P1691Impact of dose and duration of dietary salt reduction on blood pressure levels: systematic review and meta-analysis of randomised trials

Background

Authoritative medical and public health agencies in most countries advise to reduce population dietary salt intake to under 5–6 g/day as a strategy for preventing high blood pressure and cardiovascular disease. However, there is still dispute about whether salt reduction should be adopted by all populations. In addition, the effect of duration of dietary salt reduction has not been sufficiently investigated.

Purpose

To understand the effect of dietary salt reduction on blood pressure and the impact of intervention duration.

Methods

A systematic review and meta-analysis was conducted. Randomized controlled trials that allocated participants to low and high salt intake, without confounding from unequal concomitant interventions, were included. We excluded studies done in individuals younger than 18 years, pregnant women, individuals with renal disease or heart failure, and studies with sodium excretion estimated from spot urine. Random effect meta-analysis was used to generate pooled estimates of the effect on 24-hour urinary sodium excretion, systolic and diastolic blood pressure. Multivariate meta-regression was used to quantify the dose response effect of dietary salt on blood pressure change and to understand the impact of the intervention duration.

Results

125 studies were included with 162 data points extracted. Ninety-nine data points (61%) had interventions under 4 weeks. Overall, 24-hour urinary sodium excretion changed by −141 mmol (95% CI: −156; −126), systolic blood pressure changed by −4.4 mm Hg (95% CI: −5.2; −3.7) and diastolic blood pressure changed by −2.4 mm Hg (95% CI: −2.9; −1.9). Sodium reduction resulted in a significant decrease of systolic blood pressure in all subgroups except in participants with low baseline sodium intake (<109 mmol) (Figure 1). Each 100 mmol reduction of sodium was associated with 2.7 mm Hg (95% CI: 1.0; 4.4; p=0.002) reduction of systolic blood pressure and 1.2 mm Hg (95% CI: 0.0; 2.4; p=0.046) reduction of diastolic blood pressure after adjusting for intervention duration, age, sex, race, baseline blood pressure, baseline sodium intake and interaction between age and baseline blood pressure. For the same amount of salt reduction, a 10 mm Hg higher baseline systolic blood pressure would result in 2.5 mm Hg greater reduction of systolic blood pressure. There is not enough evidence to show the impact of intervention duration.

Figure 1

Conclusions

Our meta-analysis showed that sodium reduction could reduce blood pressure in all adult populations regardless of age, sex and race. The effect of salt reduction on systolic blood pressure increases with higher baseline blood pressure. Further studies, designed to investigate the impact of intervention duration, are needed to understand the significance of the duration.

Acknowledgement/Funding

None

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Stroke genomics in people of African ancestry: charting new paths

One in six people worldwide will experience a stroke in his/her lifetime. While people in Africa carry a disproportionately higher burden of poor stroke outcomes, compared to the rest of the world, the exact contribution of genomic factors to this disparity is unknown. Despite noteworthy research into stroke genomics, studies exploring the genetic contribution to stroke among populations of African ancestry in the United States are few. Furthermore, genomics data in populations living in Africa are lacking. The wide genomic variation of African populations offers a unique opportunity to identify genomic variants with causal relationships to stroke across different ethnic groups. The Stroke Investigative Research and Educational Network (SIREN), a component of the Human Health and Heredity in Africa (H3Africa) Consortium, aims to explore genomic and environmental risk factors for stroke in populations of African ancestry in West Africa and the United States. In this article, we review the literature on the genomics of stroke with particular emphasis on populations of African origin.

Magnetic field exposure of commercial airline pilots

PURPOSE: Airline pilots are exposed to magnetic fields generated by the aircraft's electrical and electronic systems. The purpose of this study was to directly measure the flight deck magnetic fields to which commercial airline pilots are exposed when flying on different aircraft types over a 75-hour flight-duty month.METHODS: Magentic field measurements were taken using personal dosimeters capable of measuring magnetic fields in the 40-800 Hz frequency range. Dosimeters were carried by either the Captain or the First Officer on Boeing 737/200, Boeing 747/400, Boeing 767/300ER, and Airbus 320 aircraft. The data were analyzed by aircraft type, with statistics based on block hours. Block hours begin when the aircraft departs the gate prior to take off and end when the aircraft returns to the gate after landing.RESULTS: Approximately 1008 block hours were recorded at a sampling rate of 3 seconds. Total block time exposure to the pilots ranged from a harmonic geometric mean of 6.7 milliGauss (mG) for the Boeing 767/300ER to 12.7 mG for the Boeing 737/200.CONCLUSIONS: Measured flight deck magnetic field levels were substantially above the 0.8 to 1 mG level typically found in the home or office and suggest the need for further study to evaluate potential health effects of long-term exposure.

Disparity between whites and african-americans in knowledge and treatment of cholesterol. Carolina heart survey

PURPOSE: Elevated cholesterol is a known risk factor for coronary heart disease and studies have demonstrated a decrease in myocardial infarctions and strokes in those treated with cholesterol-lowering medications. A statewide survey was conducted to determine knowledge and treatment of cholesterol in South Carolina residents.METHODS: In 1998, a random digit telephone survey was conducted of 1200 adults in South Carolina, including 28.2% African Americans (AA), using a 46-item instrument developed to quantify awareness, knowledge and treatment of cholesterol.RESULTS: Nearly 90% of both AA and Whites (W) believe high cholesterol levels can cause a "heart attack." However, more AA (90.2%) than W (82.8%) believe that high cholesterol levels cause a "stroke" (p = 0.005). Though not statistically significant, 19.5% of W compared to 23.4% of AA reported not ever having their cholesterol checked (p = 0.066). Of those who had their cholesterol checked, less than half (47%) knew their most recent cholesterol or knew a "good" cholesterol level for an adult (41%). Fewer AA could recall their cholesterol level (p = 0.011), or knew a "good" cholesterol level for an adult (p < 0.001) as compared with W. Of the 24.2% who were told they had elevated cholesterol, 59% were under the care of a physician for cholesterol treatment, of which 56.6% reported taking cholesterol-lowering medications. There was a significant difference in the reported treatment with cholesterol-lowering medications between W and AA, 63% versus 33%, respectively (p = 0.006) and ranged from a high of 73.5% in W males to 29.4% in AA females (p = 0.005).CONCLUSIONS: The results of this population assessment suggest less knowledge about cholesterol among AA and racial disparity with regard to treatment with medications of elevated cholesterol levels.

The impact of birth weight on the racial disparity of end-stage renal disease

PURPOSE: Blacks have a high rate of end-stage renal disease (ESRD) and low birthweight (LBW) than whites. LBW has been associated with ESRD. The purpose of this study was to assess impact of LBW on the racial difference in ESRD.METHODS: Patients born in SC after 1950 and diagnosed with ESRD between 1991-1996 were identified from the ESRD registry. Birth weight was compared for 858 black and 372 white patients and 2460 controls matched for age, sex, and race. LBW was defined as birthweight <2500 g.RESULTS: Among patients with ESRD, mean birthweight was lower in blacks than whites (3179 vs 3367 g, p < 0.001). LBW was more common in blacks than whites with ESRD (13.9 vs 7.5%, p = 0.02). The risk ratio for LBW among ESRD patients was 1.4 (95% C.I. 1.1 to 1.8) for blacks and 1.5 (95% C.I. 0.9 to 2.5) for whites. The population attributable risk (PAR) for ESRD due to LBW was greater for blacks than whites (33.6 vs 4.2 per 100,000).CONCLUSIONS: Birthweights were lower and LBW was more common among blacks than whites with ESRD. Moreover, LBW contributed more to the PAR of ESRD in blacks than whites. Thus, LBW may contribute to the greater risk for ESRD in African Americans than Caucasians. This preliminary study indicates that further research on the link between LBW and ESRD could be instructive in understanding the racial health disparities.

Epidemiology of Lung Cancer with Special Reference to Genetics, Bioassays, Women, and Developing Countries

The twentieth century may be looked back upon as the century of lung cancer. At the beginning of the century lung cancer was quite rare, but this century the rates have increased approximately 10-fold and it is the second most common type of cancer and has become the leading cause of death due to cancer in the United States. The rate of lung cancer among U.S. women continues to rise, in contrast rates in U.S. men have been declining since about 1990. Cigarette smoking accounts for 85-90% of lung cancer deaths in the United States. However, only 10-15% of smokers eventually develop lung cancer. In the past 25 years, since the U.S. Surgeon General's ground breaking report in 1964, overall smoking rates have been declining, but smoking still remains a significant behavior. More troubling, the rates of smoking continue to increase in many parts of the world. Advances in molecular biology and early diagnosis have increased the understanding of lung cancer etiology and may be effective in uncovering more efficient detection and treatment regimens. These advances will hopefully make lung cancer as uncommon at the end of the twenty-first century, as it was at the beginning of the twentieth century.

Managing hypertension in the southeastern United States: applying the guidelines from the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI)

The southeastern United States has the highest occurrence of heart disease and stroke and among the highest rates of congestive heart failure and renal failure in the country. The Consortium for Southeastern Hypertension Control (COSEHC) is cooperating with other organizations in implementing initiatives to reduce morbidity and mortality from hypertension-related conditions in the southeastern United States. This article outlines for clinicians special consideration for implementation of the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) in the southeastern United States. Clinicians are encouraged to adapt the recommendations of JNC VI to their own patient groups, paying attention to these specific areas: (1) Ensure screening for hypertension in your practice and community. (2) Evaluate all patients for accompanying risk factors and target organ damage. (3) Promote lifestyle management for individual patients and populations for prevention and treatment of hypertension. (4) Set a goal blood pressure for each patient, and monitor progress toward that goal. (5) Recognize that many patients will be candidates for blood pressure goals of <130/85 mm Hg. (6) Pay attention to compelling and special indications such as diabetes, congestive heart failure, and renal dysfunction. (7) Consider combination therapy. (8) Maximize staff contributions to enhance patient adherence. (9) Encourage patient, family, and community activities to promote healthy lifestyles and blood pressure control.

Leukaemia in the vicinity of two tritium-releasing nuclear facilities: a comparison of the Kruemmel Site, Germany, and the Savannah River Site, South Carolina, USA

In 1991, an increased rate of childhood leukaemia was reported from the small northern German community of Elbmarsch, which is located on the banks of the River Elbe opposite the Kruemmel nuclear power plant. Owing to the fact that the increase occurred six years after the start-up of the plant, radioactive discharges were suspected as being implicated in the development of the cases. Previous investigations have failed to identify any exposure which might be associated with the cluster. Nonetheless, concern regarding the increased tritium burden in the environment remains. To further assess the impact of tritium releases to the environment upon population cancer rates, the releases and leukaemia rates at the Savannah River site, USA, were compared with the Kruemmel site. Based on the data from 1991 to 1995, the incidence of childhood leukaemia in the vicinity of the Savannah River site was non-significantly less than expected compared with the significantly higher than expected rates close to the German plant. In contrast, tritium releases from the Savannah River site exceed those from the Kruemmel site by several orders of magnitude. The results of this observational study suggest that factors other than environmental tritium releases are associated with the increased number of leukaemia cases near the Kruemmel site.

Overview of the Diabetes Initiative of South Carolina

Implementation is underway for many of these programs, and there are descriptions of activities elsewhere in this symposium. The Board recognizes that in dealing with the complications of a chronic disease like diabetes, many years of intense effort will be needed before significant results may be appreciated. Progress will be monitored regularly by the Surveillance Council and SCDCP/DHEC, and modifications of the plan will be made by the Board at intervals after review of the data. We are optimistic that over the next decade, this system will make a significant impact to reduce mortality, morbidity, and costs of diabetes, and the result will be an increased quality of life for people affected by diabetes in South Carolina.

Specialists achieve better outcomes than generalists for lung cancer surgery

OBJECTIVE

A push toward care provided by generalists as opposed to specialists has occurred in the health-care marketplace despite a lack of provider specific outcome data. The objective of this study was to determine whether the outcome of patients undergoing lung cancer surgery is different between general surgeons (GSs) and thoracic surgeons (TSs).

DESIGN

Examination of data from a state-wide severity-adjusted administrative hospital discharge database.

SETTING/PARTICIPANTS

Patients undergoing lung cancer resection in all nonfederal acute care hospitals within South Carolina.

MAIN OUTCOME MEASURES

Mortality by specialty adjusted for case mix.

RESULTS

From 1991 to 1995, 1,720 resections for lung cancer were performed in South Carolina. One hundred thirty-seven cases were excluded because surgeons did not meet the predefined criteria for board certification, leaving 1,583 resections for analysis. One-half of lobectomies and nearly 60% of pneumonectomies were performed by GSs. Patients were similar in age, sex, gender, race, and the proportion in each severity of illness subclass. Mortality was significantly higher in patients who underwent lobectomy by GSs vs TSs (5.3% vs 3.0%; p<0.05) and in patients with extreme comorbidities (43.6% vs 25.4%; p=0.03) or age >65 years (7.4% vs 3.5%; p<0.05). Seventy percent of TSs performed > 10 cases in the series, whereas 75% of GSs performed <10 (p=0.05). Logistic regression analysis failed to identify any significant variable that might explain the mortality differences between TSs and GSs.

CONCLUSION

Mortality is lower for lung cancer resection when the surgery is performed by a TS.

An evaluation of the safety and efficacy of fluconazole in the treatment of onychomycosis

Sixteen subjects were enrolled in this open-label noncomparative study to evaluate the safety and efficacy of fluconazole as a single daily dose for a period of 6 months. Liver function enzymes were monitored to assess safety. An adverse function questionnaire was used on a monthly basis to assess patient tolerance. A visual analogue scale was used to assess efficacy of treatment. After 6 months of fluconazole, all subjects experienced improvement in the appearance of their nails. None of the subjects evidenced any elevation in liver function enzymes. Adverse reactions were limited and consistent with other studies involving fluconazole. Fluconazole proved to be safe and efficacious in the treatment of onychomycosis. Further studies are needed to determine a cost-effective dosing regimen for the treatment of onychomycosis with fluconazole.