Christopher E Clark

Association of a difference in systolic blood pressure between arms with vascular disease and mortality: a systematic review and meta-analysis

BACKGROUND Differences in systolic blood pressure (SBP) of 10 mm Hg or more or 15 mm Hg or more between arms have been associated with peripheral vascular disease and attributed to subclavian stenosis. We investigated whether an association exists between this difference and central or peripheral vascular disease, and mortality. METHODS We searched Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, Cochrane, and Medline In Process databases for studies published before July, 2011, showing differences in SBP between arms, with data for subclavian stenosis, peripheral vascular disease, cerebrovascular disease, cardiovascular disease, or survival. We used random effects meta-analysis to combine estimates of the association between differences in SBP between arms and each outcome. FINDINGS We identified 28 eligible studies for review, 20 of which were included in our meta-analyses. In five invasive studies using angiography, mean difference in SBP between arms was 36·9 mm Hg (95% CI 35·4-38·4) for proven subclavian stenosis (>50% occlusion), and a difference of 10 mm Hg or more was strongly associated with subclavian stenosis (risk ratio [RR] 8·8, 95% CI 3·6-21·2). In non-invasive studies, pooled findings showed that a difference of 15 mm Hg or more was associated with peripheral vascular disease (nine cohorts; RR 2·5, 95% CI 1·6-3·8; sensitivity 15%, 9-23; specificity 96%, 94-98); pre-existing cerebrovascular disease (five cohorts; RR 1·6, 1·1-2·4; sensitivity 8%, 2-26; specificity 93%, 86-97); and increased cardiovascular mortality (four cohorts; hazard ratio [HR] 1·7, 95% CI 1·1-2·5) and all-cause mortality (HR 1·6, 1·1-2·3). A difference of 10 mm Hg or higher was associated with peripheral vascular disease (five studies; RR 2·4, 1·5-3·9; sensitivity 32%, 23-41; specificity 91%, 86-94). INTERPRETATION A difference in SBP of 10 mm Hg or more, or of 15 mm Hg or more, between arms might help to identify patients who need further vascular assessment. A difference of 15 mm Hg or more could be a useful indicator of risk of vascular disease and death. FUNDING Royal College of General Practitioners, South West GP Trust, and Peninsula Collaboration for Leadership in Applied Health Research and Care.

Nurse led interventions to improve control of blood pressure in people with hypertension: systematic review and meta-analysis.

Objective To review trials of nurse led interventions for hypertension in primary care to clarify the evidence base, establish whether nurse prescribing is an important intervention, and identify areas requiring further study. Design Systematic review and meta-analysis. Data sources Ovid Medline, Cochrane Central Register of Controlled Trials, British Nursing Index, Cinahl, Embase, Database of Abstracts of Reviews of Effects, and the NHS Economic Evaluation Database. Study selection Randomised controlled trials of nursing interventions for hypertension compared with usual care in adults. Data extraction Systolic and diastolic blood pressure, percentages reaching target blood pressure, and percentages taking antihypertensive drugs. Intervention effects were calculated as relative risks or weighted mean differences, as appropriate, and sensitivity analysis by study quality was undertaken. Data synthesis Compared with usual care, interventions that included a stepped treatment algorithm showed greater reductions in systolic blood pressure (weighted mean difference −8.2 mm Hg, 95% confidence interval −11.5 to −4.9), nurse prescribing showed greater reductions in blood pressure (systolic −8.9 mm Hg, −12.5 to −5.3 and diastolic −4.0 mm Hg, −5.3 to −2.7), telephone monitoring showed higher achievement of blood pressure targets (relative risk 1.24, 95% confidence interval 1.08 to 1.43), and community monitoring showed greater reductions in blood pressure (weighted mean difference, systolic −4.8 mm Hg, 95% confidence interval −7.0 to −2.7 and diastolic −3.5 mm Hg, −4.5 to −2.5). Conclusions Nurse led interventions for hypertension require an algorithm to structure care. Evidence was found of improved outcomes with nurse prescribers from non-UK healthcare settings. Good quality evidence from UK primary health care is insufficient to support widespread employment of nurses in the management of hypertension within such healthcare systems.

Prevalence and clinical implications of the inter-arm blood pressure difference: a systematic review

A blood pressure (BP) difference between arms was first reported over 100 years ago. Knowledge of its prevalence and relevance to the accurate measurement of BP remains poor. Current hypertension guidelines do not emphasise it. The objectives of this study were to establish the best estimate of prevalence of the inter-arm difference (IAD) in the population, to consider its implications for accurate BP measurement and treatment, and to discuss its aetiology and potential as a risk marker for cardiovascular disease. Systematic literature review was carried out. The data sources were Medline EMBASE and CINAHL databases, and Index of Theses. Studies reporting prevalence rates of IAD were retrieved and considered for inclusion against explicit methodological criteria. Point prevalence rates were extracted and weighted mean prevalence rates calculated. The main outcome measures were weighted mean prevalences of systolic IAD⩾10 and ⩾20 mm Hg and of diastolic IAD⩾10 mm Hg. Thirty-one studies were identified. Most had methodological weaknesses; only four met the inclusion criteria. Pooled prevalences of the IAD from these four studies were 19.6% systolic ⩾10 mm Hg (95% CI 18.0–21.3%), 4.2% systolic ⩾20 mm Hg (95% CI 3.4–5.1%) and 8.1% diastolic ⩾10 mm Hg (95%CI 6.9–9.2%). In conclusion, an IAD is present in a substantial number of patients and should be looked for whenever diagnosis and treatment depend on accurate measurements of BP. The importance of an IAD should be better emphasised in current hypertension management guidelines. There is evidence associating an IAD with peripheral vascular disease, raising the possibility that its presence may predict cardiovascular events.

The difference in blood pressure readings between arms and survival: primary care cohort study

Objective To determine whether a difference in systolic blood pressure readings between arms can predict a reduced event free survival after 10 years. Design Cohort study. Setting Rural general practice in Devon, United Kingdom. Participants 230 people receiving treatment for hypertension in primary care. Intervention Bilateral blood pressure measurements recorded at three successive surgery attendances. Main outcome measures Cardiovascular events and deaths from all causes during a median follow-up of 9.8 years. Results At recruitment 24% (55/230) of participants had a mean interarm difference in systolic blood pressure of 10 mm Hg or more and 9% (21/230) of 15 mm Hg or more; these differences were associated with an increased risk of all cause mortality (adjusted hazard ratio 3.6, 95% confidence interval 2.0 to 6.5 and 3.1, 1.6 to 6.0, respectively). The risk of death was also increased in 183 participants without pre-existing cardiovascular disease with an interarm difference in systolic blood pressure of 10 mm Hg or more or 15 mm Hg or more (2.6, 1.4 to 4.8 and 2.7, 1.3 to 5.4). An interarm difference in diastolic blood pressure of 10 mm Hg or more was weakly associated with an increased risk of cardiovascular events or death. Conclusions Differences in systolic blood pressure between arms can predict an increased risk of cardiovascular events and all cause mortality over 10 years in people with hypertension. This difference could be a valuable indicator of increased cardiovascular risk. Bilateral blood pressure measurements should become a routine part of cardiovascular assessment in primary care.

The interarm blood pressure difference as predictor of cardiovascular events in patients with hypertension in primary care: cohort study

Objectives of this study were to measure the prevalence of a difference in blood pressure (BP) between arms and determine whether a difference is associated with increased risk of cardiovascular events or death. A prospective cohort study of 247 patients with hypertension was undertaken in one rural general practice in England. The main outcome measures were mean difference in BP between arms and new episodes of myocardial infarction, cerebrovascular event, onset of angina or peripheral vascular disease or death. A total of 57/247 (23%) patients had a mean difference in systolic BP between arms of ⩾10 mm Hg and 8/247 (3%) had a mean difference of ⩾20 mm Hg. A total of 15/247 (6%) patients had a mean difference in diastolic BP between arms of ⩾10 mm Hg. Survival analysis after 4.7 years (range 3.3–5.9) showed a shorter mean survival time without event or death for patients with a difference in systolic BP of ⩾10 mm Hg compared with a difference of <10 mm Hg (3.7 (95% confidence interval, 3.2–4.2) versus 4.8 (4.6–5.1) years; P<0.001; hazard ratio 2.5 (1.5–4.2), P=0.001). Difference in systolic BP of ⩾10 mm Hg between arms is common in this primary care population and is associated with a shorter survival time to death or new cardiovascular event. Detection of a difference between arms may identify hypertensive patients at increased risk of cardiovascular events. Such an approach would allow more effective targeting of resources in primary prevention strategies.

Herbal interventions for chronic asthma in adults and children: a systematic review and meta-analysis.

AIMS To assess the efficacy of herb and plant extracts in the management of asthma. METHOD Systematic review and meta-analysis. Multiple database searches identified randomised placebo controlled trials of herbal interventions reporting at least one primary outcome measure. Where possible data were combined for meta-analysis. Primary outcome measures were lung function, exacerbations and reduction in corticosteroid use. Secondary outcome measures were symptoms and symptom scores, use of reliever medications, changes in rates of consultation and adverse effects. RESULTS Twenty-six studies reporting on 20 herbal preparations were included. Two of six studies reporting change in FEV1 were positive. Little data was available on frequency of exacerbations. For primary outcomes single studies of Boswellia, Mai-Men-Dong-Tang, Pycnogenol, Jia-Wei-Si-Jun-Zi-Tang and Tylophora indica showed potential to improve lung function, and a study of 1.8-Cineol (eucalyptol) showed reduced daily oral steroid dosage. CONCLUSIONS Improvements in symptoms were not strongly supported by objective changes. Most trials were of small sample size, short duration, and poor methodology. Further adequately powered trials are needed to assess these compounds. Such trials should conform to CONSORT guidance, report standardised spirometry, and use validated symptom and severity scores. No recommendations for herbal treatment of asthma can be made from the current evidence.

Nurse-led interventions used to improve control of high blood pressure in people with diabetes: a systematic review and meta-analysis

Diabet. Med. 28, 250–261 (2011)

Interarm Blood Pressure Difference in People With Diabetes: Measurement and Vascular and Mortality Implications A Cohort Study

OBJECTIVE Differences in blood pressure between arms are associated with vascular disease and increased mortality; this has not been reported in diabetes. We explored these associations, and assessed reference standard and pragmatic measurement techniques, in people with diabetes and in nondiabetic controls. RESEARCH DESIGN AND METHODS A prospective cohort study in Devon, England, recruited 727 people with type 1 or type 2 diabetes and 285 nondiabetic controls. Simultaneous repeated measurements of bilateral blood pressure were made at recruitment. Data were used to inform a pragmatic measurement strategy. Interarm differences were examined for cross-sectional associations with target organ disease and prospective mortality associations (median follow-up 52 months). RESULTS We found 8.6% of participants with diabetes and 2.9% of controls had systolic interarm differences ≥10 mmHg. Single pairs of blood pressure measurements had high negative predictive values (97–99%) for excluding interarm differences. Systolic interarm differences ≥10 mmHg in diabetes were associated with peripheral arterial disease (odds ratio [OR] 3.4 [95% CI 1.2–9.3]). Differences ≥15 mmHg were associated with diabetic retinopathy (OR 5.7 [1.5–21.6]) and chronic kidney disease (OR 7.0 [1.7–29.8]). Systolic interarm differences were associated prospectively with increased cardiovascular mortality: hazard ratios 3.5 (1.0–13.0) for ≥10 mmHg and 9.0 (2.0–41.0) for ≥15 mmHg. CONCLUSIONS Blood pressure should be measured in both arms during initial assessment in diabetes. Systolic interarm differences can be excluded with a single pair of measurements. In the population with diabetes, systolic differences may be associated with an increased risk of morbidity and mortality.

Inter-arm blood pressure difference in type 2 diabetes: a barrier to effective management?

BACKGROUND Previous studies have identified a substantial prevalence of a blood pressure difference between arms in various populations, but not patients with type 2 diabetes. Recognition of such a difference would be important as a potential cause of underestimation of blood pressure. AIM To measure prevalence of an inter-arm blood pressure difference in patients with type 2 diabetes, and to estimate how frequently blood pressure measurements could be erroneously underestimated if an inter-arm difference is unrecognised. DESIGN OF STUDY Cross-sectional study. SETTING Five surgeries covered by three general practices, Devon, England. METHOD Patients with type 2 diabetes underwent bilateral simultaneous blood pressure measurements using a validated protocol. Mean blood pressures were calculated for each arm to derive mean systolic and diastolic differences, and to estimate point prevalence of predefined magnitudes of difference. RESULTS A total of 101 participants were recruited. Mean age was 66 years (standard deviation [SD] = 13.9 years); 59% were male, and mean blood pressure was 138/79 mmHg (SD = 15/10 mmHg). Ten participants (10%; 95% confidence interval [CI] = 4 to 16) had a systolic inter-arm difference > or =10 mmHg; 29 (29%; 95% CI = 20 to 38) had a diastolic difference >/=5 mmHg; and three (3%; 95% CI = 0 to 6) a diastolic difference > or =10 mmHg. No confounding variable was observed to account for the magnitude of an inter-arm difference. CONCLUSION A systolic inter-arm difference > or =10 mmHg was observed in 10% of patients with diabetes. Failure to recognise this would misclassify half of these as normotensive rather than hypertensive using the lower-reading arm. New patients with type 2 diabetes should be screened for an inter-arm blood pressure difference.

Asthma after childhood pneumonia: six year follow up study

Abstract Objective: To establish the long term cumulative prevalenceof asthma in children admitted to hospital with pneumonia and to examine the hypothesis that some children admitted to hospital with pneumonia may be presenting with undiagnosed asthma. Design: Prospective study of a cohort of children previously admitted to hospital with pneumonia, followed up by postal questionnaires totheir general practitioners and the children or their parents. Setting: General practices in southwest England. Participants: 78 children admitted to the Royal Devon and Exeter Hospital between 1989 and 1991 with a diagnosis of pneumonia confirmed on independent review of x ray films. Main outcome measures: Any diagnosis of asthma, use of any treatment for asthma, and asthma symptom scores. Results: On the basis of a 100% response rate from general practitioners and 86% from patients or parents, the cumulative prevalence of asthma was 45%. A diagnosis of asthma was associated with a family history of asthma (odds ratio 11.23; 95% confidence interval 2.57 to 56.36; P=0.0002). Mean symptom scores were higher for all children with asthma (mean score 2.4; χ2=14.88; P=0.0001)and for children with asthma not being treated (mean 1.4; χ2=6.2; P=0.01)than for those without asthma (mean 0.2) Conclusions: A considerable proportion of children presenting to a district general hospital with pneumonia either already have unrecognised asthma or subsequently develop asthma. The high cumulative prevalence of asthma suggests that careful follow up of such children is worth while. Asthma is undertreated in these children; a structured symptom questionnaire may help to identify and reduce morbidity due to undertreatment.