Data Analysis
Number of headaches is presented as mean ± standard error of measurement. A repeated-measures analysis of variance was used to assess changes in number of headaches over the 8-week study. A Fisher post hoc test was employed to identify differences among weeks of the study. Change in headache duration or intensity between baseline and treatment was determined by paired ttest. Statistical significance was fixed at P < .05. Statistical analysis was performed with the StatView computer program (SAS Institute Inc. Cary, NC).
Results
The mean number of headaches per week is presented in Figure 1. A repeated-measures analysis of variance indicated a reliable change over time for number of headaches per week (F7,21 = 3.69, P = .009). Post hoc analysis confirmed that headache frequency was significantly lower during the weeks of massage treatment (weeks 5-8) than during the baseline weeks (weeks 1-4). A reduction in number of headaches per week was noted for all subjects within the first week of massage treatment. Additionally, the mean number of headaches per week was reduced from 6.8 during baseline to 2.0 during the treatment period.
The mean duration of headaches during the baseline period was compared with the mean duration during the treatment period (Figure 2). For the group as a whole, mean headache duration decreased from 8.0 ± 4.3 hours during the baseline period to 4.3 ± 2.3 hours during the treatment phase, and the duration of each headache also decreased for each subject. Because there were only 4 subjects in the study, however, the Pvalue of this measure did not achieve statistical significance (P = .058).
The intensity of the most severe headache that occurred each day was marked on a visual analog scale ranging from 0 to 100 mm (with 100 mm indicating the most severe headache). The mean headache intensities during the baseline period and the treatment period are compared in Figure 3. The effect of massage therapy on headache intensity was subject dependent. Two subjects showed marked improvement, 1 subject showed mild improvement, and 1 subject showed an increase in headache intensity. For the group as a whole, changes between the baseline period (44.2 ± 2.2 mm) and the treatment period (35.8 ± 8.2 mm) were not significant for headache intensity as measured by a visual analog scale (P = .19).
