Medication adherence in patients with diabetes mellitus: does physician drug dispensing enhance quality of care? Evidence from a large health claims database in Switzerland

Figures & data

Figure 1 Distribution of patients’ PDC by dispensing channel.

Abbreviation: PDC, proportion of days covered.

Table 1 Patient characteristics by dispensing channel

Variable	Pharmacy, n=16,292	Physician dispensing, n=10,430	P-value
Sex (female)	7,746 (47.5%)	4,636 (44.4%)	<0.001
Mean age (SD; years)	68.9 (12.1)	69.2 (11.5)	0.297
Age in groups (years)			<0.001
0–44	524 (3.2%)	236 (2.3%)
45–54	1,511 (9.3%)	910 (8.7%)
55–64	3,404 (20.9%)	2,229 (21.4%)
65–74	5,033 (30.9%)	3,348 (32.1%)
75–84	4,498 (27.6%)	2,898 (27.8%)
≥85	1,322 (8.1%)	809 (7.8%)
Managed care plan	4,624 (28.4%)	3,391 (32.5%)	<0.001
High deductible class (>500 Swiss Francs)	864 (5.3%)	575 (5.5%)	0.476
Preceding hospitalization	1,444 (8.9%)	1,105 (10.6%)	<0.001
Number of comorbidities			<0.001
0	1,144 (7.0%)	857 (8.2%)
1	2,732 (16.8%)	2,093 (20.1%)
2	4,172 (25.6%)	2,838 (27.2%)
3	3,076 (18.9%)	1,812 (17.4%)
4	1,982 (12.2%)	1,161 (11.1%)
≥5	3,186 (19.6%)	1,669 (16.0%)
Drug therapy			<0.050
Metformin only	6,824 (41.9%)	4,219 (40.5%)
Metformin and another OAD	5,126 (31.5%)	3,425 (32.8%)
Other combination of OADs	4,342 (26.7%)	2,786 (26.7%)
Mean PDC (SD)	67.9 (27.2)	67.8 (26.5)	0.194
Median PDC (IQR)	72.8 (45.3)	72.5 (43.1)
PDC ≥80%	6,959 (42.7%)	4,355 (41.8%)	0.125

Abbreviations: IQR, interquartile range; OAD, oral antidiabetic drug; PDC, proportion of days covered; SD, standard deviation.

Table 2 Prediction of medication adherence (PDC ≥80%) by patient characteristics

Variable	Adjusted odds ratio*	95% confidence interval	P-value
Sex (female)	0.89	0.85–0.95	<0.001
Age in groups (years)
45–54	1.56	1.27–1.92	<0.001
55–64	1.78	1.47–2.17	<0.001
65–74	1.97	1.63–2.38	<0.001
75–84	1.65	1.36–2.00	<0.001
≥85	1.22	0.99–1.51	0.060
Managed care plan	1.01	0.95–1.07	0.885
High deductible class (>500 Swiss Francs)	0.71	0.63–0.81	<0.001
Preceding hospitalization	0.67	0.61–0.74	<0.001
Dispensing channel (PD)	0.98	0.91–1.06	0.548
Number of comorbidities
1	1.19	1.05–1.35	<0.010
2	1.30	1.15–1.46	<0.001
3	1.43	1.26–1.62	<0.001
4	1.35	1.18–1.54	<0.001
≥5	1.27	1.12–1.44	<0.001
Drug therapy
Metformin and another OAD	9.86	9.21–10.55	<0.001
Other combination of OADs	5.73	5.35–6.14	<0.001

Note:

* Also controlled for cantons (coefficients not shown).

Abbreviations: OAD, oral antidiabetic drug; PD, physician dispensing; PDC, proportion of days covered.

Table S1 Patient characteristics by dispensing channel among patients from the cantons of Lucerne and Aargau

Variable	Pharmacy, n=2,401	Physician dispensing, n=1,001
Sex (female)	1,064 (44.3%)	397 (39.7%)
Mean age (SD; years)	67.8 (11.9)	67.7 (12.0)
Age in groups (years)
0–44	81 (3.4%)	31 (3.1%)
45–54	240 (10.0%)	109 (10.9%)
55–64	574 (23.9%)	245 (24.5%)
65–74	731 (30.4%)	298 (29.8%)
75–84	620 (25.8%)	248 (24.8%)
≥85	155 (6.5%)	70 (7.0%)
Managed care plan	864 (36.0%)	331 (33.1%)
High deductible class (>500 Swiss Francs)	140 (5.8%)	47 (4.7%)
Preceding hospitalization	238 (9.9%)	67 (6.7%)
Number of comorbidities
0	185 (7.7%)	95 (9.5%)
1	477 (19.9%)	208 (20.8%)
2	670 (27.9%)	268 (26.8%)
3	418 (17.4%)	165 (16.5%)
4	281 (11.7%)	113 (11.3%)
≥5	370 (15.4%)	152 (15.2%)
Drug therapy
Metformin only	945 (39.4%)	366 (36.6%)
Metformin and another OAD	785 (32.7%)	353 (35.3%)
Other combination of OADs	671 (27.9%)	282 (28.2%)
Mean PDC (SD)	69.4 (26.5)	68.2 (27.2)
Median PDC (IQR)	74.5 (44.2)	73.6 (43.4)
PDC ≥80%	1,079 (44.9%)	438 (43.8%)

Abbreviations: IQR, interquartile range; OAD, oral antidiabetic drug; PDC, proportion of days covered; SD, standard deviation.

Table S2 Prediction of medication adherence (PDC ≥80%) by patient characteristics among patients from the cantons of Lucerne and Aargau

Variable	Adjusted odds ratio	95% confidence interval	P-value
Sex (male)	1.02	0.87–1.19	0.831
Age in groups (years)
45–54	2.04	1.20–3.45	≤0.010
55–64	2.61	1.59–4.28	≤0.001
65–74	2.53	1.55–4.14	≤0.001
75–84	2.09	1.27–3.43	≤0.010
≥85	1.87	1.07–3.26	≤0.050
Managed care plan	0.97	0.83–1.14	0.697
High deductible class (>500 Swiss Francs)	0.62	0.44–0.88	≤0.010
Preceding hospitalization	0.84	0.64–1.10	0.211
Dispensing channel (PD)	0.88	0.74–1.04	0.122
Number of comorbidities
1	1.20	0.87–1.66	0.263
2	1.38	1.01–1.88	≤0.050
3	1.34	0.96–1.87	0.088
4	1.09	0.76–1.56	0.643
≥5	1.02	0.72–1.45	0.900
Drug therapy
Metformin and another OAD	8.93	7.40–10.77	≤0.001
Other combination of OADs	4.99	4.12–6.04	≤0.001

Abbreviations: OAD, oral antidiabetic drug; PD, physician dispensing; PDC, proportion of days covered.