Exploring the relationship between coronary heart disease and type 2 diabetes: a cross-sectional study of secondary prevention among diabetes patients

Bjørn Gjelsvik; Anh Thi Tran; Tore J Berg; Åsne Bakke; Ibrahimu Mdala; Kjersti Nøkleby; John G Cooper; Tor Claudi; Karianne Fjeld Løvaas; Geir Thue; Sverre Sandberg; Anne K Jenum

doi:10.3399/bjgpopen18X101636

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Figure 1. Adjusted prevalence of CHD, atrial fibrillation, and stroke by sex and ethnic group. Numbers for sex are adjusted for age and clustering within practices. Numbers for ethnic group are adjusted for age, sex, and clustering (see Table 1).
CHD = coronary heart disease.
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Figure 2. Proportions of patients where CHD was diagnosed ≥1 year previously, the same year, and ≥1 year after the diagnosis of type 2 diabetes (overall and in different ethnic groups)
CHD = coronary heart disease. DM = diabetes mellitus.

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Table 1. Prevalence of coronary heart disease (angina, cardiac infarction, or PCI/bypass), stroke, and atrial fibrillation in patients with type 2 diabetes, stratified by sex, ethnic group, and county (results from the ROSA 4 study, 2014)

	Total^a	Sex^b		Ethnicity^c,d			County^e
		Females	Males	Norwegian	South Asian	Other	Nordland	Hordaland	Rogaland	Akershus	Oslo
CHD
n (prevalence,%)	2260 (22.1)	727 (15.8)	1533 (27.3)	1891 (23.0)	161 (20.2)	108 (17.2)	675 (24.2)	390 (24.3)	386 (20.4)	279 (19.7)	530 (21)
Adjusted prevalence (95% CI)^a	22.1(21.2 to 22.9)	14.6^f (13.6 to 15.6)	28.7(27.5 to 29.9)	21.5(20.6 to 22.3)	29.5^g (26.1 to 33.0)	23.5(20.9 to 26.1)	23.8(22.4 to 25.3)	23.9 (22.0 to 25.8)	21.2(19.4 to 22.9)	18.9(17.0 to 20.8)	21.5(20.0 to 23.0)
Mean age for CHD diagnosis (SD)	60.1 (11.3)	64.3^f(11.5)	58.2 (10.6)	61 (11.2)	53.1^g(9.7)	58.2^g(11.1)	60.4 (11)	59.8 (11.1)	59.6 (11.2)	62.5 (10.8)	59.1 (11.8)
Stroke
n (prevalence,%)	759 (7.4)	308 (6.7)	451 (8.0)	658 (8.0)	38 (4.8)	62 (5.1)	213 (7.6)	146 (9.1)	101 (5.3)	99 (7.0)	200 (7.9)
Adjusted prevalence (95% CI)^a	7.4 (6.9 to 7.9)	6.1^f (5.4 to 6.7)	8.7 (7.9 to 9.4)	7.4 (6.8 to 7.9)	8.0 (5.6 to 10.4)	7.5 (5.7 to 9.3)	7.3 (6.4 to 8.2)	8.8 (7.5 to 10.1)	5.6^h (4.6 to 6.6)	6.6 (5.4 to 7.8)	8.5 (7.4 to 9.6)
Mean age for stroke diagnosis (SD)	64.5 (12.8)	67.7^f(12.6)	62.3 (12.4)	65.3 (12.5)	58.3^g(11.6)	59.9^g(13.7)	64.5 (12.6)	64.6 (13.3)	63.5 (12.4)	66.8 (12.3)	63.8 (12.9)
Atrial fibrillation
n (prevalence,%)	995 (9.7)	404 (8.8)	591 (10.5)	901 (11.0)	24 (3.0)	69 (5.7)	289 (10.4)	162 (10.1)	157 (8.3)	152 (10.7)	235 (9.3)
Adjusted prevalence (95% CI)^a	9.7(9.2 to 10.3)	7.8^f (7.0 to 8 5)	11.7(10.8 to 12.6)	9.9(9.3 to 10.6)	6.2^g (3.9 to 8.6)	9.2(7.3 to 11.2)	9.7(8.6 to 10.7)	9.5(8.1 to 10.9)	8.8 (7.5 to 10.0)	10.0(8.5 to 11.6)	10.6(9.3 to 11.9)

The GEE logistic regression was used to adjust for differences in prevalence between groups. The significance level was set at 0.017 based on the Bonferroni correction. Mean differences between groups were analysed with independent sample t-test and ANOVA.
^aTotal prevalence (valid per cent) adjusted for clustering between practices. ^bSex adjusted for clustering and age; ^cEthnic group adjusted for clustering, age, and sex. ^dEthnic groups: (1) Norwegian (born in Norway); (2) South Asian (born in Pakistan, India, Sri Lanka, and Bangladesh); and (3) other (born in other countries). ^eCounty adjusted for clustering, age, sex, and ethnic group. ^fP<0.017 – difference between sex (reference = males). ^gP<0.017 – difference between ethnic groups (reference = Norwegian). ^hP<0.017 – difference between counties (reference = Oslo).
ANOVA = analysis of variance. CHD = coronary heart disease. GEE = generalised estimating equations. PCI = percutaneous coronary intervention (blocking). SD = standard deviation.

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Table 2. Proportion of patients with type 2 diabetes attaining treatment targets^a for HbA1c, SBP, lipids, and smoking, stratified by patient status regarding CHD and stroke

Attained targets^a			With CHD, %(n = 2260)	Without CHD, %(n = 7970)	With stroke, %(n = 759)	Without stroke, %(n = 9480)
Targets and other cut-off values		Valid cases (%)
HbA1c^a
≤ 7.0% (≤ 53 mmol/mol)		89	58.6^c	62.7	61.4	61.8
> 9.0% (>75 mmol/mol)			6.7	6.1	6.7	6.1
Systolic blood pressure (SBP)^a
Percent attaining overall SBP target		74	65.1	65.7	66.7	65.6
SBP >140 mmHg		87	29.0	28.6	27.4	28.8
Lipids^a
LDL-cholesterol ≤1.8(mmol/l)		68	30	-	-	-
LDL-cholesterol <2.5(mmol/l)		68	67.9^c	41.5	64.3^c	46.2
Lifestyle
No daily smoking		83	79.1^b	76.9	76.4	77.5
Proportions achieving specified number of targets
	Achieving no target		8.0	10.8	8.4	8.9
	Achieving one target		92.0	90.5	91.6	91.1
	Achieving two targets		63.3	64.9	66.7	66.3
	Achieving three targets		27.9	29.8	33.7	31.7
	Achieving four targets		5.0	6.0	7.9	7.0

Significance tests used are χ2 tests for categorical variables. ^aTreatment targets for patients with CHD are: HbA1c <7.0%, SBP target <135 mmHg medicated or <140 mmHg unmedicated, LDL-cholesterol <1.8 mmol/l, no smoking. For patients without CHD, the intervention threshold for LDL-cholesterol are LDL >3.5 mmol/l, with treatment target LDL <2.5 mmol/l. ^bP<0.05, ^cP<0.001.
CHD = coronary heart disease. LDL = low-density lipoprotein. SBP = systolic blood pressure.

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Table 3. Prescriptions during the last 15 months for primary and secondary prevention in patients with type 2 diabetes, CHD, and stroke.

Treatment		Primary prevention			Secondary prevention
Treatment		No CVD, % n = 7511	Females, % n = 3687	Males, % n = 3824	CHD, % n = 2260	Stroke, % n = 759
Attained SBP targets		65.7	64.1	67.0^a	65.1	66.7
Blood pressure medication
	Thiazides	26.4	28.2	23.9	25.8	26.7
	ACE inhibitors or aII-receptor blockers	47.7	48.7	46.8	61.5^b	58.0^b
	Calcium channel blockers (dihydropyridines)	23.1	22.3	23.8	29.1^b	34.1^b
	Beta-blockers	16.9	19.0	14.9^b	65.6^b	46.1^b
	Other BP medication	1.6	1.2	2.0^a	2.9^b	2.2
	Mean number of BP medications (SD)	1.2 (1.3)	1.3	1.2	2.1 (1.4)^d	1.9 (1.4)^d
	No BP medication	42.8	39.5	46.0^b	15.8^b	21.6^b
	Patients with SBP above target, and not prescribed medication	26.9	-	-	14.3	17.3
Attainment of LDL target		-	-	-	30	-
Lipid-lowering medication
	Statin	45.5	45.6	45.4	76.7^b	66.8^b
	Ezetimibe	1.6	1.9	1.3^a	4.7^b	2.6
	No lipid-lowering medication	53.9	53.7	54.0	22.7^b	32.7^b
Anti-platelet therapy		22.8	21.6	24.1^a	74.6^b	66.3^b

Significance test performed with Poisson regression analysis comparing medication for males versus females, CHD versus non-CHD patients, and stroke versus non-stroke patients, respectively.
^aP<0.05. ^bP<0.001. Significance test performed with χ² test comparing males versus females, CHD versus non-CHD, stroke versus non-stroke, respectively.^cP<0.05.^dP<0.001.
ACE = angiotensin-converting enzyme. BP = blood pressure. CHD = coronary heart disease. CVD = cardiovascular disease. LDL = low-density lipoprotein. SBP = systolic blood pressure. SD = standard deviation.

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Table 4. Associations between patient factors (including county of residence and education) and factors related to the GP, and the probability of achieving treatment targets for intermediate outcomes in patients with CHD and T2DM.^a

Covariates	SBP ≤135 or <140^b	LDL-cholesterol ≤1.8 mmol/l	HbA1c ≤7.0%	No daily smoking
Covariates	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
Patient factors
Age (per one year)	1.03 (1.02 to 1.04)^d	1.00 (0.99 to 1.01)	1.00 (0.99 to 1.01)	1.06 (1.05 to 1.08)^d
Sex (male = reference)	1.42 (1.16 to 1.74)^d	0.64 (0.50 to 0.82)^d	1.11 (0.92 to 1.35)	0.97 (0.73 to 1.28)
Socioeconomic factors
County (Oslo = reference)
Akershus	0.98 (0.59 to 1.61)	0.79 (0.54 to 1.15)	0.98 (0.65 to 1.47)	1.14 (0.75 to 1.72)
Rogaland	1.05 (0.61 to 1.78)	0.94 (0.67 to 1.33)	1.07 (0.81 to 1.44)	1.11 (0.74 to 1.67)
Hordaland	1.02 (0.61 to 1.72)	0.97 (0.71 to 1.34)	0.94 (0.67 to 1.32)	0.89 (0.59 to 1.34)
Nordland	1.41 (0.85 to 2.35)	0.60 (0.42 to 0.85)^d	0.94 (0.74 to 1.19)	1.26 (0.83 to 1.93)
Education (Primary/no education = reference)
Secondary education	1.08 (0.86 to 1.35)	1.10 (0.86 to 1.40)	1.12 (0.94 to 1.34)	1.26 (0.96 to 1.65)
University	0.95 (0.67 to 1.33)	1.14 (0.83 to 1.56)	1.34 (1.02 to 1.76)^c	1.76 (1.18 to 2.61)^c
Ethnic group (Norwegian = reference)
South Asian	0.94 (0.63 to 1.41)	1.21 (0.82 to 1.80)	0.45 (0.29 to 0.7)^d	1.91 (1.19 to 3.06)^c
Other	1.05 (.72 to 1.54)	1.16 (0.79 to 1.58)	0.60 (0.42 to 0.86)^c	1.06 (0.67 to 1.68)
GP factors
Specialty (Yes = reference)
No	1.24 (0.91 to 1.69)	0.95 (0.72 to 1.26)	0.92 (0.76 to 1.13)	1.15 (0.85 to 1.55)
Sex (Males = reference)
Females	0.81 (0.59 to 1.11)	1.20 (0.91 to 1.57)	1.02 (0.85 to 1.22)	1.34 (1.05 to 1.70)^c

^aMultilevel binary logistic regression analyses with four dependent variables in 2260 T2DM patients with CHD, adjusted for clustering between practices. ^bSystolic blood pressure targets: <140 mmHg for patients not using antihypertensives, and <135 mmHg when medication is prescribed. ^cP<0.05. ^dP<0.001.
CI = confidence intervals. CHD = coronary heart disease. LDL = low-density lipoprotein. OR = odds ratio. SBP = systolic blood pressure. T2DM = type 2 diabetes mellitus.