Table 3 Multivariable regression models assessing differences in health care utilisation of the comparative patient groups, as measured over a one year follow-up period

Outcome variable	Regression model	IRR^* (95% CI)	p-value
Number of subsequent visits	Negative binomial regression	1.19^† (1.01–1.41)	0.038
Number of referrals	Negative binomial regression	0.97^† (0.71–1.32)	0.845
Number of investigations	Negative binomial regression	1.68^† (1.26–2.24)	>0.001

Note: IRR = incidence rate ratio, CI = confidence interval.
↵* Fatigue symptom patient group designated as the reference group.
↵† IRR adjusted for matched variables (age, age², sex, practice number, provider number and quarter of index visit) and remaining covariates (number of previous and co-occurring chronic morbidities, number of previous and co-occurring psychosocial morbidities and previous care-seeking frequency).