with all five measures of Fn/QoL: catastrophizing and severity of associated symptoms (Table 3). Migraine severity also exhibited significant, although smaller, associations with the Fn/QoL measures. The BAI, BDI and PRIME-MD diagnoses were consistently related to impairment in Fn/QoL on measures that assessed the affective distress and worry about headache occurrence that migraines can engender (MSQ, HDI, MOS), but were unrelated, or less strongly related, to measures that assessed only impaired physical functioning (MIDAS or DE hours). Age and gender were unrelated to the Fn/QoL measures.

Multiple regression analyses were used to examine the independent effects of catastrophizing, migraine characteristics and affective distress on measures of migraine-related impairments in functioning and quality of life. In most cases, the migraine characteristics with the highest and most consistent first-order correlations across the five Fn/QoL variables (migraine days, severity of associated symptoms, migraine severity, catastrophizing, anxiety, depression, mood/anxiety diagnosis) were chosen as candidate predictor variables. However, because migraine days shared substantial variance with migraine severity and is actually a constituent element of this calculated variable (migraine severity = migraine days × average severity), it was excluded from the regression analyses to avoid multicollinearity. By including both migraine severity and severity of associated symptoms in the analyses, information is provided about the relative predictive ability of an overall migraine severity rating compared with the more specific severity of associated symptoms. Similarly, because a measure of self-reported depression symptoms (BDI) was highly correlated with both mood/anxiety diagnosis and self-reported anxiety symptoms (BAI), the BDI was excluded to avoid multicollinearity. A backward entry (P > 0.10 to remove) linear regression analysis was calculated for each of the five Fn/QoL measures. Seven variables (age, gender, severity of associated symptoms, migraine severity, BAI score, PCS score and PRIME-MD diagnosis) were entered for each equation.

Catastrophizing and severity of associated symptoms emerged as strong and consistent determinants of Fn/QoL across the five measures (Table 4). The remaining variables accounted for significant unique variance in, at most, two equations. (Our analysis statistically controlled both anxiety disorder diagnosis and BAI anxiety scores. To examine further the role of catastrophizing vs. anxiety, the analyses were rerun in the subset of participants with no anxiety disorder diagnosis (N = 198). The results for catastrophizing were unchanged.)

In this study, catastrophizing emerged as a robust predictor of Fn/QoL in migraine. The association between catastrophizing and Fn/QoL remained strong even after the effects of other variables (e.g. depression, anxiety, migraine characteristics) known to influence Fn/QoL in migraine were controlled. Further, catastrophizing predicted impairments in Fn/QoL across five diverse measures of functioning or quality of life, including measures that assessed impact of headaches on both role and emotional functioning (HDI, MSQL), a daily diary and a self-report measure of migraine-related impairments in daily activities (DE hours, MIDAS), and a global measure of physical, role, and affective functioning (MOS). Despite differences in the item content of measures, catastrophizing was strongly related to impairments in Fn/QoL as assessed by each measure, emerging as an important component of quality of life in migraine.

Our findings also provide additional evidence that the effects of catastrophizing and comorbid depression on Fn/QoL can be distinguished. Consistent with previous findings, affective distress (e.g. reports of anxiety and depression symptoms, or mood/anxiety disorder diagnosis) was associated with impaired Fn/QoL (17, 42). However, across all five Fn/QoL measures, catastrophizing proved an independent and stronger predictor of impaired Fn/QoL than affective variables, indicating that the deleterious effects of catastrophizing and of affective distress on quality of life can be distinguished.

Although unexamined in migraine, catastrophizing is a focus of study in other chronic pain disorders, and the chronic pain literature may provide insights into the role of catastrophizing in chronic headache disorders. Catastrophizing has been associated with elevated pain ratings (9, 43–46), reduced pain tolerance (47), increased pain behaviours (verbal and non-verbal communication of pain) (50) and psychological symptoms (9, 44–46, 49), as well as with greater disability, irrespective of whether disability is assessed by self-report (43, 46, 50, 51) or clinical evaluation (52) across multiple chronic pain disorders. Across chronic pain conditions, and in both laboratory (15) and clinical studies (7, 48, 50, 51) it has been found that catastrophizing can be distinguished from affective distress. These findings, and the strong relationship between catastrophizing and migraine-related impairments in functioning and quality of life observed here, suggests that, at least for some individuals with migraine, catastrophizing plays an important role in migraine-related impairments in Fn/QoL.

The chronic pain literature also raises the possibility that catastrophizing is a risk factor for the progression from episodic to chronic headaches (43, 53). For example, in the Dutch Musculoskeletal Complaint and Consequences study (43), a population-based longitudinal study, catastrophizing emerged as an important risk factor, both for the development of new back pain with disability and for the persistence or worsening of pre-existing back pain. Thus, high levels of catastrophizing predicted the development of new back pain with disability at a 6-month follow-up in individuals who were pain free at baseline [odds ratio (OR) 3.1, 95% confidence interval (CI) 1.1, 8.7] and also predicted back pain with disability in individuals with back pain at baseline (OR 3.0, 95% CI 1.7, 5.4), even when baseline pain severity and disability were controlled (OR 1.5, 95% CI 0.7, 2.9). Although similar findings are unavailable for headache, functional magnetic resonance imaging data raise the possibility that, even in individuals with no pain disorder, catastrophizing is associated with diminished activity in prefrontal cortical circuits involved in pain modulation (54). Preliminary evaluation of catastrophizing as a potential risk factor for headache progression seems warranted.

Catastrophizing, with its helpless and pessimistic thinking and associated pain behaviours (55), may also undermine development of the collaborative physician–patient relationship essential to the management of recurrent headache disorders. The 13-item Pain Catastrophizing Scale may be helpful in identifying this psychological response to headaches. The catastrophizing patient may respond best to empathetic statements that acknowledge the patient's feelings of helplessness and affective distress, while also highlighting the ways the patient can play an active role in management of their headaches. In addition, behavioural interventions have been shown to reduce catastrophizing in chronic pain disorders (7, 56–58), and, in individuals with frequent migraines, behavioural migraine management appears more effective in reducing catastrophizing than (acute or preventive) medication (K.A.H., unpublished data).

Severity of associated symptoms also emerged as an important contributor to migraine-related impairments in Fn/QoL. Even controlling for migraine severity, the severity of associated symptoms predicted impairments in Fn/QoL across all five Fn/QoL measures. Although migraine frequency and severity of headache pain have been associated with impairments in Fn/QoL in a number of studies (3, 17, 19, 20, 59, 60), little information is available about the impact of migraine-associated symptoms (nausea, vomiting, photophobia, phonophobia) on Fn/QoL. The limited available data indicate patient ratings of pain intensity and severity of associated symptoms are highly correlated (61), but one small study with adolescents (N = 37) found that severity of nausea explained impairments in Fn/QoL (23) that were not explained by headache intensity alone. Our findings in a large sample of adults confirm that migraine-associated symptoms and migraine severity are independently associated with migraine-related deficits in Fn/QoL.

A number of instruments that often differ in assessment method, item content and psychometric properties are available to assess the impact of migraine on functioning or, more broadly, quality of life (62). Although we found catastrophizing and severity of associated symptoms independently associated with decrements in Fn/QoL across all five measures examined, differences in sensitivity of Fn/QoL measures were also evident. Self-report and diary measures that primarily assess the impact of migraine on functioning (e.g. hours or days of impairment), such as the MIDAS and electronic diary recordings of DE hours, were relatively insensitive to the impact of psychiatric comorbidity on functioning in this patient sample (see Table 3).

Strengths of this study include the use of electronic daily diary recordings of migraine activity and associated symptoms, the inclusion of structured interviews for psychiatric diagnosis, and the use of multiple Fn/QoL measures. Limitations include a subject sample with frequent disabling episodic migraines that may limit the generalization of results to less frequent or more frequent (chronic) migraine, and the correlational nature of the data which limits causal inferences. Our findings require replication in frequent migraine and other patient and population samples to determine reliability and generalizability.

Catastrophizing and associated symptoms, two variables whose impact on migraine has received limited or no attention in the literature, proved to be consistently associated with migraine-related impairments in Fn/QoL. Recognizing the roles of psychological responses to migraine and the multiple symptoms that may precede, accompany and follow migraine episodes has the potential to improve our understanding of the impact of migraine on peoples' lives and possibly to improve treatment and reduce headache progression.