Table 8. Pre-op demographics for lumbar fusion with Si₃N₄ versus other allogenic bone or abiotic spacers.

Demographic	Si3N4				Meta-data			P value
	n	Total	%		n	Total	%
Gender, female	253	450	56.2		533	910	58.6	0.40
Age, mean ± SD	450	58.2±12.4			999	57.5±10.5		0.27
BMI, mean ± SD	447	30.9±6.1			430	25.8±4.1		<0.01
Smoking, yes	71	450	15.8		116	387	30.0	<0.01