Table 4.

Participant demographics in the UK biobank.

	Females (n = 1569)	Males (n = 792)	P-value
Age in years, mean (S.E.)	58 (7)	59 (8)	0.266
Treatment			<0.0001
Group 1*	1165	472
Group 2*	378	314
Group 3	26	12
Number of pain sites			0.478
0	174	74
1	265	143
2	278	129
3	287	151
4	179	99
5	104	51
6	43	13
7	6	3
8	222	129

Treatment Group 1 - amitriptyline or nortriptyline; Treatment Group 2 - morphine or fentanyl; Treatment Group 3 – combination of amitriptyline or nortriptyline along with morphine or fentanyl.

^*Significant difference between females and males (P < 0.05). A two-sample t-test was used to assess differences between continues variables and a chi-square test was used to compare counts.