Risk Factors and the Usual Source of Care on Non-Adherence to Antihypertensive Drugs in Immigrants with Hypertension

Figures & data

Table 1 Baseline Characteristics of Immigrants and Native-Born Koreans with Hypertension Included in the Study

Variables		Total (n=8228)		Immigrants (n=4114)		Native-Born Koreans (n=4114)		P-value
		N	%	N	%	N	%
Sex	Male	3559	43.25	1777	43.19	1782	43.32	0.9114
	Female	4669	56.75	2337	56.81	2332	56.68
Age	30–49 years	2859	34.75	1425	34.64	1434	34.86	0.9729
	50~64 years	3376	41.03	1683	40.91	1693	41.15
	65–74 years	1417	17.22	715	17.38	702	17.06
	≥75 years	702	8.53	354	8.60	348	8.46
Residential area	City	7602	92.39	3933	95.60	3669	89.18	<0.0001
	Rural area	626	7.61	181	4.40	445	10.82
Type of insurance	National Health Insurance	7814	94.97	3833	93.17	3981	96.77	<0.0001
	Medical Aid	414	5.03	281	6.83	133	3.23
Level of insurance contribution	Low	3108	37.77	1954	47.50	1154	28.05	<0.0001
	Middle	3392	41.23	1791	43.53	1601	38.92
	High	1728	21.00	369	8.97	1359	33.03
Number of household members	1 (self)	2400	29.17	1515	36.83	885	21.51	<0.0001
	≥2	5828	70.83	2599	63.17	3229	78.49
CCI	0	5794	70.42	2916	70.88	2878	69.96	0.3066
	≥ 1	2434	29.58	1198	29.12	1236	30.04
Comorbidities	No	7745	94.13	3958	96.21	3787	92.05	<0.0001
	Yes	483	5.87	156	3.79	327	7.95
Diabetes	No	7858	95.50	3975	96.62	3883	94.39	<0.0001
	Yes	370	4.50	139	3.38	231	5.61
Number of visited clinics	1–2	3448	41.91	1491	36.24	1957	47.57	<0.0001
	3–5	3756	45.65	1979	48.10	1777	43.19
	≥6	1024	12.45	644	15.65	380	9.24
Number of hypertension medications	1	6847	83.22	3381	82.18	3466	84.25	0.0122
	≥2	1381	16.78	733	17.82	648	15.75
Immigration status	Permanent resident	-	-	971	23.60	-	-	-
	Marriage immigrant	-	-	739	17.96	-	-
	Naturalized resident	-	-	2404	58.43	-	-

Abbreviation: CCI, Charlson Comorbidity Index.

Figure 1 Flow diagram of the selection process of study subjects.

Figure 2 Mean MPR according to sex (A), age group (B), and the number of visited clinics (C) between immigrants and native-born Koreans. MPR: medication possession ratio.

Figure 3 Medication adherence patterns for antihypertensive drugs over time between immigrants and native-born Koreans. MPR: medication possession ratio.

Table 2 Comparison of Non-Adherence to Antihypertensive Drugs Between Immigrants and Native-Born Koreans

	Adjusted OR*	95% CI
Immigrants (ref: native-born Koreans)	2.01	1.83–2.21
Subgroup analysis^†
Sex (ref. native-born Koreans)
Men	2.00	1.72–2.31
Women	2.07	1.82–2.35
Age group (ref. native-born Koreans)
30~49 years	2.28	1.92–2.71
50~64 years	2.05	1.78–2.36
65 years and older	1.69	1.37–2.08
Number of visited clinics (ref. native-born Koreans)
1~2	2.04	1.76–2.36
3 and over	2.06	1.82–2.34

Notes: *Age, sex, and CCI were matched between immigrants and native-born Koreans. Therefore, the matched factors were not included in the regression model, which was adjusted for type of insurance, residential region, insurance premium quantiles, number of household members, comorbidities, diabetes mellitus, and number of antihypertension. †Comparison of non-adherence between immigrants and native-born Koreans stratified by sex, age group, and number of visited clinics. The regression model was adjusted for number of visited clinics, type of insurance, residential region, insurance premium quantiles, number of household members, comorbidities, diabetes mellitus, and number of antihypertension. Significant results made in bold type.

Abbreviations: OR, odds ratio; CI, confidence interval; CCI, Charlson Comorbidity Index.

Table 3 Potential Risk Factors Significantly Associated with Non-Adherence to Antihypertensive Drugs in Immigrants by Logistic Regression Analysis

Variables	Category	OR	95% CI
Immigration status	Naturalized citizen	Ref.
	Permanent resident	1.12	0.95	1.32
	Marriage immigrant	1.43	1.19	1.72
Sex	Male	Ref.
	Female	0.91	0.80	1.04
Age group (years)	30–49	Ref.
	50–64	0.66	0.56	0.77
	65 and older	0.59	0.49	0.72
Type of insurance	NHI	Ref.
	Medical Aid	1.39	1.05	1.85
Residential area	Urban area	Ref.
	Rural area	0.88	0.65	1.21
Level of insurance contribution	Low	Ref.
	Middle	1.03	0.89	1.20
	High	0.58	0.45	0.73
Living alone	Yes	Ref.
	No	1.14	0.99	1.31
Number of visited clinics (n)	1–2	Ref.
	3–5	1.31	1.14	1.51
	6 and over	1.58	1.30	1.93
CCI score	0	Ref.
	1 and over	1.36	1.17	1.59
Comorbidity	No	Ref.
	Yes	0.65	0.46	0.91
Diabetes	No	Ref.
	Yes	0.61	0.42	0.88
Number of antihypertensive drugs	1	Ref.
	2 and over	0.65	0.55	0.77

Note: Significant results are shown in bold type.

Abbreviations: OR, odds ratio; NHI, National Health Insurance; CCI, Charlson Comorbidity Index.