A longitudinal interaction between pain interference and depression with the burden of headache in individuals with chronic tension type headache (CTTH) was found.

A tension-type headache (TTH) is the third most prevalent pain condition with an estimated prevalence of 42%. In 2010, the general costs for treatment of headache, most related to migraine and TTH, in Europe was €13.8 billion. The Eurolight project estimated that indirect costs accounted for 92% of the financial burden of TTH. It was confirmed from the recent data derived from the Eurolight project that the middle-income European countries such as Lithuania are more substantial for the burden of TTH. Similarly, low-income countries such as Ethiopia are more prone to headache. Therefore, a good knowledge of these parameters associated with the burden of headache can help physicians to understand the vital factors in the management of TTH.

The Eurolight project demonstrated that headache has negative impact on daily life activities such as education, career, and earnings, family, or social life. The term burden includes several factors including physical or emotional burden and according to the literature, headache can affect the physical and emotional aspects of the patients’ life.

Moreover, TTH patients tend to exhibit co-morbid conditions like anxiety, depression or sleep disturbances. Some previous studies conducted on the migraine patients investigated the relationship between depression and the burden of headache. A study conducted by Zebenholzer et al. determined the coexistence of depression and anxiety with TTH and migraine. No study has previously investigated variables associated with the burden of headache in patients with TTH in a longitudinal design. Therefore, in the present study, the author investigated the potential variables associated at one year (longitudinal design) with the physical or emotional component of burden in a cohort of patients with chronic tension-type headache (CTTH).

Rationale behind the research:

No study has previously investigated the variables associated with the burden of headache in patients with TTH in a longitudinal design.

Therefore, the current study investigated the potential variables associated at one year (longitudinal design) with the physical or emotional component of burden in a cohort of patients with CTTH.

Objective:

To investigate variables associated at one year (longitudinal design) with the physical or emotional component of burden in CTTH. 

Study outcome measures:

• Headache diary:

This diary was recorded at baseline and at one-year follow-up. In this, patients registered the frequency of headaches (days per week), the headache intensity on an 11-points numerical pain rate scale (NPRS; 0: no pain, 10: the maximum pain), and the duration of each headache attack (hours per day).

• Burden of headache:

The Headache Disability Inventory (HDI) was used to assess the burden of headache. The HDI was assessed at baseline and at 1-year follow-up.

• Anxiety and depressive symptoms:

The Hospital Anxiety and Depression Scale (HADS) is a 14-items self-report screening scale indicating the presence of anxiety and depressive symptom. It consists of 7 items for evaluating anxiety (HADS-A) and 7 for depression (HADS-D).

• Sleep quality:

The Pittsburgh Sleep Quality Index (PSQI) as used to assess sleep quality. The total score ranges from 0 to 21 where higher score indicates worse sleep quality.

• Health-related quality of life (HQoL):

Quality of life (QoL) was assessed with the Medical Outcomes Study Short Form 36 (SF-36) questionnaire. Total score ranges from 0 (the lowest QoL) to 100 (the highest QoL).

Time period: Baseline and 1 year 

Study Outcomes

• Clinical data of the sample:

Out of 200 individuals with headache, 172 patients (120 women, 50 men, mean age: 48±15 years) with CTTH included in the study. One hundred and thirty (n=130, 76%, 95 women, 35 men, mean age: 47±20 years) were also assessed at one-year follow-up and therefore included in the primary analysis.

• Correlation analysis:

At one year follow up a significant positive correlation was reported between the emotional burden of headache (HDI-E) and headache frequency (r=0.281; P=0.015), sleep quality (r=0.326; P=0.004), and depression (r=0.408; p<0.001). Significant negative correlations between the emotional burden of headache (HDI-E) at 1-year and pain interference (r=−0.508; p<0.001), vitality (r=−0.374; P=0.001) or mental health (r=−0.343; P=0.002) at baseline were also found: the lower the vitality, pain interference or mental health score. Significant positive correlations were observed between the physical burden of headache (HDI-P) at 1-year and headache intensity (r=0.228; P=0.045), frequency (r=0.306; P=0.008) and duration (r=0.376; P=0.009), sleep quality (r=0.291; P=0.01), and depression (r=0.330; P=0.004) at baseline. Finally, significant negative correlations between the physical burden of the headache (HDI-P) at one-year and pain interference (r=−0.556; p<0.001), vitality (r=−0.453; p<0.001) or mental health (r=−0.254; P=0.03) at baseline were also observed.

• Regression analyses:

In this analysis, baseline pain interference (bodily pain) approximately contributed 27.2% (p<0.001), whereas baseline depression (HADS-D) contributed an additional 5% (p<0.001) to the variance of emotional burden of headache (HDI-E) at one-year follow-up. When combined, both variables explained 32.2% of the variance in the emotional burden of headache (r2 adjusted: 0.322, F=11.33, p<0.01).

The baseline emotional burden of headache (HDI-E) contributed 46% (p<0.001), pain interference (bodily pain) an additional 6% (p<0.01) and baseline headache duration an additional 3% (p<0.001) of the variance of physical burden of headache (HDI-P) at one-year. When combined, all variables explained 51.1% of the variance in the physical burden of headache (r2 adjusted: 0.511, F=27.77, p<0.01).

• Mediation effects:

Figure 2 summarizes the standardized effect of the first simple mediation model. First, the total effect from pain interference (bodily pain) on depression (HADS-D) was statistically significant (B=−0.18, p<0.001). Second, the total direct effect from pain interference (bodily pain) on emotional burden of headache (HDI-E) at one-year was significant (B=−0.27, p<0.001). Third, the total direct effect from depression (HADS-D) to the emotional burden of headache (HDI-E) at one-year was significant (B= 0.78, p<0.001). Finally, the total indirect effect of pain interference on the emotional burden of headache (HDI-E) at one-year mediated through baseline depression (HADS-D) was also significant (B=−0.07, P=0.04). To consider statistically significant, the partial effect of mediation at this first model, Zobel test was significant (z=−2.52, P=0.01) with a confidence level not including the value 0 (LLCI: -0.1546, ULCI: -0.0236)

Figure 2: Mediation Analysis of Pain Interference on Physical Burden of Headache at one-year through Depression

• The standardized effect of the second simple mediation model is shown in Figure 3. First, the total effect from pain interference (bodily pain) on the emotional burden of headache (HDI-E) was statistically significant (B=−0.28, p<0.001). Second, the total direct effect from pain interference (bodily pain) on the physical burden of headache (HDI-P) at one-year was also statistically significant (B=−0.19, P=0.04). Third, the total direct effect from the baseline emotional burden of headache (HDI-E) on the physical burden of headache (HDI-P) at one-year was significant (B=0.47, p<0.001). Finally, the total indirect effect from pain interference (bodily pain) on the physical burden of headache at one-year mediated through the baseline emotional burden of headache (HDI-E) was also significant (B=−0.13, P=0.04). Again, to consider the partial effect of mediation statistically significant at the second model, the Zobel test revealed that the model was significant (z=−3.74, P=0.002) with a confidence level not including the value 0 (LLCI: -0.2200; ULCI: -0.0734).

Figure 3: Mediation Analysis of Pain Interference on Physical Burden of Headache at one-year through Emotional Burden of Headache

This study showed two important aspects: 1) pain interference was longitudinally associated with both emotional and physical components of burden and 2) a relevant role of emotional aspects in patients with CTTH). Besides, the duration of the headache attack was also found to be associated with the physical component of burden. In addition, the role of depression on the emotional burden in patients with CTTH was probed. It has been previously observed that depression contributes to chronic pain via supraspinal mechanisms and emotional modulation of pain. These results support this mechanism since depression mediated the effect of pain interference on the emotional burden of headache. Similarly, the role of the emotional factor on the physical burden was mediated by emotional aspects of burden in patients with TTH. Therefore, it is possible that emotional (stressful) factors can trigger more headache attacks causing severe pain interference and therefore the higher self-perceived burden.

Beside the biological mechanisms withstanding in these interactions, the present study also showed clinical implications. As the emotional stress and depression are the most common trigger for pain in TTH patients, the proper management of these factors may help reduce the burden perception. Current findings suggest that management of patients with CTTH should include therapeutic interventions targeted to decrease the emotional burden of headache and to decrease depressive symptoms with the aim to decrease the burden of headache.

In conclusion, this study suggests that emotional factors play a relevant role in the association between pain interference and burden in patients with CTTH.