Influence of safety warnings on ESA prescribing among dialysis patients using an interrupted time series

BMC Nephrology

Table 3 Results of interrupted time series model for selected variables

	Change in ESA/week each month prior to black box warning			Change in ESA/week each month post black box warning			Change in ESA/eeek Level after black box warning
	Beta1	SD	p-value	Beta2	SD	p-value	Beta3	SD	p-value
All	-37	25.8	0.162	-41	27.6	0.146	-882	773.9	0.260
Hematocrit value
< 30%	224	84.1	0.010	-137	85.7	0.114	6220	2423.0	0.013
30 - < 36%	46	38.1	0.232	-137	85.7	0.114	6220	2423.0	0.013
≥ 36%	-164	23.0	<.0001	-80	23.0	0.001	-4744	648.2	<.0001
Facility profit status
For-profit	-31	27.7	0.271	-49	30.2	0.109	0.109	835.2	0.440
Non-profit	-90	33.2	0.009	-30	32.7	0.363	-2487	985.4	0.015
Facility chain status ^
Large chains
Chain 1 (FP)	-90	30.0	0.004	-103	31.8	0.002	-2148	870.9	0.017
Chain 2 (FP)	-15	35.4	0.673	-27	37.7	0.480	-61	1060.0	0.954
Chain 3 (NP)	94	44.9	0.041	43	44.6	0.343	3189	1288.0	0.016
Medium chains	72	26.2	0.008	-97	26.5	0.001	1703	752.6	0.028
Small/nonchain	-6	24.8	0.797	-49	24.9	0.055	-432	723.3	0.553

Notes: SD Standard Deviation, FP For-profit, NP Nonprofit.
Variables included in Table 3 were selected based on one or more significant Beta value (p < 0.05).
Model intercept coefficient for all variables in Table 1 is significant (p < 0.0001). Since the time after the FDA warnings is not orthogonal to Beta3, the slope after the warnings (Beta2) is conditioned on the change in level (Beta3).
^ Large chains (Chain 1 - Chain 3) are defined as 100 or more units. Medium chains defined as 10 to ≤ 99 units. Small/Nonchains defined as < 10 units.

ISSN: 1471-2369