Table 2.

Competing-risk model for disease complications and early anti-TNFα comparative effectiveness analysis

	Stricturing behaviour (B2)		Penetrating behaviour (B3)
	HR (95% CI)	p value	HR (95% CI)	p value
Competing-risk model (n=913)
Age at diagnosis	1·07 (0·97–1·17)	0·16	1·45 (1·17–1·80)	0·0008
African American race	1·08 (0·52–2·22)	0·84	3·19 (1·39–7·31)	0·0061
Isolated ileal location (L1)	1·60 (0·88–2·91)	0·12	1·23 (0·51–2·95)	0·64
ASCA IgA positive	1·69 (0·94–3·07)	0·0816	2·68 (1·19–6·04)	0·0171
CBir1 positive	2·30 (1·26–4·20)	0·0070	3·01 (1·31–6·93)	0·0097
Early anti-TNFα comparative effectiveness analysis of propensity-score matched cohort (n=382)
Age at diagnosis	1·13 (0·97–1·31)	0·11	1·37 (1·03–1·81)	0·0278
African American race	1·25 (0·43–3·63)	0·68	3·02 (0·97–9·39)	0·0555
Isolated ileal location (L1)	1·66 (0·65–4·26)	0·29	1·26 (0·36–4·43)	0·72
ASCA IgA positive	2·87 (1·21–6·82)	0·0165	2·09 (0·71–6·12)	0·18
CBir1 positive	1·52 (0·63–3·70)	0·35	4·82 (1·53–15·2)	0·0072
Early anti-TNFα	1·13 (0·51–2·51)	0·76	0·30 (0·10–0·89)	0·0296

In the competing-risk model in the overall cohort (n=913), AUROC was 0·7 (95% CI 0·64–0·76), sensitivity 66% (95% CI 51–82), specificity 63% (95% CI 55–71), positive predictive value 14% (95% CI 12–17), negative predictive value 95% (95% CI 94–97), and prevalence of complications 8·5%. These characteristics were calculated from 1000 random split samples; for each, one half was used to validate predictions based on the other half. The cutoff set to balance sensitivity with specificity was 0·077. By contrast, for the model based on clinical factors alone, AUROC was 0·6 (95% CI 0·56–0·69), sensitivity 56% (95% CI 38–67), specificity 63% (95% CI 56–71), positive predictive value 12% (95% CI 10–15), and negative predictive value 94% (95% CI 92–95). In the early anti-TNFα comparative effectiveness analysis, the propensity of early anti-TNFα therapy use within 3 months of diagnosis in individual patients was analysed, and estimated propensity scores were used to obtain 191 matched pairs, each consisting of one patient who received early anti-TNFα therapy and one patient with similar baseline characteristics who did not. Prevalence of complications was 10·7% (6·8% for B2 and 3·9% for B3).

TNFα=tumour necrosis factor α. HR=hazard ratio. ASCA=anti-Saccharomyces cerevisiae antibodies. AUROC=area under the receiver operator characteristic curve.