Table 4. . Negative binomial regression model evaluating the effect of IL1A rs1800587 on acute crisis pain and ordinal logistic regression model on utilization groups.

Model	Acute crisis pain		Utilization
	IRR (95% CI)†	p-value	Estimate (95% CI)‡	p-value
Additive	0.93 (0.70–1.23)	0.606	-0.02 (-0.54–0.51)	0.949
Dominant	0.93 (0.55–1.56)	0.774	0.22 (-0.75–1.20)	0.652
Recessive	0.90 (0.60–1.35)	0.605	-0.18 (-0.94–0.58)	0.637

The major alleles are the reference genotypes in the analyses. Ordered log–odds estimate in which the minor allele would result in a higher utilization group. Regression models are adjusted for age, sex, ethnicity and sickle cell type. Low utilization group (1–3 utilizations), high utilization group (4–38 utilizations).

^†IRR and 95% CI.

^‡Ordered log–odds estimate and 95% CI.

IRR: Incident rate ratio.