A review of the medical treatment of primary aldosteronism

PURPOSE

Use of the aldosterone-to-renin ratio (ARR) has suggested that at least one in 10 hypertensive subjects have primary aldosteronism (PA). There is thus a timely need to review the literature for effective drug therapies and to speculate on other therapeutic options by taking into account recent advances in understanding of the PA disease pathophysiological process.

DATA SOURCE

A MEDLINE and EMBASE search of all articles published from the start of the databases until July 1999 and reviews of the bibliographies of textbooks.

STUDY SELECTION

Primary research articles on the medical treatment of PA with emphasis on diagnosis, treatment option, drug dosage, therapeutic response and adverse drug effect.

DATA EXTRACTION

Study design and quality were assessed. Relevant data on diagnostic methodology, drug usage and response were analysed and compared.

DATA SYNTHESIS

A select number of subjects with aldosterone-producing adenoma (APA) can be expected to respond well to surgical treatment For the majority of PA cases especially subjects with idiopathic hyperaldosteronism (IHA), long-term medical treatment is now safe and feasible although no randomized controlled trials have been carried out to date. The best therapeutic response is obtained by directly antagonizing aldosterone at the receptor level using medium to low dose spironolactone and this response can be predicted by a raised ARR. The response to other potassium-sparing diuretics and calcium channel blockers are modest. IHA responds better than angiotensin II-unresponsive APA to angiotensin converting enzyme inhibitors and this may also be true with angiotensin II receptor blockers. The discovery of the aldosterone synthase gene opens up the possibility for gene therapy.

CONCLUSION

The diagnosis of PA allows appropriate management with resultant blood pressure control in many hypertensive subjects who otherwise have resistant hypertension despite multiple drug therapy.

Isolated diastolic heart failure as a cause of breathlessness in the community: the Arbroath study

The aim of this study was to examine the prevalence of exercise limitation due to diastolic heart failure among patients felt to have cardiac breathlessness by their general medical practitioner but not referred to hospital. We found that 18% of patients had a simple investigated profile compatible with isolated diastolic dysfunction as a cause of their symptoms. Symptoms appeared to pre-date major cardiac events (infarction; stroke; arrhythmia) that dominated the subsequent clinical course. The patients in this group have adverse cardiovascular risk profiles. Obesity was a common co-morbidity which may impair detailed 2-D echocardiographic assessment.

Exercise blood pressure correlates with the maximum heart rate corrected QT interval in hypertension

Submaximal exercise systolic blood pressure (ExSBP) is a recognised predictor of cardiac mortality. This study examined the possibility that this might be related to increased QT dispersion or prolonged maximum QT(c) interval (QTcmax). Twenty-nine untreated hypertensive subjects were assessed. Each subject underwent an echocardiographic examination and a 24-h ambulatory blood pressure (ABP). ExSBP was measured during a 3-min lightweight submaximal Dundee step test. In multiple regressional analyses, only left ventricular mass index significantly predicted QT dispersion (R2 = 22.4%, P = 0.018) and QT(c) dispersion (R(2) = 25.3%, P = 0.012). However, with respect to QTcmax, ExSBP (R2 = 21.6%, P = 0.02) emerged as the sole significant predictor of this index. Five (17.2%) out of the 29 subjects had prolonged QTcmax > or = 430 ms and these subjects were not differentiated by 24-h ABP (146 (s.d. 21)/83 (16) vs 140 (14)/88 (11) mm Hg, P = Ns) but by ExSBP (226 (15) vs 188 (24) mm Hg, P = 0.002). In conclusion, systolic blood pressure measured during exercise correlated with QT(c) max in hypertension. This finding may partly explain the prognostic value of exercise blood pressure.

Adverse cardiac effects of salt with fludrocortisone in hypertension

The effect of salt on blood pressure (BP) is controversial. A more important question is whether salt can produce cardiac target-organ damage, irrespective of its effect on BP. We assessed the effect of salt with fludrocortisone on QT dispersion and echocardiographic left ventricular diastolic function in a prospective interventional study involving 29 hypertensive subjects with a raised aldosterone/renin ratio who were hospitalized for investigation of possible primary aldosteronism. Each subject over 4 days was given a total of 28.8 g (480 mmol) of sodium chloride and 1.5 mg of fludrocortisone with potassium supplementation. Baseline and posttreatment 12-lead ECGs and echocardiograms were obtained. There were no significant changes in body weight, pulse rate, or BP after treatment with salt and fludrocortisone. Plasma sodium was significantly increased from 141.4 (SD 2.1) to 142.6 (SD 2.4) mmol/L (P:=0.001). QT and QTc dispersion both significantly increased: +19.6 (SD 16.5) ms (95% CI, 13.4 to 25.9) (P:<0.001) and +19.8 (SD 20.9) ms (95% CI, 11.8 to 27.7) (P:<0.001), respectively. There were no significant changes in (n=15) left ventricular dimensions or systolic function, but all diastolic filling indexes, including the preload-independent index, flow propagation velocity (55.49 [SD 10.91] to 48.96 [SD 11.40] cm/s, P:=0.018) worsened, suggesting significant deterioration of left ventricular diastolic function with salt and fludrocortisone. In conclusion, a combination of salt with fludrocortisone increased QT dispersion and impaired left ventricular diastolic relaxation in hypertensive patients with high aldosterone/renin ratios. This raises the possibility that salt may have BP-independent adverse cardiac effects in susceptible hypertensive subjects.

The multiple propensity score for analysis of dose-response relationships in drug safety studies

In order to detect adverse drug reactions, large observational drug safety studies are necessary as randomized clinical trials rarely have enough power. However, in order to obtain reliable results the issue of confounding, especially confounding by indication, should be addressed. We proposed a multiple propensity score, which is an extension of the propensity score, to reduce the bias in a dose-response analysis in a drug safety study. The multiple propensity score has similar properties to the propensity score in Rosenbaum and Rubin.(1) Using the propensity score for bias reduction of the risk ratio was considered. We used the multiple propensity score in a study of the dose-response relationship between diclofenac prescriptions and hospitalization for gastrointestinal bleeding and perforation using a record linkage database. We found that the unadjusted risk ratios were biased downwards due to confounders and that this bias was reduced by using stratification based on the multiple propensity score.

The prescribing of acid suppressants prior to the endoscopic diagnosis of Barrett's oesophagus and oesophagitis

BACKGROUND

There has been a dramatic rise in incidences of Barrett's oesophagus and oesophageal adenocarcinoma. It has been suggested that the introduction and use of acid suppression therapy may be a factor in the rising incidences of Barrett's oesophagus and oesophageal adenocarcinoma.

METHODS

This was a record linkage study, using a prescribing database and an endoscopy database. Patients who had undergone their first endoscopy during the period 1992-1995 and received the diagnosis of Barrett's oesophagus or oesophagitis were identified. The prescribing of acid suppressants was compared for the 3 years prior to endoscopy, between those with Barrett's oesophagus and those with oesophagitis.

RESULTS

There was no significant difference between the Barrett's patients and the oesophagitis patients in the proportion that had been exposed to acid suppression therapy (53.4% vs. 51.7%, P=0.704). The mean number of days of prescribing among those who had been exposed to acid suppression therapy was higher in the Barrett's group (340.5 vs. 237.0 days, P=0.001).

CONCLUSIONS

Patients with Barrett's oesophagus have received more acid suppressant therapy prior to diagnosis. The reasons for this are not clear. However, 46.6% of Barrett's patients have not been exposed to acid suppressant therapy.

Post exertional broad complex tachycardia in a normotensive patient: a rare presentation of phaeochromocytoma

Phaeochromocytomas are rare cause of secondary hypertension with significant morbidity and mortality, if left untreated. Paroxysms with hypertension are considered as "textbook" presentations but atypical forms represent considerable diagnostic challenge. We report an unusual association between phaeochromocyotoma and post-exertional malignant arrhythmia in a normotensive subject.

Effect of diuretics on fetal growth: A drug effect or confounding by indication? Pooled Danish and Scottish cohort data

AIMS

The diabetogenic effect of diuretics, as well as the indication for prescribing them, may impact on fetal growth. We analysed whether the purchase of prescription drugs for diuretics during pregnancy was associated with measures of fetal growth.

METHODS

During 1991-98 all women who purchased prescription drugs for diuretics during pregnancy were identified in the Northern Jutland Prescription Database (NJDP), Denmark, and in the Medicines Monitoring Unit's Database (MEMO), Scotland. Information on birth weight and gestational age was obtained from the Danish Birth Registry, the Danish Hospital Discharge Registry and the Scottish Tayside Neonatal Database. Information on diabetes, hypertension and prepregnancy weight were obtained by hospital record review in a sample of women in the Danish cohort. Women who did not purchase prescription diuretics during pregnancy were used as a reference group in both cohorts.

RESULTS

Danish women who purchased prescription loop diuretics during pregnancy gave birth to infants with higher birth weights than women who did not use diuretics; mean difference 104.7 g (95% CI; 2.6, 206.9). However, the high prevalence of diabetes (10.3%) among Danish women who purchased prescription loop diuretics during pregnancy might explain this result. Both the Danish and the Scottish women who purchased prescription diuretics during their pregnancy were at increased risk of preterm delivery (< 37 completed weeks); ORs: 1.8 (CI; 1.2, 2.7)NJDP, 1.9 (CI; 0.9, 4.3)MEMO. The proportion of hypertension among women who purchased prescription thiazides was 15.8%, and the risk of having an infant with a birth weight (BW) < 2500 g was increased; ORs: 2.6 (CI; 1.4, 5.0)NJDP, 2.4 (CI; 0.8, 7.8)MEMO.

CONCLUSIONS

Prescribing diuretics during pregnancy was associated with differences in birth weight and incidence of preterm delivery. Confounding by indication may explain the findings.

Aldosterone to renin ratio as a determinant of exercise blood pressure response in hypertensive patients

Aldosterone to renin ratio (ARR) is a marker of inappropriate aldosterone activity in hypertension. Since aldosterone may adversely affect vascular compliance, we hypothesised that the ARR would relate to exercise blood pressure (BP) responses in hypertension. Blood sampling was done in untreated hypertensives for plasma renin activity (PRA, ng/mL/hr) and plasma aldosterone (PA, pmol/L). ARR was derived by dividing the PA value by the PRA value, and this index was normalised by natural logarithm (lnARR) for further analyses. Each patient underwent 24-h ambulatory BP (ABP), and a 3-min submaximal exercise test using the Dundee Step Test. The Spearman rank correlation coefficients between lnARR and office BP (OBP), ABP and exercise BPs and BP changes estimated during exercise were assessed. A total of 119 (66 males) hypertensive subjects aged 48 (s.d. 12) years were studied. The respective OBP, ABP, exercise BP and the change in exercise BP were 167(23)/105(11), 140(15)/87(10), 189(26)/107(12) and 25(15)/2(9) mmHg. lnARR was significantly correlated with exercise systolic BP (r = 0.24, P < 0.001), exercise diastolic bp (r = 0.23, P < 0.05), systolic abp (r = 0.22, P < 0.05) and systolic obp (r = 0.19, P < 0.05). in a multiple regressional analysis controlling for age and sex and all other bp measurements to assess the relative strengths of correlation between all the bp indices with lnarr, only exercise systolic bp (P = 0.012) and the change in systolic BP during exercise (negatively, P = 0.013) emerged as significant independent predictors of lnARR. In conclusion, there was an independent and significant correlation between ARR and exercise systolic BP.

Nonadherence with ACE inhibitors is common and can be detected in clinical practice by routine serum ACE activity

Our objective was to assess whether serum angiotensin-converting enzyme (ACE) activity during routine clinical practice accurately reflects patient adherence to ACE inhibitor treatment in chronic heart failure (CHF). During 1994-95, ACE was measured in 73 CHF patients who were routinely attending the heart failure clinic at Ninewells Hospital. At the same time, the Medicines Monitoring Unit collected data on whether and when prescriptions for ACE inhibitors were redeemed at community pharmacies, which enabled each patient's adherence over a prolonged period to be assessed. We then correlated whether an elevation in serum ACE was associated with poor adherence with ACE inhibitor treatment. In total, 18% of CHF patients appeared to exhibit less than 70% adherence with their ACE inhibitor treatment, with 34% exhibiting less than 85%adherence and 58% exhibiting less than 100% adherence. A serum ACE activity of more than 12 U/L gave 91% positive predictive accuracy that the patient was less than 100% adherent with his or her ACE inhibitor treatment. At the other extreme, a serum ACE less than 6.5 U/L gave 81% positive predictive accuracy that the patient was more than 85% adherent with ACE inhibitor treatment. Nonadherence with ACE inhibitor treatment, therefore, was found to be common in patients with CHF. The simple, inexpensive test of serum ACE activity can be used in CHF patients to identify many, although not all, nonadherent patients so that adherence-enhancing strategies can be targeted toward them. Further work is clearly required to explore the precise clinical utility of this promising test. (c)2001 by CHF, Inc.

Selegiline and mortality in subjects with Parkinson's disease: a longitudinal community study

OBJECTIVE

To estimate mortality by drug use in a cohort of patients with PD relative to age- and sex-matched comparators.

METHODS

two longitudinal cohorts of patients with 7 and 11 years' duration of PD were constructed with matched comparators in Tayside, Scotland. Subjects were eligible for inclusion if they received a first prescription for an anti-Parkinson's drug from July 1989 to December 1995, with no PD drug prescription in the previous 6 months. Those who had previously taken a neuroleptic drug or were younger than 40 years of age were excluded.

RESULTS

Overall, subjects with PD in relation to comparators had higher mortality with a rate ratio (RR) of 1.76 (95% CI 1.11, 2.81) in the 7-year cohort. There was significantly greater mortality in patients with PD who received levodopa monotherapy (RR = 2.45, 95% CI 1.42, 4.23) relative to the comparators, adjusting for previous cardiovascular drug use and diabetes. However, there was no significant difference in mortality in those with PD receiving combination therapy of selegiline with levodopa and other drugs in relation to the comparators (RR = 0.92, 95% CI 0.37, 2.31).

CONCLUSIONS

Subjects with PD had twice the rate of mortality relative to age- and sex-matched comparators. However, those subjects who received selegiline at any time in combination with co-careldopa or co-beneldopa showed no significant difference in mortality compared with the comparators. Monotherapy with levodopa was associated with the highest mortality.

Epidemiology and pharmacoeconomic implications of non-steroidal anti-inflammatory drug-associated gastrointestinal toxicity

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely prescribed and used, especially to treat patients with osteoarthritis and rheumatoid arthritis. Since their introduction as a therapeutic class, a large body of literature has accumulated on the side-effects of these drugs. NSAIDs, through their inhibition of prostaglandin synthesis, can affect the renal and cardiovascular systems. However, the majority of reported side-effects are related to the gastrointestinal (GI) system, and the occurrence of these GI events adds significantly to the disease burden. Several factors have been identified that contribute to the risk of an NSAID-associated GI event. However, when considering risk, especially in clinical trials or observational studies, it is necessary to distinguish between baseline risk and NSAID-attributable risk, since this distinction can affect the results and conclusions of the study; NSAID-attributable risk is present in subjects who have few or no risk factors for upper GI toxicity. Safer NSAIDs, such as the new specific cyclooxygenase-2 inhibitors, when targeted to the appropriate patient (i.e. those with NSAID-attributable risk), should lead to improved outcomes and reduced costs.

Design issues for drug epidemiology

Despite the difficulties involved in designing drug epidemiology studies, these studies are invaluable for investigating the unexpected adverse effects of drugs. The aim of this paper is to discuss various aspects of study design, particularly those issues that are not easily found in either textbooks or review papers. We have also compared and contrasted drug epidemiology with the randomized controlled trial (RCT) wherever possible. Drug epidemiology is especially useful in the many situations where the RCT is not suitable, or even possible. The study base has to be defined before the appropriate cohort of subjects is assembled. If all of the cases are identified, then a referent sample of controls may be assembled by random sampling of the study base. If all of the cases cannot be assembled, a hypothetical secondary base may need to be created. Preferably, only new-users of the drug should be included, and the risk-ratio will be different for acute users and chronic users. Studies will usually only be possible when researching the unintended effects of drugs. It is difficult to study efficacy because of confounding by indication. In occasional circumstances it may be possible to study efficacy (examples are given). Discussion of the dangers of designing with generalisability in mind is provided. Additionally, the similarities in study design between drug epidemiology and the RCT are discussed in detail, as well as the design-characteristics that cannot be shared between the two methods.

The pharmacodynamic and pharmacokinetic profiles of controlled-release formulations of felodipine and metoprolol in free and fixed combinations in elderly hypertensive patients

AIMS

The aims of this study were to study the efficacy and tolerability of felodipine extended release (ER) 5 mg and metoprolol controlled release (CR/ZOC) 50 mg given as a fixed combination (Logimax) or as a free combination in elderly (age greater than 60 years) hypertensive patients, using ambulatory blood pressure (BP) monitoring. A secondary aim was to relate the efficacy of the free and fixed combinations with pharmacokinetic profiles.

METHODS

This was a double-blind, placebo-controlled randomised three-way crossover multi-centre study. BP was measured for 26 h using ambulatory blood pressure monitoring (ABPM), which was performed on the last day of the three treatment phases.

RESULTS

Mean sitting BPs, measured during the trough period with ABPM, were significantly lower with both the free and fixed combinations of metoprolol and felodipine than placebo (141/83 mmHg free, 140/83 mmHg fixed, 156/93 mmHg placebo). The mean BPs measured over 24 h using ABPM were 143/82 mmHg, 140/82 mmHg and 158/93 mmHg for the free, fixed and placebo treatment arms, respectively. The trough-to-peak ratios (T:P) were 75% and 79% for the systolic BP and 70% and 70% for the diastolic BP for the free and fixed combinations, respectively. Pharmacokinetic evaluation revealed identical plasma concentration-time curves for felodipine given as the free or fixed combination. Comparison of the plasma concentration-time curves for metoprolol revealed a delay in the release rate from the fixed combination formulation. No significant differences in BP control between the active treatments were noted during this period. Of 26 patients entered into the study, 3 withdrew during active phase for non-drug-related reasons. No patient withdrew from active treatment due to treatment-related adverse events. The frequency of adverse event reporting for the fixed combination of felodipine and metoprolol was similar to that for placebo (60% and 58%, respectively).

CONCLUSION

The results suggest that once-daily dosing with either the free or fixed combination of felodipine 5 mg and metoprolol 50 mg produces a significant sustained reduction in systolic and diastolic BP with similar plasma concentration profiles over a 24-h period.

Glaucoma incidence in an unselected cohort of diabetic patients: is diabetes mellitus a risk factor for glaucoma? DARTS/MEMO collaboration. Diabetes Audit and Research in Tayside Study. Medicines Monitoring Unit

AIMS

To evaluate whether diabetes mellitus is a risk factor for the development of primary open angle glaucoma or ocular hypertension (OHT).

METHODS

A historical cohort study of an unselected population comprising all residents of the Tayside region of Scotland was performed using record linkage techniques followed by case note review. Ascertainment of prevalent diabetes was achieved using the Diabetes Audit and Research in Tayside Study (DARTS) validated regional diabetes register. Glaucoma and treated OHT were defined by encashment of community prescriptions and the statutory surgical procedure coding database.

RESULTS

The study population comprised 6631 diabetic subjects and 166 144 non-diabetic subjects aged >40 years without glaucoma or OHT at study entry. 65 patients with diabetes and 958 without diabetes were identified as new cases of glaucoma or treated OHT during the 24 month study period, yielding a standardised morbidity ratio of 127 (95% CI, 96-158). Case note review demonstrated non-differential misclassification of prevalent glaucoma and OHT as incident disease (diabetic cohort 20%, non-diabetic cohort 24%; p=0.56) primarily as a result of non-compliance in medically treated disease. Removing misclassified cases and adjusting for age yielded an incidence of primary open angle glaucoma in diabetes of 1.1/1000 patient years (95% CI, 0.89-1. 31) compared to 0.7/1000 patient years (95% CI, 0.54-0.86) in the non-diabetic cohort; RR 1.57 (95% CI, 0.99-2.48).

CONCLUSIONS

This study failed to confirm an association between diabetes mellitus and primary open angle glaucoma and ocular hypertension. A non-significant increase in diagnosed and treated disease in the diabetic population was observed, but evidence was also found that detection bias contributes to this association.

The influence of physical activity on the variability of ambulatory blood pressure

The aim of this study was to assess the contribution of physical activity levels to blood pressure (BP) variability, and to assess the effect age, gender, body mass index, and use of antihypertensive medications on this relationship. We simultaneously monitored 24-h ambulatory BP by automated recorder and activity by actigraphy in 431 patients. Mean activity scores for the 5, 10, 15, and 20 min preceding each BP measurement were calculated, and BP and heart rate were related to these variables using linear mixed model regression. Various patient characteristics were added to the mixed model as covariates. Patients were heterogeneous in age (48 +/- 13 years), sex (49% men), and average 24-h BP (132/81 +/- 15/10 mm Hg). Mean daytime activity level was 44 +/- 15 U. During the daytime, systolic BP (r = 0.33), diastolic BP (r = 0.29), and heart rate (r = 0.42) correlated best with the average activity for the 15 min preceding each measurement (P < .001). Variance was very high, with activity explaining from 0% to 62% of BP variability for different individuals. Men and the obese had a greater reactivity of systolic BP to activity; older patients and those on antihypertensive therapy had a lower reactivity of heart rate. Blood pressure level is significantly associated with physical activity, but the percentage of variance of BP explained by physical activity varies greatly between individuals. Correlation is strongest between BP and average activity integrated over the previous 15 min. Much of the variance in blood pressure remains unexplained.

Practice factors that influence antibiotic prescribing in general practice in Tayside

A cohort design was used to evaluate antibiotic prescribing in relation to patient and general practice characteristics. The study included prescribing to all subjects resident in Tayside, from January to December 1994 and found 215217 antibiotic prescriptions dispensed to 118596 people. Training status of general practitioners (GPs) was found to be the characteristic most associated with prescribing. Adjusting for other GP characteristics had little effect on these results. Training practice status was the dominant factor associated with significant differences in rates of antibiotic prescribing, in class of antibiotic prescribed and in performance indicators of antibiotic prescribing.

Prevalence and aetiology of hypothyroidism in the young

AIMS

To define the prevalence of hypothyroid disease in children and young people, and describe its aetiology.

METHODS

We identified all patients on the Medicines Monitoring Unit (MEMO) database in the Tayside region of Scotland who had received two or more prescriptions for thyroxine during the study period (January 1993 to December 1995). Using this as a surrogate marker of hypothyroidism, we calculated the prevalence of hypothyroidism in those aged less than 22 years. Main outcome measures were prevalence of thyroxine prescription, estimated prevalence of hypothyroidism, and aetiology of the hypothyroidism (determined from case records, and biochemistry and immunology databases).

RESULTS

Of 103,500 residents aged less than 22 years, 140 were identified as receiving thyroxine on prescription, giving a population prevalence of 0.135%. The ratio of male to female was 1:2.8. Acquired hypothyroidism was the commonest aetiology found in 73%, 66% of which had an autoimmune basis. The prevalence of congenital hypothyroidism was 0.027%. Seven had received treatment for malignancy (two primary thyroid). Fifteen per cent of patients had no record of secondary care follow up in Tayside.

CONCLUSIONS

The overall prevalence of hypothyroidism in young people less than 22 years of age is 0.135%, and in the group aged 11-18 years it is 0.113%; these values are at least twice those of previous estimates. This suggests an increase in autoimmune thyroid disease, similar to the rising prevalence of type 1 diabetes, possibly indicating a rising incidence of autoimmunity in young people.

How well do office and exercise blood pressures predict sustained hypertension? A Dundee Step Test Study

Exercise systolic blood pressure (BP) appears to be a better predictor of cardiac mortality than casual office BP. We tested whether this could be explained by exercise systolic BP being a better predictor of sustained hypertension than casual office BP. Exercise systolic BP was measured using the lightweight 3-min single stage, submaximal Dundee Step Test in 191 consecutive subjects (102 male, age 52 (s.d. 13) years) who were referred to a specialist hypertension clinic for assessment. Exercise systolic BP was compared with office BP and daytime ambulatory BP (ABP). Sustained hypertension was defined as a mean daytime systolic and/or diastolic ABP of >/=140/90 mm Hg. Receiver operating characteristic (ROC) curves of exercise systolic BP and office BP in predicting sustained hypertension were compared. The positive predictive value of office diastolic BP >/=90 mm Hg and office systolic BP >/=140 mm Hg for sustained hypertension were 64% and 67% respectively. However, exercise systolic BP >/=180 mm Hg had a positive predictive value of 76%. Twenty-two percent (42/191) of subjects had an exercise systolic BP rise to >/=210 mm Hg, and 93% of this group had sustained hypertension on ABP. Whilst exercise systolic BP was a better predictor of sustained hypertension using currently recommended office BP treatment thresholds, the ROC curves of these indices were not different. In a multiple regression analysis, exercise systolic BP was an independent predictor of sustained hypertension, accounting for 36% of the variance of daytime systolic ABP after adjusting for age, gender and antihypertensive drug treatment. In conclusion, exercise systolic BP was a marginally better predictor of sustained hypertension than office BP. This may partly explain why exercise systolic BP is a potent predictor of cardiac mortality.

Socio-economic status, obesity and prevalence of Type 1 and Type 2 diabetes mellitus

AIMS

The influence of socio-economic status on the prevalence of Type 1 and Type 2 diabetes mellitus, and on obesity, was explored using routinely collected healthcare data for the population of Tayside, Scotland.

METHODS

Among 366,849 Tayside residents, 792 and 5,474 patients with Type 1 and Type 2 diabetes, respectively, were identified from a diabetes register. The Carstairs Score was used as a proxy for socio-economic status. This is a material deprivation measure derived from the UK census, using postcode data for four key variables. Odds ratios for diabetes prevalence, adjusted for age, were determined for each of six deprivation categories (1 - least deprived, 6/7 - most deprived). The mean body mass index (BMI) in each group was also determined, and the effect of deprivation category explored by analysis of covariance, adjusting for age and sex.

RESULTS

The prevalence of Type 2 diabetes, but not Type 1 diabetes, varied by deprivation. People in deprivation category 6 and 7 were 1.6-times (95% confidence interval 1.4-1.8) more likely to have Type 2 diabetes than those least deprived. There was no relationship between deprivation and BMI in Type 1 diabetes (P = 0.36), but there was an increase in BMI with increasing deprivation in Type 2 diabetes (P < 0.001; test of linearity P < 0.001).

CONCLUSIONS

The study confirms the relationship between deprivation and the prevalence of Type 2 diabetes. There are more obese, diabetic patients in deprived areas. They require more targeted resources and more primary prevention.

Impact of type 1 and type 2 diabetes on patterns and costs of drug prescribing: a population-based study

OBJECTIVE

Utilization and costs of prescription drugs were investigated in diabetic and nondiabetic patients.

RESEARCH DESIGN AND METHODS

The study was carried out in Tayside, Scotland, U.K. A validated population-based diabetes register was used to identify patients with type 1 and type 2 diabetes, and a database of all prescriptions dispensed in the community was used to investigate drug utilization in 1995.

RESULTS

In a population of 406,526, there were 974 (0.2%) with type 1 diabetes and 6,869 (1.7%) with type 2 diabetes. The mean dispensed prescribing rates for all drugs (excluding antidiabetic medication) were higher across all age-groups for diabetic patients. After adjusting for age, patients with type 1 diabetes were 2.07 times (95% CI 2.03-2.11) more likely and patients with type 2 diabetes were 1.70 times (1.69-1.71) more likely to be dispensed a drug item than people without diabetes. This likelihood was increased in every drug category, even those not directly related to diabetes, and the proportion and cost of drug items dispensed to diabetic patients was therefore higher than expected given the prevalence of diabetes. Upon projecting these results to the U.K. population, it was discovered that nearly 8% of the U.K. drug budget (Pound Sterling 350 million) is accounted for by patients with diabetes (90% of that by patients with type 2 diabetes).

CONCLUSIONS

This study highlights the increased usage and cost of prescription drugs in diabetes, with type 2 diabetes constituting a particular burden. It was discovered that 1.4% of drug usage in the entire population can be accounted for by the increased prescribing rate of diabetic patients compared with that of nondiabetic patients.

High prevalence of primary aldosteronism in the Tayside hypertension clinic population

Primary aldosteronism (PA) was thought to be rare but recent evidence from Australia suggests that it may be more common. As this has important implications in terms of hypertension management, we undertook to screen for this treatable condition in our hypertension clinic. We obtained blood samples in sequential patients referred for assessment in our hypertension clinic in Tayside for plasma renin activity (PRA) and aldosterone. The aldosterone to PRA ratio (ARR) was used as an initial screening test to identify potential patients with PA. Those patients with an elevated ratio (> or =750) were admitted for the salt loading and fludrocortisone suppression test. These patients also underwent adrenal CT scanning, and in selected patients, adrenal scintigraphy. Between May 1995 and January 1997 (21 months), we screened a total of 495 patients. ARR was available in 465 (93.9%) patients. Out of that number, 77 (16. 6%) had an elevated ratio of > or =750, five of whom had an adrenal adenoma (one had previous adrenalectomy). Forty-five of these patients were admitted for the salt loading and fludrocortisone suppression test with 41 positive test results suggesting PA. One patient with a negative salt loading test result however had an adenoma proven on histology. A total of 43 cases of PA were identified, giving a minimum prevalence of 9.2% (43/465). Potentially the prevalence may be up to 15% assuming that the ARR has a sensitivity of 93% (42/45) in predicting PA. In conclusion, about one in 10 patients attending a hypertension clinic may have PA. This suggests that the prevalence of PA in Tayside is as high as that in the Australian hypertensive population, and this is likely to be true elsewhere, with obvious important implications for hypertension management.

Regional variation in incidence and case fatality of myocardial infarction among young women in England, Scotland and Wales

OBJECTIVES

To examine the regional variation in incidence and case fatality of myocardial infarction among young women.

DESIGN

Cross sectional survey, using population based incidence data.

SETTING

England, Scotland and Wales.

SUBJECTS

Subjects were women aged 16-44 with a diagnosis of myocardial infarction between 1 October 1993 and 15 October 1995.

OUTCOME MEASURES

Incidence of myocardial infarction per 100,000 women years, with case fatality as a percentage of total cases.

RESULTS

Incidence of myocardial infarction rose steeply from age 33 upwards, (maximum = 20.2 cases per 100,000 women years at age 44). The adjusted incidence rate for myocardial infarction was 3.7 (95% CI 3.2, 4.2) times greater in Scotland than in southern England. In contrast, case fatality was significantly lower in Scotland: 18.5% (95% CI 13.1%, 25.0%), compared with 31.0% (95% CI 25.9%, 36.0%) in southern England.

CONCLUSIONS

The incidence of myocardial infarction varied widely within the United Kingdom. Case fatality variation may reflect differences in ambulance response, or in diagnostic acumen, within the regions.

Physical activity level is an independent predictor of the diurnal variation in blood pressure

OBJECTIVE

The aim of this study was to define the relationship between physical activity and the magnitude of the percentage fall in blood pressure at night (nocturnal dip).

METHODS

We simultaneously monitored 24-h ambulatory blood pressure and measured physical activity by actigraphy in 434 patients. Blood pressure was measured every 20 min; the actigraph integrated an activity score every 10 s. Mean daytime and night-time activity were calculated from mean scores for the 15 min preceding each blood pressure measurement. Nocturnal dip in systolic and diastolic blood pressure (SBP and DBP) were regressed on mean (log-transformed) daytime activity. Mean night-time activity, age, gender, smoking status, body mass index (BMI) and clinic blood pressure were added into a multiple linear regression.

RESULTS

The patient group was heterogeneous in age, gender and mean 24-h blood pressure. Mean daytime activity level was significantly and positively associated with the magnitude of the nocturnal dip in both SBP and DBP. Increased night-time activity was significantly associated with a smaller nocturnal dip. Older patients had a smaller nocturnal dip per log unit daytime activity. Nocturnal dip in SBP was greater in males, and smaller in those taking antihypertensive medications. Smoking, BMI and clinical blood pressure level were not associated with the extent of the nocturnal dip after adjustment for other factors.

CONCLUSIONS

Daytime and night-time physical activity levels are independently and significantly predictive of the magnitude of the nocturnal dip in blood pressure. Variation in activity may confound interpretation of 24-h ambulatory blood pressure monitoring, and contribute to the poor reproducibility of dipper status.