Effects of hospital generic drug substitution on diabetes therapy

Figures & data

Table 1 Patient characteristics, average HbA_1c levels, PDD, and adherence to metformin during the five periods of brand switching

Variable	N(%)	Average HbA1c level					P	PDD of metformin					P	Adherence to metformin					P
		Stage						Stage						Stage
		I	II	III	IV	V		I	II	III	IV	V		I	II	III	IV	V
Sex
Female	160(57%)	7.91	7.91	7.95	8.20	8.21	0.139	0.81	0.81	0.81	0.81	0.79	0.987	0.96	0.93	0.90	0.87	0.83	<0.00l
Male	120 (43%)	7.90	7.74	8.08	8.28	8.50	0.001	0.83	0.83	0.83	0.82	0.80	0.965	0.94	0.91	0.90	0.85	0.82	<0.00l
Age, years
Mean (SD)	59.6(10.6)
<50	56 (20%)	8.09	8.01	8.46	8.58	8.82	0.063	0.83	0.86	0.87	0.9	0.89	0.854	0.91	0.88	0.86	0.79	0.77	<0.00l
50–59	89 (32%)	7.91	7.94	8.16	8.24	8.48	0.085	0.81	0.82	0.8	0.79	0.78	0.976	0.96	0.94	0.91	0.90	0.86	<0.00l
60–69	86(31%)	7.87	7.77	7.74	8.18	8.20	0.094	0.83	0.82	0.82	0.83	0.81	0.985	0.95	0.91	0.90	0.87	0.82	<0.00l
≥70	49(18%)	7.78	7.58	7.64	7.91	7.75	0.736	0.77	0.79	0.79	0.74	0.69	0.537	0.96	0.94	0.90	0.87	0.83	<0.00l
CCI
1	141 (50%)	8.14	7.92	8.00	8.36	8.42	0.032	0.77	0.78	0.78	0.79	0.78	0.989	0.95	0.91	0.89	0.85	0.81	<0.00l
2	113 (40%)	7.73	7.76	8.04	8.12	8.27	0.022	0.86	0.86	0.86	0.86	0.83	0.948	0.94	0.94	0.91	0.88	0.85	<0.00l
≥3	26 (9%)	7.44	7.75	7.82	8.06	8.16	0.313	0.86	0.87	0.83	0.76	0.76	0.669	0.97	0.89	0.91	0.84	0.81	0.009
Total	280(100%)	7.91	7.84	8.00	8.23	8.34	<0.00l	0.82	0.82	0.82	0.82	0.80	0.929	0.95	0.92	0.90	0.86	0.83	0.009

Abbreviations: CCI, Charlson’s comorbidity index; HbA_1c, glycated hemoglobin A_1c; PDD, prescribed daily dose; SD, standard deviation.

Table 2 Regression coefficients obtained using the generalized estimating equations for variables predicting HbA_1c levels, PDD, and adherence

Variable	HbA1c level			PDD of metformin			Adherence to metformin
	β	95% CI	P	β	95% CI	P	β	95% CI	P
Stage
I (reference)
II	−0.16	(−0.31, −0.01)	0.033	0.00	(−0.01, 0.02)	0.602	−0.03	(−0.04, −0.01)	<0.001
III	−0.04	(−0.28, 0.19)	0.725	0.00	(−0.02, 0.03)	0.780	−0.05	(−0.07, −0.03)	<0.001
IV	0.12	(−0.19, 0.42)	0.459	0.00	(−0.03, 0.03)	1.000	−0.08	(−0.11, −0.06)	<0.001
V	0.09	(−0.31, 0.48)	0.672	−0.02	(−0.06, 0.02)	0.332	−0.12	(−0.15, −0.10)	<0.001
Sex
Female (reference)
Male	0.05	(−0.24, 0.34)	0.719	0.00	(−0.08, 0.07)	0.900	−0.01	(−0.03, 0.02)	0.614
Age (years)
<50 (reference)
50–59	−0.18	(−0.61, 0.25)	0.412	−0.07	(−0.17, 0.04)	0.198	0.07	(0.03, 0.11)	0.001
60–69	−0.36	(−0.78, 0.06)	0.092	−0.05	(−0.15, 0.05)	0.362	0.04	(0.00, 0.09)	0.036
≥70	−0.56	(−1.00, −0.12)	0.013	−0.13	(−0.24, −0.02)	0.023	0.05	(0.01, 0.10)	0.015
CCI
1 (reference)
2	−0.23	(−0.53, 0.07)	0.139	0.07	(0.00, 0.15)	0.046	0.02	(0.00, 0.05)	0.062
≥3	−0.30	(−0.73, 0.12)	0.164	0.05	(−0.08, 0.18)	0.472	0.01	(−0.04, 0.06)	0.643
Timea	0.00	(0.00, −0.00)	0.171

Note:

a The number of days from the beginning of the study period to the given HbA_1c test date.

Abbreviations: CCI, Charlson’s comorbidity index; CI, confidence interval; HbA_1c, glycated hemoglobin A_1c; PDD, prescribed daily dose.

Table 3 The prescribed daily dose of the other classes of oral anti-diabetes drugs over the different periods of brand switching

Stage	Acarbose				Glimepiride				Glibenclamide				Gliclazide
	N	Mean	SD	P	N	Mean	SD	P	N	Mean	SD	P	N	Mean	SD	P
I	37	0.56	0.20	0.129	109	2.19	1.08	0.026	71	1.35	0.59	0.966	–	–	–	0.949
II	54	0.47	0.17		118	2.35	1.12		74	1.40	0.55		83	1.22	0.54
III	60	0.49	0.18		125	2.50	1.23		66	1.38	0.54		75	1.20	0.51
IV	67	0.48	0.15		134	2.60	1.20		58	1.39	0.53		76	1.21	0.53
V	76	0.49	0.16		135	2.60	1.17		46	1.33	0.55		81	1.25	0.52
	Repaglinide				Nateglinide				Rosiglitazone				Pioglitazone
	N	Mean	SD	P	N	Mean	SD	P	N	Mean	SD	P	N	Mean	SD	P
I	30	1.14	0.48	0.099	–	–	–	0.617	85	0.90	0.32	0.454	21	1.00	0.00	0.912
II	31	1.35	0.42		3	0.85	0.17		83	0.87	0.31		34	0.94	0.18
III	24	1.29	0.42		7	0.88	0.16		81	0.85	0.32		38	0.94	0.25
IV	17	1.44	0.40		4	0.92	0.17		85	0.85	0.32		48	0.93	0.33
V	13	1.46	0.45		5	0.77	0.22		61	0.81	0.29		59	0.96	0.35

Abbreviation: SD, standard deviation.