Temporal Summation of Pain Is Not Amplified in a Large Proportion of Fibromyalgia Patients

Table 1

Clinical and psychophysical differences between fibromyalgia patients and healthy controls.

Variable	FM; (𝑛=72)	<45°C; (𝑛=37)	>45°C; (𝑛=35)	HC; (𝑛=39)	Statistics; (2 groups)	Statistics; (3 groups)
Age	47.6; (9.8)			44.8; (9.5)	𝐹=2.1; 𝑃=0.147
Menstrual cycle	Yes, 27; no, 45			Yes, 18; no, 18*	𝜒^2=2.7; 𝑃=0.259
Antidepressants		Yes, 12; No, 24*	Yes, 15; No, 20		𝜒^2=0.7; 𝑃=0.409
Anticonvulsants		Yes, 9; No, 25*	Yes, 8; No, 27		𝜒^2=0.1; 𝑃=0.728
FIQ total score		58.1±15.3	56.0±13.3		𝐹=0.4; 𝑃=0.549
FIQ pain item		7.1±2.2	7.0±1.7		𝐹=0.1; 𝑃=0.795
Pain rating at time 0 (%)	50.1±24.2	48.6±25.3	51.7±23.4	50.4±24.7	𝐹=0.003; 𝑃=0.954	𝐹=0.1; 𝑃=0.862
TPTs (°C)	39.9^∘C±3.7	38.6±2.5	41.3±4.1	42.2±3.2	𝐹=10.9; 𝑃=0.001	𝐹=12.1; 𝑃=0.0001**
Experimental temperature (°C)	44.4^∘C±2.3	42.6±1.7	46.2±0.9	46.4^∘C±1.0	𝐹=27.3; 𝑃=0.0001	𝐹=106.6; 𝑃=0.0001**
Temporal summation (Δ)	4.8±25.9	−2.9±25.1	12.9±24.7	14.9±29.0	𝐹=3.5; 𝑃=0.068	𝐹=5.0; 𝑃=0.008**

Δ: delta, FIQ: Fibromyalgia Impact Questionnaire, FM: fibromyalgia, HC: healthy controls, TPTs: thermal pain thresholds, ± refers to standard deviations.
*missing data for a few subjects; **FM lower than 45°C < 2 other groups (Bonferroni correction).