Effectiveness of interventions to improve the detection and treatment of osteoporosis in primary care settings: a systematic review and meta-analysis

This study aims to evaluate the effectiveness of primary care interventions to improve the detection and treatment of osteoporosis. Eight electronic databases and six gray literature sources were searched. Randomized controlled trials, controlled clinical trials, quasi-randomized trials, controlled before-after studies, and interrupted time series written in English or French from 1985 to 2009 were considered. Eligible studies had to include patients at risk (women ≥ 65 years, men ≥ 70 years, and men/women ≥ 50 years with at least one major risk factor for osteoporosis) or at high risk (men/women using oral glucocorticoids or with previous fragility fractures) for osteoporosis and fractures. Outcomes included bone mineral density (BMD) testing, osteoporosis treatment initiation, and fractures. Data were pooled using a random effects model when applicable. Thirteen studies were included. The majority were multifaceted and involved patient educational material, physician notification, and/or physician education. Absolute differences in the incidence of BMD testing ranged from 22% to 51% for high-risk patients only and from 4% to 18% for both at-risk and high-risk patients. Absolute differences in the incidence of osteoporosis treatment initiation ranged from 18% to 29% for high-risk patients only and from 2% to 4% for at-risk and high-risk patients. Pooling the results of six trials showed an increased incidence of osteoporosis treatment initiation (risk difference (RD) = 20%; 95% CI: 7-33%) and of BMD testing and/or osteoporosis treatment initiation (RD = 40%; 95% CI: 32-48%) for high-risk patients following intervention. Multifaceted interventions targeting high-risk patients and their primary care providers may improve the management of osteoporosis, but improvements are often clinically modest.

Exposure to anti-infective drugs during pregnancy and the risk of small-for-gestational-age newborns: a case-control study

OBJECTIVE

To determine the association between anti-infective exposure during the last two trimesters of pregnancy and the risk of small-for-gestational-age (SGA) newborns.

DESIGN

Case-control study within the Québec Pregnancy Registry.

SETTING

Province of Québec, Canada.

SAMPLE

Analyses were performed on prospectively collected data of 63,338 pregnant women that met eligibility criteria for the study (8192 cases and 55,146 controls).

METHODS

Unconditional logistic regression models were used to quantify the association between exposure to anti-infective drugs and the risk of SGA.

MAIN OUTCOME MEASURES

A case of SGA was defined as a pregnancy resulting in a baby that weighs below the tenth percentile, adjusted for gestational age and gender, according to the Canadian gender-specific reference curves. A control was defined as a pregnancy resulting in a baby that weighs greater or equal to the tenth percentile, adjusted for gestational age and gender.

RESULTS

Exposure to all combined anti-infective drugs was not associated with the risk of SGA (OR 0.97; 95% CI 0.91-1.04). The use of sulfamethoxazole/trimethoprim was associated with SGA (OR 1.61; 95% CI 1.16-2.23), whereas the use of urinary anti-infective drugs decreased the risk (OR 0.80; 95% CI 0.65-0.97).

CONCLUSIONS

Exposure to sulfamethoxazole/trimethoprim during the last two trimesters of pregnancy was associated with SGA. Further research is needed to address the use of other therapeutic alternatives in the management of infections that predispose infants being born SGA in pregnant women with other risk factors for this condition.

Impact of a primary care physician workshop on osteoporosis medical practices

SUMMARY

Attendance at a fragility-fractures-prevention workshop by primary care physicians was associated with higher rates of osteoporosis screening and treatment initiation in elderly female patients and higher rates of treatment initiation in high-risk male and female patients. However, osteoporosis management remained sub-optimal, particularly in men.

INTRODUCTION

Rates of osteoporosis-related medical practices of primary care physicians exposed to a fragility-fractures-prevention workshop were compared with those of unexposed physicians.

METHODS

In a cluster cohort study, 26 physicians exposed to a workshop were matched with 260 unexposed physicians by sex and year of graduation. For each physician, rates of bone mineral density (BMD) testing and osteoporosis treatment initiation among his/her elderly patients 1 year following the workshop were computed. Rates were compared using multilevel logistic regression models controlling for potential patient- and physician-level confounders.

RESULTS

Twenty-five exposed physicians (1,124 patients) and 209 unexposed physicians (9,663 patients) followed at least one eligible patient. In women, followed by exposed physicians, higher rates of BMD testing [8.5% versus 4.2%, adjusted OR (aOR) = 2.81, 95% CI 1.60-4.94] and treatment initiation with bone-specific drugs (BSDs; 4.8% vs. 2.4%, aOR = 1.95, 1.06-3.60) were observed. In men, no differences were detected. In patients on long-term glucocorticoid therapy or with a previous osteoporotic fracture, higher rates of treatment initiation with BSDs were observed in women (12.0% vs. 1.9%, aOR = 7.38, 1.55-35.26), and men were more likely to initiate calcium/vitamin D (5.3% vs. 0.8%, aOR = 7.14, 1.16-44.06).

CONCLUSIONS

Attendance at a primary care physician workshop was associated with higher rates of osteoporosis medical practices for elderly women and high-risk men and women. However, osteoporosis detection and treatment remained sub-optimal, particularly in men.

Control and severity of asthma during pregnancy are associated with asthma incidence in offspring: two-stage case-control study

The extent to which childhood asthma incidence is influenced by asthma control and severity during pregnancy is unknown. We have studied this association during the child's first 10 yrs of life. A two-stage, case-control study, nested in a cohort of 8,226 children of asthmatic mothers, was conducted using three interlinked databases of Quebec, Canada, and mailed questionnaires. A total of 2,681 asthmatic children and 30,318 age-matched controls were selected (< or =20 controls.case(-1); stage 1), and 3,254 selected mothers were mailed questionnaires to obtain additional information (stage 2). Asthma control and severity was defined using validated indexes and childhood asthma incidence based on at least one asthma-related diagnosis and prescription received within 2 yrs. A total of 44 confounders were considered. Compared with children of mild controlled asthmatic mothers, children whose mothers had moderate-to-severe uncontrolled asthma during pregnancy had an increased risk of asthma (adjusted OR 1.27, 95% CI 1.06-1.52). No increased risk was observed for children of mild uncontrolled and moderate-to-severe controlled mothers. Based on one of the largest studies of children of asthmatic mothers, a significant increase in asthma risk was demonstrated among children whose mothers had poor control and increased severity of asthma during pregnancy, indicating that this element should be added to the expanding list of determinants of childhood asthma. As it constitutes a risk factor where pregnant asthmatic females can intervene, it is of great importance for physicians to optimally treat asthmatic females during pregnancy and to encourage females to be adherent to the prescribed asthma medications.

Comparison of direct health care costs related to the pharmacological treatment of osteoporosis and to the management of osteoporotic fractures among compliant and noncompliant users of alendronate and risedronate: a population-based study

This population-based study aimed to compare direct health care costs related to the pharmacological treatment of osteoporosis and to the management of osteoporotic fractures among compliant and noncompliant users of alendronate and risedronate. During a 2-year follow-up period, compared to those with medication possession ratio (MPR) > or = 80%, women with MPR < 80% incurred significantly higher physician care costs and hospital care costs.

INTRODUCTION

This study aimed to compare direct health care costs related to the treatment of osteoporosis and osteoporotic fractures among compliant and noncompliant users of alendronate and risedronate.

METHODS

A cohort of 15,027 women having initiated alendronate or risedronate was identified. MPR and direct health care costs (physician care, hospital care, drugs) were assessed during a 2-year period. Regression models were used to estimate mean predicted cost for compliant (MPR > or = 80%) and noncompliant (MPR < 80%) women.

RESULTS

Mean predicted physician care cost (in Canadian dollars) was $51 among women with MPR < 80% and $34 among those with MPR > or = 80%: mean difference $17, 95% confidence interval (CI) $2-22. Mean predicted hospital care cost was $568 among women with MPR < 80% and $379 among those with MPR > or = 80%: mean difference $189, 95% CI $56-320. Mean predicted drug cost was $439 among women with MPR < 80% and $1,068 among those with MPR > or = 80%: mean difference $-639, 95% CI $-649 to -629.

CONCLUSION

Compared to compliant women, noncompliant women incurred significantly higher physician care and hospital care costs. Due to lower drug costs, total direct health care costs were lower among noncompliant women.

Better adherence to antihypertensive agents and risk reduction of chronic heart failure

AIMS

Antihypertensive (AH) agents have been shown to reduce the risk of major cardiovascular events including chronic heart failure (CHF). However, the impact of changes in patterns of AH agents use on CHF is unknown. Our objective was to estimate to which different patterns of AH agent use is associated with the occurrence of CHF in a population-based study.

METHOD AND RESULTS

A cohort of 82 320 patients was reconstructed using the Régie de l'assurance maladie du Québec's databases. Patients were eligible if they were between 45 to 85 years of age, had no indication of cardiovascular disease and were newly treated with AH therapy between 1999 and 2004. A nested case-control design was used to study the occurrence of CHF. Every case of CHF was matched for age and duration of follow-up to a maximum of 15 randomly selected controls. Adherence level was reported as a medication possession ratio. Conditional logistic regression models were used to estimate the rate ratio (RR) of CHF adjusting for different covariables. The mean patient age was 65 years, 37% were male, 8% had diabetes, 19% had dyslipidaemia and mean time of follow-up at 2.7 years. High adherence level (95%) to AH therapy compared with lower adherence level (60%) was associated with an additional reduction of CHF events (RR: 0.89; 0.80-0.99). Risk factors for CHF were being on social assistance, diabetes, dyslipidaemia, higher chronic disease score and developing a cardiovascular condition during follow-up.

CONCLUSION

Our study suggests that a better adherence is associated with a significant risk reduction of CHF. Adherence to AH therapy needs to be improved to optimize benefits.

Persistence and determinants of statin therapy among middle-aged patients for primary and secondary prevention

AIMS

Statins have been shown to significantly reduce morbidity and mortality in patients with coronary artery disease (CAD), and also in patients with dyslipidaemia when statins are taken regularly. Middle-aged patients have the highest level of forecasting benefit and little is known about persistence rate of these therapies in a real-life setting. The objective was to evaluate the persistence rate of middle-aged patients initiating a statin therapy and its relation with several determinants for primary and secondary prevention.

METHODS

A cohort was reconstructed using the RAMQ databases. All patients aged 50-64 years-old who received at least one statin prescription between 1 January, 1998 and 31 December, 2000 for a new intention of treatment for dyslipidaemia were included in the cohort and followed up until 30 June, 2001. The date of the first prescription of statin was defined as the index date. There were 4316 patients in the secondary prevention (CAD diagnosis) and 13,642 patients in primary prevention cohort. The cumulative persistence rate was estimated using Kaplan-Meier, and Cox regression models were used to estimate the hazard ratio of ceasing statins.

RESULTS

We found that persistence with statins had fallen to 71% after 6 months of treatment, and had declined to 45% after 3 years in the secondary prevention cohort; the corresponding figures were 65% and 35% in the primary prevention cohort. Our results suggest that patients with dyslipidaemia in primary prevention compared with those in secondary prevention (HR: 1.18; 1.11-1.25) are less likely to be persistent. Patients with other cardiovascular risk factors such as age (HR: 0.99; 0.98-0.99), diabetes (HR: 0.84; 0.79-0.90), hypertension (HR: 0.76; 0.72-0.80) were most likely to be persistent with statins. We observed lower persistence in patients who have used the greatest number of pharmacies and prescribing physicians.

CONCLUSION

This analysis indicates that barriers to persistence occur early in the therapeutic course. Overall persistence with statins is low, and particularly among patients with few other cardiovascular risk factors.

Pharmacokinetics of morphine and its glucuronidated metabolites in burn injuries

OBJECTIVE

To investigate the effects of major thermal burn injury and continuous intravenous morphine infusion on the disposition of morphine and its glucuronidated metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) once a week for three weeks.

CASE SUMMARIES

Five patients with major first-, second-, or third-degree burn injuries received long-term intravenous morphine infusion. The required dose varied greatly (from 4 to 39.5 mg/h). The steady-state concentrations of morphine, M3G, and M6G ranged from 20 to 452, 29 to 3436, and 20 to 1240 mumol/L, respectively. The systemic clearance (Cls) of morphine ranged from 14.8 to 40.3 mL/min/kg and did not change over time. The ratios of M6G and M3G to morphine were not affected by dose, even with the wide variation of intravenous dosage. Morphine kinetics appeared to be first-order. Mean recovery of morphine, M3G, and M6G in urine was 1.7 +/- 1.0%, 42.0 +/- 16.8%, and 11.8 +/- 3.2%, respectively, and renal clearance ranged from 8 to 64, 26 to 325, and 59 to 589 mL/min, respectively. Mean pain intensity ratings at rest remained low and stable (0.7 +/- 0.9 on day 7, 0.4 +/- 0.3 on day 14, 0 +/- 0 on day 21).

DISCUSSION

To our knowledge, this is the first published report describing morphine, M3G, and M6G disposition in patients with major thermal burn injury. The Cls of morphine is similar to that observed in other patient populations and healthy subjects, suggesting that the presence of major burn injuries or a continuous morphine infusion over a three-week period may not contribute significantly to the variability among individuals. In these cases, the renal clearance of morphine and its glucuronides was within the range of values reported for other populations of patients and healthy subjects. Recovery of morphine and its glucuronides in urine was also similar to that in healthy individuals.

CONCLUSIONS

These cases suggest that the effects of major burn injuries and of long-term intravenous infusion of morphine did not seem to modify morphine, M3G, and M6G disposition. Among patients with burn injuries, the severity of burns of duration of administration are not a cause of nonlinear kinetic of morphine or of morphine resistance. The morphine infusion rate was substantially variable and not directly related to its clearance, suggesting that monitoring of morphine should be focused on the clinical response.

Efficacy and cost of HMG-CoA reductase inhibitors in the treatment of patients with primary hyperlipidemia

BACKGROUND

Screening for hyperlipidemia is a substantial cost burden, as is its treatment. The choice of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and the dose level may have significant implications for both efficient and cost effective therapy.

OBJECTIVE

To compare the efficiency and cost of statins.

MATERIALS AND METHODS

A meta-analysis was conducted of randomized, controlled trials of monotherapy with fixed doses of statins published in the literature until June 1998. Two authors independently extracted data from 49 trials comprising 14,130 patients. The percentage reduction (95% confidence intervals) of low density lipoprotein (LDL) cholesterol levels was calculated using a random-effects model. Cost efficiency was defined as the percentage decline of LDL cholesterol per dollar of drug cost.

RESULTS

The population evaluated had a mean baseline LDL cholesterol concentration of 5.31 mmol/L, a mean age of 53.5 years and a mean 59% proportion of males. In reducing LDL cholesterol concentrations to less than 25% of the baseline concentration, a significantly higher cost efficiency was achieved with simvastatin 2.5 mg (-53.3%/dollar). By targeting a reduction between 25% and 29%, significantly higher cost efficiencies were found with simvastatin 5 mg (-28.9%/dollar), cerivastatin 0.2 mg (-23.8%/dollar) and fluvastatin 40 mg (-23.3%/dollar). For reductions in LDL cholesterol concentrations of 30% to 34%, statistically higher cost efficiencies were achieved with simvastatin 20 mg (-15.0%/dollar) and pravastatin 40 mg (-14. 4%/dollar). Finally, atorvastatin 10 mg yielded a value of -22. 9%/dollar for a 36% reduction in LDL cholesterol concentration.

CONCLUSIONS

At current prices of the various doses of statins, the cost efficiency of standard and more aggressive therapies varies substantially. In the context of health care budgets, targeting at-risk patients and using statins judiciously should facilitate the efforts of clinicians and patients to reduce lipid profiles optimally and decrease the cost burden.

Savings in direct medical costs from the use of tobramycin solution for inhalation in patients with cystic fibrosis

OBJECTIVE

Two identical 24-week, double-blind, placebo-controlled trials of tobramycin solution for inhalation (TOBI [PathoGenesis Corporation, Seattle, Washington]) in cystic fibrosis patients with chronic Pseudomonas aeruginosa infection were conducted in the United States. The aim of the present study was to extrapolate the US trial data to a Canadian setting, using Canadian costs to estimate the savings in direct medical costs that might result from use of a similar 24-week TOBI regimen versus usual care in 2 Canadian provinces.

BACKGROUND

Cystic fibrosis is a genetic disease in which persistent respiratory infection, usually due to P. aeruginosa infection, is the major cause of morbidity and mortality.

METHODS

The US trials demonstrated that TOBI produced significant improvements in pulmonary function test results, reduced sputum levels of P. aeruginosa, and resulted in a 26% reduction in the probability of hospitalization (95% CI, 2%-43% vs placebo in the clinical trials). Individual patient data from the US trials were used to calculate the mean number of days in hospital as well as the mean number of days of home intravenous or oral antibiotic therapy. To adjust for Canadian pricing, pertinent economic data were obtained from Statistics Canada and the Ontario and Quebec health ministries. Demographic and baseline data were obtained from health surveys conducted by the Canadian Cystic Fibrosis Foundation.

RESULTS

Economic analysis showed that the use of TOBI for 24 weeks would result in estimated mean per-patient savings in direct medical costs (in Canadian dollars) of $4055 in Ontario and $4916 in Quebec, which would substantially offset the Canadian acquisition price of $8602 for the same 24-week period.

CONCLUSIONS

Assuming that the percentage of reduction in hospital days observed in the US trials would also occur in the Canadian clinical setting, use of TOBI would reduce the use of health care services, particularly hospital days, and lead to substantial savings in direct medical costs that would offset its acquisition price. Whether this reduction actually occurs after TOBI enters the Canadian market is a subject for future investigation.

Impact of treating hyperlipidemia or hypertension to reduce the risk of death from coronary artery disease

OBJECTIVE

To compare the prevalence of modifiable risk factors for cardiovascular disease among hypertensive and nonhypertensive adults and to estimate the effect of treating hyperlipidemia or hypertension to reduce the risk of death from coronary artery disease.

METHODS

The authors evaluated a sample of 7814 subjects aged 35-74 years free of clinical cardiovascular disease from the Canadian Heart Health Surveys to estimate the prevalence of cardiovascular risk factors. They identified hyperlipidemic subjects (ratio of total cholesterol to high-density lipoprotein cholesterol [total-C/HDL-C] 6.0 [corrected] or more for men and 5.0 [corrected] or more for women) and hypertensive subjects (systolic or diastolic blood pressure 160/90 mm Hg or greater, or receiving pharmacologic or nonpharmacologic treatment). A life expectancy model was used to estimate the rate of death from coronary artery disease following specific treatments.

RESULTS

An elevated total-C/HDL-C ratio was significantly more common among hypertensive than nonhypertensive men aged 35-64 (rate ratio [RR] 1.56 for age 35-54, 1.28 for age 55-64) and among hypertensive than nonhypertensive women of all ages (RR 2.73 for age 35-54, 1.58 for age 55-64, 1.31 for age 65-74). Obesity and a sedentary lifestyle were also more common among hypertensive than among nonhypertensive subjects. According to the model, more deaths from coronary artery disease could be prevented among subjects with treated but uncontrolled hypertension by modifying lipids rather than by further reducing blood pressure for men aged 35-54 (reduction of 50 v. 29 deaths per 100,000) and 55-64 (reduction of 171 v. 104 deaths per 100,000) and for women aged 35-54 (reduction of 44 v. 39 deaths per 100,000). Starting antihypertensive therapy in subjects aged 35-74 with untreated hypertension would achieve a greater net reduction in deaths from coronary artery disease than would lipid lowering. Nonetheless, the benefits of lipid therapy were substantial: lipid intervention among hypertensive subjects aged 35-74 represented 36% of the total benefits of treating hyperlipidemia in the total hyperlipidemic population.

INTERPRETATION

The clustering of hyperlipidemia and the potential benefits of treatment among hypertensive adults demonstrate the need for screening and treating other cardiovascular risk factors beyond simply controlling blood pressure.

Efficacy and costs of patient-controlled analgesia versus regularly administered intramuscular opioid therapy

BACKGROUND

Many studies have shown the efficacy of patient-controlled analgesia (PCA). However, it is not clear whether PCA has clinical or economic benefits in addition to efficient analgesia. The current study was designed to evaluate these issues by comparing PCA with regularly administered intramuscular injections of opioids after hysterectomy.

METHODS

This prospective study included 126 patients who underwent abdominal hysterectomy and were randomly assigned to receive PCA or regularly timed intramuscular injections of morphine during a period of 48 h. Doses were adjusted to provide satisfactory analgesia in both treatment groups. Pain at rest and with movement, functional recovery, drug side effects, and patient satisfaction were measured using rating scales and questionnaires. The costs of PCA and intramuscular therapy were calculated based on personnel time and drug and material requirements.

RESULTS

Comparable analgesia was observed with the two treatment methods, with no significant differences in the incidence of side effects or patient satisfaction. The medication dosage had to be adjusted significantly more frequently in the intramuscular group than in the PCA patients. The PCA did not favor a faster recuperation time compared with intramuscular therapy in terms of times to ambulation, resumption of liquid and solid diet, passage of bowel gas, or hospital discharge. The results of the economic evaluation, which used a cost-minimization model and sensitivity analyses, showed that PCA was more costly than regular intramuscular injections despite the fact that no costs for the pump were included in the analyses. Cost differences in nursing time favoring PCA were offset by drug and material costs associated with this type of treatment.

CONCLUSIONS

Compared with regularly scheduled intramuscular dosing, PCA is more costly and does not have clinical advantages for pain management after hysterectomy. Because of the comparable outcomes, the general use of PCA in similar patients should be questioned.

Smoking cigarettes is associated with increased sperm disomy in teenage men

OBJECTIVE

To determine whether moderate cigarette smoking and alcohol consumption in teenage men is associated with increases in disomic sperm and detectable changes in semen quality.

DESIGN

Cohort study.

SETTING

Military recruiting station, Teplice, Czech Republic.

PATIENT(S)

Ten current smokers (20 cigarettes per day for at least 2 years, exposure confirmed by urine cotinine) who also consumed alcohol and 15 nonsmokers. All patients were exactly 18 years old, healthy, and of unproven fertility.

MAIN OUTCOME MEASURE(S)

Sperm aneuploidy by multicolor fluorescence in situ hybridization for chromosomes 8, X, and Y; conventional semen analyses; computer-aided sperm analysis for motility; and sperm chromatin structure analysis.

RESULTS

Smokers showed elevated frequencies of sperm aneuploidy (Y disomy, P <0.001; aggregate of X, Y, and 8 disomies, P <0.01); reduced linearity of sperm motion (P <0.05); and more "round-headed" sperm (P <0.01). Smokers' semen contained fewer sperm (P <0.001) and fewer motile sperm (P <0.02), which was attributable, in part, to shorter abstinence intervals among smokers (P <0.02).

CONCLUSION(S)

Cigarette smoking among teenagers was associated with increases in disomic sperm and a diminution in specific aspects of semen quality. Such defects may affect male fertility and may increase future chances of fathering offspring with aneuploidy syndromes.

Treating hyperlipidemia for the primary prevention of coronary disease. Are higher dosages of lovastatin cost-effective?

OBJECTIVE

To compare the average and marginal life-time cost-effectiveness of increasing dosages of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, such as lovastatin, for the primary prevention of coronary heart disease (CHD).

METHODS

We estimated the lifelong costs and benefits of the modification of lipid levels achieved with lovastatin based on published studies and a validated CHD prevention computer model. Patients were middle-aged men and women without CHD, with mean total serum cholesterol levels of 6.67, 7.84, and 9.90 mmol/L (258, 303, and 383 mg/dL), and high-density lipoprotein cholesterol levels of 1.19 mmol/L (46 mg/dL), as described in clinical trials. We estimated the cost per year of life saved for dosages of lovastatin ranging from 20 to 80 mg/d that reduced the total cholesterol level between 17% and 34%, and increased high-density lipoprotein cholesterol level between 4% and 13%.

RESULTS

After discounting benefits and costs by 5% annually, the average cost-effectiveness of lovastatin, 20 mg/d, ranged from $11,040 to $52,463 for men and women. The marginal cost-effectiveness of 40 mg/d vs 20 mg/d remained in this range ($25,711 to $60,778) only for persons with baseline total cholesterol levels of 7.84 mmol/L (303 mg/dL) or higher. However, the marginal cost-effectiveness of lovastatin, 80 mg/d vs 40 mg/d, was prohibitively expensive ($99,233 to $716,433 per year of life saved) for men and women, irrespective of the baseline total cholesterol level.

CONCLUSIONS

Assuming that $50,000 per year of life saved is an acceptable cost-effectiveness ratio, treatment with lovastatin at a dosage of 20 mg/d is cost-effective for middle-aged men and women with baseline total cholesterol levels of 6.67 mmol/L (258 mg/dL) or higher. At current drug prices, treatment with 40 mg/d is also cost-effective for total cholesterol levels of 7.84 mmol/L (303 mg/dL) or higher. However, treatment with 80 mg/d is not cost-effective for primary prevention of CHD.

A head-to-head comparison of the cost effectiveness of HMG-CoA reductase inhibitors and fibrates in different types of primary hyperlipidemia

The objective of this study was to compare the lifetime cost-effectiveness of HMG-CoA reductase inhibitors and fibrates for the treatment of hyperlipidemia. Estimates of lipid modification achieved due to drug therapy were based on published head-to-head comparisons of specific HMG-CoA reductase inhibitors and fibrates in randomized, double-blind studies. We used a validated coronary heart disease (CHD) prevention computer model to estimate the costs and benefits of lifelong lipid modification. The patients were middle-aged men and women who were free of CHD, with either primary type IIa or IIb hyperlipidemia. The intervention used were specific HMG-CoA reductase inhibitors and fibrates at several dosages, which reduced total cholesterol 11-34% and increased high-density lipoprotein cholesterol 1-29%. The main outcome measure was the cost per year of life saved after discounting benefits and costs by 5% annually. The lifetime cost effectiveness of HMG-CoA reductase inhibitors (fluvastatin, lovastatin, pravastatin, simvastatin) and fibrates (bezafibrate, fenofibrate, gemfibrozil) for the treatment of primary hyperlipidemia varied according to patient population, the effectiveness of each drug in modifying lipid levels, and the price of each drug. The estimates of cost per year of life saved for HMG-CoA reductase inhibitors range from $19,886 to $73,632, and $16,955 to $59,488 for fibrates according to gender and type of primary hyperlipidemia. Fluvastatin 20 mg/day was significantly more cost effective than gemfibrozil 1200 mg/day for male patients with type IIa hyperlipidemia. Simvastatin 17.3 mg/day or 20 mg/day yielded similar cost-effectiveness ratios compared with fibrates among type II hyperlipidemic patients. However, micronized fenofibrate was more cost effective than simvastatin 20 mg/day among type IIb patients. The cost effectiveness of lipid therapy varies widely and can be maximized by selecting specific drugs for specific lipid abnormalities.

Breeding dispersions and site fidelity of American redstarts (Setophaga ruticilla)

We relate features of the breeding dispersions and site fidelity of American redstarts (Setophaga ruticilla) to breeding success and interpret the findings in terms of sexual selection. One-year-old male redstarts show delayed plumage maturation, making male dispersions particularly easy to appreciate. In our study site in New Brunswick, Canada, older males usually arrived early each breeding season and gathered in contiguous territories or neighborhoods, while subadult males arrived later and settled peripherally to the adults. Subadult males constituted about 40% of the male population, on average, yet only 5% of banded nestlings returned to the natal breeding ground. Also, newly adult males, 2 years old or more, constituted about 15% of all males. Nearly 50% of adult males returned, twice the return rate of subadults. Among returns, older males returned more often to the same territory than did those that were subadult the previous year. Regardless of age, returns of males in a subsequent year were predicted more by the duration of their stay on the breeding territory than reproductive success. Males outnumbered females. Females returned less often than their mates, but more often if they had fledged young. Females rarely returned to the same mate or territory, but often returned to the same vicinity. The subadult males seem to represent a special dispersive phase of the life history. The evidence indicates strong competition among males for territories and females, older males being more often successful in both circumstances.

Influence of hypoxia and hypercapnia on the kinetics and hypokaliaemic effect of salbutamol in the rabbit

1. The aims were to document the influence of moderate hypoxia or hypercapnia on salbutamol kinetics and its hypokaliaemic effect, following its administration through the intravenous (60 micrograms/kg), intratracheal (60 micrograms/kg), and oral (2400 micrograms/kg) routes (n = 5). In control animals, PaO2 was around 85 mmHg and PaCO2 20 mmHg; in hypoxic animals PaO2 was around 40 mmHg and in the hypercapnic rabbit PaCO2 was 50 mmHg. 2. Following the intravenous administration of salbutamol, the apparent volume of distribution increased two-fold (p < 0.05) in animals with hypoxia and hypercapnia. Consequently, its half life was enhanced (p < 0.05). Given via the trachea, salbutamol bioavailability was decreased by hypoxia. 3. When salbutamol was given orally, hypoxia or hypercapnia increased the area under salbutamol plasma concentration as a function of time (p < 0.05). 4. In control animals, the salbutamol hypokaliaemic effect was greater when administered orally than through the other routes. Compared with control animals, the experimental conditions reduced the hypokaliaemic effect of salbutamol only when given orally. 5. It is concluded that salbutamol kinetics and dynamics can be altered by hypoxia and hypercapnia.

Influence of chronic hypoxia on salbutamol tissular concentrations and on respiratory resistance in anesthetized rabbits

Salbutamol is a potent beta 2-adrenoceptor agonist given to patients with bronchial asthma who are frequently hypoxemic. The aims of this study were to document the influence of chronic hypoxia on salbutamol tissue concentrations and on salbutamol effect on total respiratory resistance. To this purpose, salbutamol (60 micrograms/kg) was administered intravenously to four groups of six rabbits exposed to four experimental conditions: (1) control rabbits breathing air, (2) histamine-induced bronchoconstriction in rabbits breathing air, (3) animals with chronic hypoxia, (4) histamine-induced bronchoconstriction in animals with chronic hypoxia. The area under salbutamol plasma concentration time curve (0 to 45 min) was not affected by these experimental conditions. Compared with control rabbits breathing air, following histamine-induced bronchoconstriction, salbutamol concentrations rose by 40 to 50% in lung and heart (p < 0.05). Hypoxia did not affect salbutamol distribution in these organs; however, in hypoxic animals, histamine-induced bronchoconstriction increased salbutamol concentrations only in the heart (p < 0.05), without affecting those in the lung. Compared with rabbits breathing air and with histamine-induced bronchoconstriction, the effect of salbutamol was reduced in rabbits under chronic hypoxia and histamine-induced bronchoconstriction (p < 0.05). We conclude that chronic hypoxia reduces salbutamol effect on pulmonary resistance, possibly by decreasing salbutamol lung concentrations.

Hepatic and extrahepatic metabolism of salbutamol in anesthetized rabbits

Orally administered salbutamol undergoes an extensive first-pass effect. This study investigated the roles of the intestine (INT), liver (HEP), and lung (LUN) in salbutamol extraction. Salbutamol was administered to five groups of anesthetized rabbits by the following routes: intraduodenal (ID) (800 micrograms/kg), intraportal (IP), (60 micrograms/kg), intrajugular (IV) (60 micrograms/kg), endotracheal (ET) (60 micrograms/kg), and intraarterial (IA) (60 micrograms/kg). Multiple blood samples were drawn and the areas under salbutamol plasma concentrations-time curves (AUCs) were calculated. Since IA salbutamol administration generated 100% bioavailability (F), AUCIA was used as a reference for comparison. Salbutamol F values for the ID, IP, IV, and ET routes were 0.013, 0.15, 0.53, and 0.53, respectively. The ratio of the AUC of salbutamol administered before the organ (ID, IP, IV, or ET) to the AUC estimated when given after the organ (IP, IV, and IA) allowed assessment of the extraction ratio (E) of INT, HEP, and LUN, respectively. EINT was 0.92, EHEP was 0.71, and ELUN was 0.47. The mean ratio of the AUC of the metabolite (AUCM) over the AUC of the parent compound was 704 +/- 77 for the ID, compared with 83 +/- 12 for the IP, 11 +/- 1 for the IV, 1.7 +/- 0.3 for the ET routes, and 4 +/- 1 for the IA routes. On the other hand, when the AUCM was normalized by the dose, this ratio was INT = HEP > LUN, suggesting that the ability of INT to conjugate salbutamol is not very important.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of flumazenil on midazolam-induced depression of the ventilatory response to hypoxia during isohypercarbia

BACKGROUND

While flumazenil reverses benzodiazepine-induced sedation, its ability to antagonize the ventilatory depressant effects of benzodiazepines has not been fully established. A randomized, double-blind study was conducted to determine whether flumazenil effectively reverses midazolam-induced depression of the hypoxic ventilatory response.

METHODS

Twelve healthy male volunteers received intravenous midazolam 0.12 +/- 0.01 mg.kg-1 followed by either flumazenil 1.0 mg or placebo. Hypoxic ventilatory response was measured using an isocapnic rebreathing technique: as Spo2 decreased to 70% VE and tidal volume were continuously recorded. Hypoxic response determinations were performed before and after midazolam, as well as 3, 30, 60, 120, and 180 min after flumazenil or placebo.

RESULTS

After midazolam, the slope of the hypoxic ventilatory response curve (VE vs. SpO2) decreased to 0.59 +/- 0.05 (means +/- SE) times its premidazolam baseline; likewise, at Spo2 = 90%, minute ventilation (VE90) and tidal volume (TV90) decreased to 0.70 +/- 0.04 and 0.62 +/- 0.03 times baseline, respectively. Three minutes after flumazenil, the slope increased to 1.10 +/- 0.13 times baseline (P < 0.05 vs. postmidazolam), while following placebo, it was only 0.81 +/- 0.09 times baseline (P = NS vs. postmidazolam, P < 0.05 between treatments). VE90 and TV90, after flumazenil, increased to 1.45 +/- 0.15 and 1.27 +/- 0.09 times baseline, respectively (P < 0.05 vs. postmidazolam); these increases were significantly greater than the corresponding changes observed after placebo (P < 0.05 between treatments).

CONCLUSIONS

It was concluded that, after sedation with midazolam, flumazenil causes a greater increase in hypoxic ventilatory response during isohypercarbic conditions than does placebo, and may, therefore, be useful in the treatment of midazolam-induced ventilatory depression.

Salbutamol disposition and dynamics in conscious rabbits: influence of the route of administration and of the dose

This study assessed the influence of dose and route of administration on salbutamol kinetics and hypokaliemic effect. Salbutamol plasma kinetics were studied in a first group of 6 rabbits who received 60, 800, and 60 micrograms/kg by the intravenous (iv), oral (po), and intratracheal (it) routes, respectively, at 1-week intervals. A second group of 6 rabbits received 120, 2400, and 120 micrograms/kg of salbutamol by the same three routes. Multiple blood samples were withdrawn to assay salbutamol and potassium. Following iv salbutamol (60 micrograms/kg), total plasma clearance was 82 +/- 5 ml/min per kg, apparent volume of distribution was 5.0 +/- 0.5 l/kg, and terminal half-life was 41 +/- 2 min. Similar values were estimated when 120 micrograms/kg of salbutamol was administered iv or was given po or it. The bioavailability of po and it salbutamol was approximately 1 and 20%, respectively. For the first group, the maximal decrease in plasma potassium elicited by salbutamol was 0.80 +/- 0.19, 0.48 +/- 0.22, and 0.78 +/- 0.46 mmol/l, and for the second group, maximal decrement was 1.31 +/- 0.37, 0.70 +/- 0.24, and 0.84 +/- 0.17 mmol/l for the iv, po, and it routes, respectively. Compared to salbutamol peak plasma concentrations, maximal decrease in plasma potassium appeared between 60 and 108 min later for the iv route, 90 and 25 min later for po and it routes, and for this reason, the hypokaliemic effect was not associated to salbutamol plasma concentrations. The hypokaliemic effect was dependent upon the route, e.g., po > it > iv.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of salbutamol on gastroesophageal reflux in healthy volunteers and patients with asthma

The aim of this work was to establish whether beta-adrenergic agonists promote or increase gastroesophageal reflux in patients with asthma. Ten healthy individuals and eight patients with asthma were studied on 2 different days. One day they received a placebo, and the other day they received 4 mg of salbutamol by mouth. Complete measurements of esophageal manometry were performed before and every 30 minutes for 210 minutes after the administration of the drugs. Esophageal pH was measured continuously for the duration of the experiment. The results demonstrate that (1) salbutamol had no effect on the lower esophageal sphincter pressure gradient, the peak esophageal contraction pressure, or the number and duration of reflux episodes in patients with asthma and normal individuals, and (2) patients with asthma have a resting lower esophageal sphincter pressure higher than healthy subjects. We conclude that the administration of salbutamol does not affect esophageal function.