Table 3. Sequential multiple regressions with the SF-12 PCS, SF-12 MCS, and the IBS-QOL as dependent variables.

	SF-12 PCS		SF-12 MCS		IBS-QOL
	s.e.	β	s.e.	β	s.e.	β
Step 1
Age	0.04	−0.14	0.05	0.06	0.09	0.12
Gender	1.47	−0.11	1.75	0.04	3.00	−0.03
Married	1.38	−0.09	1.65	0.06	2.82	−0.12
Education	1.45	−0.03	1.73	0.09	3.43	−0.22
Income	0.01	0.25	0.01	0.08	0.01	0.08
	Model: R2=0.137; ΔR2=0.137		Model: R2=0.043; ΔR2=0.043		Model: R2=0.099; ΔR2=0.099
Step 2
Age	0.04	−0.20	0.05	0.03	0.09	0.11
Gender	1.39	−0.12	1.40	0.01	2.67	−0.07
Married	1.31	−0.07	1.32	0.07	2.51	−0.10
Education	1.34	−0.08	1.35	0.07	4.18	0.09
Income	0.01	0.21	0.01	−0.02	0.01	−0.03
IBS Sx duration	0.05	0.04	0.05	−0.03	0.05	−0.05
IBS Subtype	1.96	0.07	2.99	−0.07	5.86	0.04
IBS Sx severity	0.15	−0.27	0.15	−0.01	0.29	−0.16
Neuroticism	0.13	0.03	0.13	−0.46	0.26	−0.27
Global distress	0.07	−0.26	0.07	−0.24	0.14	−0.24
	Model: R2=0.277; ΔR2=0.140		Model: R2=0.441; ΔR2=0.398		Model: R2=0.343; ΔR2=0.244
Step 3
Age	0.05	−0.20	0.05	0.03	0.08	0.10
Gender	1.36	−0.11	1.41	0.01	2.37	0.04
Married	1.28	−0.05	1.33	0.07	2.24	0.06
Education	1.32	−0.07	1.37	0.06	2.30	0.06
Income	0.01	0.21	0.01	−0.02	0.01	−0.03
IBS sx duration	0.05	0.02	0.05	−0.03	0.08	−0.09
IBS subtype	2.91	−0.15	3.02	−0.08	5.20	0.09
IBS sx severity	0.15	−0.24	0.16	0.01	0.26	−0.10
Neuroticism	0.14	0.11	0.14	−0.45	0.24	−0.11
Global distress	0.07	−0.23	0.07	−0.24	0.12	−0.19
Fear of GI sx	0.05	−0.22	0.05	−0.02	0.08	−0.45
	Model: R2=0.312; ΔR2=0.035		Model: R2=0.441; ΔR2=0.000		Model: R2=0.487; ΔR2=0.144

GI, gastrointestinal; IBS, irritable bowel syndrome; IBS-QOL, IBS-Quality of Life Instrument; SF-12 PCS, SF-12 Physical Component Summary; SF-12 MCS, SF-12 Mental Component Summary.

Note: Numerical values that are bolded are significant at P <0.01.