. 2021 Dec 11;61(8):3378–3389. doi: 10.1093/rheumatology/keab915

Table 6.

Multivariable PWP gap models for ‘severe flare’

	LLDAS (n = 286)		LA (n = 314)		Toronto-LDA (n = 136)		Remission on-treatment (SLEDAI-defined) (n = 261)		Remission off-treatment (SLEDAI-defined) (n = 134)		Remission on-treatment (BILAG-defined) (n = 182)		Remission off-treatment (BILAG-defined) (n = 90)
	HR (95% CI)	P-value	HR (95% CI)	P-value	HR (95% CI)	P-value	HR (95% CI)	P-value	HR (95% CI)	P-value	HR (95% CI)	P-value	HR (95% CI)	P-value
Multivariate models including ‘target attainment at any time point’^a

	Model 1		Model 2		Model 3		Model 4		Model 5

Disease duration (>1 year)	0.82 (0.77, 0.88)	<0.001	0.82 (0.77, 0.88)	<0.001	0.83 (0.77, 0.89)	<0.001	0.83 (0.77, 0.88)	<0.001	0.83 (0.77, 0.90)	<0.001	NA		NA
Ethnicity^b
Asian	0.85 (0.70, 1.02)	0.081	0.85 (0.71, 1.03)	0.089	0.78 (0.63, 0.95)	0.014	0.84 (0.70, 1.02)	0.071	0.78 (0.63, 0.95)	0.016
White British	0.86 (0.72, 1.02)	0.081	0.86 (0.72, 1.02)	0.084	0.78 (0.65, 0.94)	0.001	0.84 (0.70, 1.00)	0.050	0.79 (0.65, 0.95)	0.013
Target state attainment at any time point	0.15 (0.11, 0.20)	<0.001	0.33 (0.28, 0.39)	<0.001	0.21 (0.15, 0.31)	<0.001	0.19 (0.15, 0.24)	<0.001	0.13 (0.09, 0.20)	<0.001
Increasing SDI score during f/u	1.10 (1.05, 1.14)	<0.001	1.10 (1.06, 1.14)	<0.001	1.10 (1.06, 1.14)	<0.001	1.10 (1.06, 1.14)	<0.001	1.09 (1.04, 1.15)	<0.001

Multivariable PWP gap models with ‘percentage of the cumulative duration of follow-up’ in each target state^c

	Model 6		Model 7		Model 8		Model 9		Model 10		Model 11		Model 12

Disease duration (>1 year)	0.83 (0.78, 0.90)	<0.001	0.84 (0.78, 0.90)	<0.001	0.82 (0.76, 0.89)	<0.001	0.84 (0.79, 0.91)	<0.001	0.84 (0.78, 0.90)	<0.001	0.82 (0.75, 0.88)	<0.001	0.82 (0.76, 0.89)	<0.001
Ethnicity^b
Asian	0.85 (0.70, 1.03)	0.095	0.84 (0.69, 1.02)	0.084	0.76 (0.62, 0.92)	0.006	0.83 (0.68, 1.00)	0.051	0.83 (0.69, 1.01)	0.059	0.76 (0.62, 0.92)	0.006	0.77 (0.63, 0.95)	0.013
White British	0.85 (0.71, 1.01)	0.072	0.84 (0.70, 1.00)	0.056	0.77 (0.64, 0.93)	0.006	0.80 (0.67, 0.96)	0.016	0.82 (0.69, 0.97)	0.022	0.77 (0.64, 0.93)	0.006	0.79 (0.66, 0.95)	0.012
Percentage cumulative duration in each target^c,d	0.97 (0.96, 0.98)	<0.001	0.98 (0.97, 0.99)	<0.001	0.99 (0.98, 1.0)	0.069	0.98 (0.97, 0.99)	<0.001	0.96 (0.95, 0.97)	<0.001	0.99 (0.98, 1.0)	0.124	0.97 (0.95, 0.98)	<0.001
Increasing SDI score during f/u^d	1.09 (1.01, 1.14)	<0.001	1.09 (1.05, 1.14)	<0.001	1.10 (1.05, 1.16)	<0.001	1.09 (1.05, 1.14)	<0.001	1.10 (1.05, 1.14)	<0.001	1.11 (1.05, 1.16)	<0.001	1.10 (1.05, 1.16)	<0.001

Within these models, target achieved at least once.

African/Caribbean ethnicity is the reference variable.

Percentage cumulative duration in target is relative to total follow-up period. HR’s relate to each 1% increase of cumulative time in target. Those with complete data needed for target assessment included, leading to different numbers per PWP-Gap model. ^dTime-varying covariates: percentage cumulative duration in target, increasing SDI-score during follow-up. BILAG: British Isles Lupus assessment group; Cl: confidence interval; f/u: follow-up; HR: hazards ratio; LA: low activity; LDA: low disease activity; LLDAS: lupus low disease activity state; NA: models could not be fitted; PWP: Prentice–Williams–Peterson. BILAG-score used to define severe flare in all models. The HR, 95% CI and p-value are shown in bold text in instances where a co-variate is significant within the multivariate models.