A cluster randomised controlled trial of the effect of a treatment algorithm for hypertension in patients with type 2 diabetes

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Figure 1
Algorithm for the management of hypertension
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Figure 2
Flow of participants through the study

Table 1

Baseline characteristics of participants: n (%) unless otherwise stated.

Participant characteristics	Intervention arm n = 797	Control arm n = 737
Mean age (SD)	64.3 (9.9)	64.3 (10.0)

Males	464 (58.2)	443 (60.1)

Ethnic group: non-white	61 (7.7)	83 (11.3)

Years since diagnosis of diabetes
0–5	437 (54.8)	395 (53.6)
6–10	184 (23.1)	190 (25.8)
11–15	107 (13.4)	85 (11.5)
>15	69 (8.7)	67 (9.1)

Diabetes controlled by
Diet	191 (24.0)	150 (20.4)
Oral medication	504 (63.2)	497 (67.4)
Insulin	102 (12.8)	90 (12.2)

Mean systolic blood pressure (SD) [3]	146 (21)	146 (19)

Mean diastolic blood pressure (SD) [3]	80 (10)	80 (10)

Controlled blood pressure [3]	264 (33.3)	228 (30.9)

Receiving treatment for hypertension	540 (67.8)	505 (68.5)

Number of antihypertensive medications:
0	257 (32.3)	232 (31.5)
1	199 (25.0)	191 (25.9)
2	204 (25.6)	185 (25.1)
3	103 (12.9)	89 (12.1)
4	30 (3.8)	36 (4.9)
5	3 (0.4)	3 (0.4)
6	1 (0.1)	1 (0.1)
Median (IQR)	1 (0,2)	1(0,2)

Prescribed >50% of maximum dose of antihypertensives^a	269 (50.6)	260 (52.6)

Mean body mass index (SD)[2]	30.0 (5.3)	30.2 (3.4)

Current smoker [1]	119 (14.9)	104 (14.1)

Macrovascular complications^b	263 (33.0)	228 (30.9)

Microvascular complications^c[173]	314 (44.6)	292 (44.4)

Mean glycosylated haemoglobin (SD) [10]	7.7 (1.4)	7.7 (1.5)

↵a Calculated by summing percentage of maximum recommended dose prescribed for each antihypertensive drug and dividing by number of prescribed antihypertensive drugs. Loop diuretics have been excluded from this analysis.
↵b Defined as a history of ischaemic heart disease, cerebrovascular disease, or peripheral vascular disease.
↵c Defined as the presence of retinopathy, abnormal albumin creatinine ratio or peripheral neuropathy. IQR = interquartile range. [] = missing values. SD = standard deviation.

Table 2

Baseline characteristics of practices.

Practice characteristics	Intervention arm n = 20	Control arm n = 22
	Median (IQR)	Median (IQR)

List size	4615 (2969–7056)	5593 (2475–6834)

Number of WTE GPs	3.0 (1.4–3.7)	2.8 (1.0–3.3)

Number of WTE nurses	1.5 (1.1–2.0)	1.5 (1.0–2.0)

Number of patients with diabetes	134 (68–196)	127 (73–183)

Practice Townsend score [1]	0.06 (−0.73–2.85)	−0.19 (−1.49–2.87)

Percentage of practice population from non-white ethnic group [1]	6.3 (3.1–8.2)	6.8 (2.7–10.2)

	n (%)	n (%)

Practice has agreed BP target	14 (70.0)	21 (95.5)

BP target agreed by practice, mmHg
<140/80	13 (92.9)	17 (81.0)
140/80–160/95	1 (7.1)	4 (19.1)

Practice negotiates targets with
Almost all or many patients	12 (60.0)	11 (50.0)
A few or hardly any patients	8 (40.0)	11 (50.0)

[] = missing values. BP = blood pressure. IQR = interquartile range. WTE = whole time equivalent.

Table 3

Primary and secondary outcome measures comparing intervention arm to control arm: n (%) unless stated otherwise.

	Intervention arm n = 743	Control arm n = 677	ICC	OR (95% CI)	P-value
Primary outcome measure

Controlled blood pressure	272 (36.6)	232 (34.3)	0.035	1.23 (0.85 to 1.78)	0.27

Secondary outcome measures

Categorical outcome measures				OR (95% CI)

BP <140/80mmHg	245 (33.0)	202 (29.8)	0.041	1.27 (0.86 to 1.89)	0.23

Prescribed antihypertensives	526 (70.8)	471 (69.6)	0.050	1.30 (0.85 to 1.97)	0.23

Prescribed >50% of max dose of antihypertensives	301 (58.2)	248 (53.1)	0.033	1.50 (1.03 to 2.17)	0.03

Satisfied with care (versus neither/dissatisfied) [161]	560 (83.7)	504 (85.4)	0.007	0.84 (0.59 to 1.19)	0.32

Continuous outcome measures				Difference between means (95% CI)

Mean systolic BP (SD)	143.3 (19.5)	143.1 (17.7)	0.034	−1.30 (−4.43 to 1.83)	0.42

Mean diastolic BP (SD)	78.2 (10.2)	77.9 (10.4)	0.039	−0.11 (−1.78 to 1.56)	0.90

Count outcome measures				RR (95% CI)

Number of antihypertensive drugs prescribed			0.054	1.07 (0.91 to 1.26)	0.42
0	217 (29.2)	206 (30.4)
1	180 (24.2)	157 (23.2)
2	181 (24.4)	165 (24.4)
3	115 (15.5)	111 (16.4)
4	41 (5.5)	27 (4.0)
5	6 (0.8)	9 (1.3)
6	3 (0.4)	2 (0.3)
Median (IQR)	1(0,2)	1(0,2)

Number of BP consultations [17]			0.174	1.50 (1.25 to 1.80)	<0.001
0	24 (3.3)	54 (8.1)
1	73 (10.0)	122 (18.2)
2	108 (14.7)	114 (17.0)
3	117 (16.0)	99 (14.8)
4	91 (12.4)	89 (13.3)
5	82 (11.2)	63 (9.4)
≥6	238 (32.5)	129 (19.3)
Rate/year	4.9	3.7