Genetic variants of coagulation factor XIII, postmenopausal estrogen therapy, and risk of nonfatal myocardial infarction

We hypothesized that possession of either of 2 functional coagulation factor XIII polymorphisms, one within subunit A (Val34Leu) and one within subunit B (His95Arg), might modulate the prothrombotic effects of estrogen and help to explain the variation in incidence of arterial thrombotic events among postmenopausal women using hormone replacement therapy. In a population-based case-control study of 955 postmenopausal women, we assessed the associations of factor XIII genotypes and their interactions with estrogen therapy on risk of nonfatal myocardial infarction (MI). The presence of the factor XIIIA Leu34 allele was associated with a reduced risk of MI (odds ratio [OR] = 0.70, 95% confidence interval [95% CI] = 0.51-0.95). The presence of the factor XIIIB Arg95 allele had little association with MI risk. Neither factor XIII polymorphism alone significantly modified the association between the risk of MI and current estrogen use. In exploratory analyses, however, there was a significant factor XIII subunit gene-gene interaction. Compared to women homozygous for both common factor XIII alleles, the Arg95 variant was associated with a reduced risk of MI in the presence of the Leu34 variant (OR = 0.36, 95% CI = 0.17-0.75) but not in the absence of the Leu34 variant (OR = 1.11, 95% CI = 0.69-1.79). Moreover, among women who had at least 2 copies of the variant factor XIII alleles and were current estrogen users, the risk of MI was reduced by 70% relative to estrogen nonusers with fewer than 2 factor XIII variant alleles (P value for interaction =.03). If confirmed, these findings may permit a better assessment of the cardiovascular risks and benefits associated with postmenopausal estrogen therapy.

Resuscitation of residents with do not resuscitate orders in long-term care facilities

BACKGROUND

A considerable number of emergency medical services (EMS) responses for cardiac arrest occur in long-term care facilities. In some instances, these responses are for residents who have expressed wishes not to be resuscitated by signing a do not resuscitate (DNR) order.

OBJECTIVES

To assess the magnitude of EMS use for cardiac arrest in long-term care facilities for residents with DNR orders and to determine reasons why EMS is called.

METHODS

A retrospective study was conducted using data collected from medical incident reports between July 1999 and December 2000 for all persons experiencing cardiac arrest in long-term care facilities defined as nursing homes, adult family homes, and assisted-living centers in King County, Washington, excluding Seattle. The authors also surveyed facilities to determine their policies for calling 9-1-1 in the event of cardiac arrest. Results. Of the 392 cardiac arrests in long-term care facilities to which EMS responded, 139 (35%) of the residents had DNR orders. Of these 139, 29 (21%) received attempted resuscitation by EMS. The problem appeared to be greater among nursing homes and adult family homes than in assisted-living centers. Among nursing homes, the primary reason for an EMS call was concern for validity of the DNR order, whereas among adult family homes, the primary concern was appropriate medical authority to declare death.

CONCLUSION

Efforts to clarify existing regulations, streamline the DNR transfer process, and improve communication between EMS and long-term care facilities may result in better fulfillment of residents' end-of-life wishes and a saving of EMS resources.

Temporal trends in sudden cardiac arrest: a 25-year emergency medical services perspective

BACKGROUND

Little is known about temporal trends in survival and prognostic characteristics of patients with out-of-hospital cardiac arrest treated by emergency medical services (EMS). We hypothesized that an evolving combination of beneficial and adverse factors may contribute to temporal patterns of survival.

METHODS AND RESULTS

We evaluated a population-based cohort of EMS-treated adult patients with cardiac arrest (n=12 591) from 1977 to 2001 in King County, Washington. Time was grouped into an initial 5-year period and 5 successive 4-year periods. We sought to determine the potential impact of temporal changes in prognostic factors typically beyond EMS control termed "fate" factors (for example, patient age) and factors implemented by EMS termed "program" factors (programs of dispatcher-assisted cardiopulmonary resuscitation and basic life support defibrillation). Several characteristics associated with survival changed over time. Observed survival did not change over time among all patients with cardiac arrest (OR=0.98 [0.95, 1.01], trend for each successive time period) and improved over time among patients with witnessed ventricular fibrillation (OR=1.05 [1.01, 1.09]). In models that included all patients with cardiac arrest and controlled for fate factors, advancing time period was associated with an increase in survival (OR=1.08 [1.05, 1.11]). Conversely, in models that controlled for program factors, advancing time period was associated with a decrease in survival (OR=0.95 [0.93, 0.98]). Results were similar among patients with witnessed ventricular fibrillation.

CONCLUSIONS

The static temporal pattern of survival from cardiac arrest appeared to result from an evolving balance of prognostic factors. Programs implemented by EMS appeared to counter adverse temporal trends in prognostic factors typically beyond EMS control.

Hormone replacement therapy and the risk of incident congestive heart failure: the Cardiovascular Health Study

BACKGROUND

The development of congestive heart failure (CHF) in older persons is related to a variety of mechanisms. Hormone replacement therapy (HRT) affects several of the pathways that may be important in the development of CHF. We hypothesized that HRT would be associated with a decreased risk of incident CHF.

METHODS

Using Cox proportional-hazards regression, we assessed the risk of incident CHF (n = 304) associated with time-dependent past and current use of HRT compared to never use. The Cardiovascular Health Study is a prospective cohort study of community-dwelling adults aged 65 years and older. This analysis included female participants without a history of CHF at baseline (n = 3223).

RESULTS

At baseline, 62% were never users, 26% were past users, and 12% were current users of HRT. Compared with never users, the multivariable relative risk (RR) of CHF was 1.01 (95% confidence interval [95% CI] 0.76,1.34) for past users and 1.34 (0.93,1.94) for current users. Results were similar among most treatment and clinical subgroups, except that the association of current HRT with CHF appeared to depend on body mass index (BMI) or osteoporosis status. The RR was 0.82 (0.43,1.60) for normal weight women, 1.65 (0.95,2.88) for overweight women, and 2.22 (1.06,4.67) for obese women (p = 0.01 for interaction). Similarly, the RR was 0.15 (0.04,0.65) for women with osteoporosis and 1.82 (1.25,2.65) for women without osteoporosis (p = 0.001 for interaction).

CONCLUSIONS

Overall, HRT was not associated with the risk of incident CHF, although BMI and osteoporosis appeared to modify the association of HRT with CHF. The risk of CHF was lower in patients with lower BMI or osteoporosis.

Emergency medical services and mortality from heart disease: a community study

STUDY OBJECTIVES

Little is known regarding the potential effects of emergency medical services (EMS) on total heart disease mortality. Although EMS may provide health benefits in less acute cardiac conditions, its immediate, measurable, and direct effect on heart disease mortality is through resuscitation of persons suffering out-of-hospital cardiac arrest. The purpose of this study was to examine the involvement and potential mortality benefit of out-of-hospital EMS care of cardiac arrest on community heart disease mortality.

METHODS

The investigation was an observational study of all persons with death events resulting from heart disease as defined by heart disease deaths and deaths averted (persons successfully resuscitated from out-of-hospital cardiac arrest by EMS) in a single county from January 1, 2000, through December 31, 2000. The county of study has a population of nearly 2 million people and is composed of urban, suburban, and rural components. State vital records and EMS reports were used to ascertain deaths resulting from heart disease and deaths averted.

RESULTS

In the year 2000, 3,577 persons died as a result of heart disease, and 128 persons were successfully resuscitated and discharged from the hospital, for a total of 3,705 death events. EMS responded to 39% (1,428/3,705) of all heart disease death events and 57% (1,428/2,516) of out-of-hospital events, resulting in a 3.5% (128/3,705) reduction in overall heart disease mortality and a 5.1% (128/2,516) reduction in out-of-hospital mortality.

CONCLUSION

EMS was involved in the majority of out-of-hospital heart disease death events, resulting in a measurable reduction in heart disease mortality.

Time to first shock by emergency medical technicians with automated external defibrillators

The interval from collapse to electrical rescue shock is a critical determinant of successful defibrillation in cardiac arrest. In order to achieve the earliest possible defibrillation, many emergency medical services (EMS) systems equip first-responding units with an automated external defibrillator (AED).

OBJECTIVE

To measure the time from on-scene emergency medical technician (EMT) recognition of cardiac arrest to AED application and shock in ventricular fibrillation (VF) arrest. In addition, the authors sought to understand the reasons for delays.

METHODS

Using the AED recordings and written EMS reports, the authors conducted a retrospective cohort study of all persons who experienced an EMS-attended VF cardiac arrest in which an AED was applied and a shock delivered by an EMT, from January 1999 through December 2000 (n = 177). Based on the bimodal distribution of times, two groups were assembled: no delay (time to shock < or = 90 seconds) and delayed (time to shock > 90 seconds). Patient and event characteristics associated with delay status were determined using Mantel-Haenszel methods.

RESULTS

The median (25th, 75th percentile) time from cardiac arrest recognition to shock was 51 (43, 64) seconds. Ninety-four percent (n = 166) of the cohort received a shock within 90 seconds. Delayed shock was associated with unwitnessed arrest status (odds ratio = 9.3, 95% confidence interval = 2.3, 36.8) and nursing home location (odds ratio = 10.0, 95% confidence interval = 2.1, 47.5).

CONCLUSION

The findings suggest that a 1-minute goal and a 90-second minimum standard for time to first shock are appropriate for EMT AED defibrillation in the field.

Smoking status and risk for recurrent coronary events after myocardial infarction

BACKGROUND

Questions remain about the importance of smoking and smoking cessation after incident myocardial infarction.

OBJECTIVE

To assess the association between smoking status and risk for recurrent coronary events.

DESIGN

Retrospective, population-based, inception cohort study.

SETTING

Health maintenance organization from 1986 to 1996.

PATIENTS

2619 persons who survived to hospital discharge after a first myocardial infarction.

MEASUREMENTS

Relative risk (RR), assessed by using Cox proportional hazards regression analysis, for recurrent coronary events in nonsmokers (persons with no history of smoking), former smokers (persons who had stopped smoking before infarction), quitters (persons who stopped smoking after infarction), and active smokers (persons who continued smoking after infarction).

RESULTS

At the time of incident infarction, 33.6% of patients were nonsmokers, 35.5% were former smokers, and 30.9% were active smokers. Of the 808 persons who were active smokers at the time of incident infarction, 449 quit smoking during hospitalization or after discharge. With nonsmokers as the reference group, the multivariable RR for recurrent coronary events (n = 433) was 1.17 (95% CI, 0.93 to 1.43) for former smokers and 1.51 (CI, 1.10 to 2.07) for active smokers. Among quitters, the RR decreased as duration of cessation increased: With nonsmokers as the reference group, the RR for quitters was 1.62 (CI, 1.02 to 2.61) if the duration of cessation was 0 to less than 6 months, 1.60 (CI, 0.97 to 2.60) if the duration was 6 to less than 18 months, 1.48 (CI, 0.76 to 2.51) if the duration was 18 to less than 36 months, and 1.02 (CI, 0.54 to 1.86) if the duration was 36 months or more (P = 0.01 for trend).

CONCLUSION

After incident myocardial infarction, smoking was associated with an elevated risk for recurrent coronary events. In persons who quit smoking after infarction, the risk declined to equal that of nonsmokers by 3 years after cessation.

An emergency medical services program of alternate destination of patient care

OBJECTIVE

The emergency department (ED) is ideally reserved for urgent health needs. The ED, however, is often the site of care for nonurgent conditions. The authors investigated whether emergency medical technicians could decrease ED use by patients with nonurgent concerns who use 911 by appropriately identifying and triaging them to alternate care destinations.

METHODS

From August 2000 through January 2001, two King County fire-based emergency medical services (EMS) agencies participated in an alternate care destination program for patients with specific low-acuity diagnosis codes (intervention group). Eligible patients were offered care at a clinic-based destination as an alternate to the ED (n = 1,016). The frequency of the destination of care (ED, clinic, or home) for the intervention group was compared with a matched control group that was comprised of a preintervention historical cohort of EMS encounters from the same two fire-based agencies and with the same acuity and diagnosis criteria and seasonal interval (n = 2,617).

RESULTS

Compared with the preintervention group, a smaller proportion of patients in the intervention group received care in the ED (44.6% vs. 51.8%, p = 0.001), while a greater proportion of patients in the intervention group received clinic care (8.0% vs. 4.5%, p = 0.001) or home care (no transport) (47.4 vs. 43.7%, p = 0.043). Results were comparable when adjusted for other patient characteristics. Similar relationships were not evident among nonparticipating King County EMS agencies. Based on physician review and patient interview, the alternate care intervention appeared to be safe and satisfactory.

CONCLUSION

An EMS-based program may represent one approach to limiting nonurgent ED use.

A systematic study of Epstein-Barr virus serologic assays following acute infection

We determined the presence of IgG and IgM antibody to viral capsid antigen (VCA-IgG, VCA-IgM) and IgG antibody to the Epstein-Barr virus nuclear antigen (EBNA) by indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA) during the acute illness and at 1, 2, 6, and 48 months in a prospective population-based case series of 95 persons with an acute illness serologically confirmed as Epstein-Barr virus infection. The acute illness was characterized by the presence of VCA-IgG and VCA-IgM (by ELISA) and by the absence of EBNA in most, but not all, patients. During follow-up, VCA-IgG antibodies remained detectable in all patients, while the proportion with VCA-IgM declined and the number with detectable EBNA antibodies steadily increased. The primary differences between the 2 serologic test methods were the increased persistence of VCA-IgM during follow-up by ELISA and the earlier detection of EBNA by IFA. Clinicians should consider the illness stage and the laboratory technique to appropriately interpret serologic test results in suspected cases of mononucleosis caused by the Epstein-Barr virus.

Intentions to use an automated external defibrillator during a cardiac emergency among a group of seniors trained in its operation

OBJECTIVE

By decreasing the time to defibrillation, automated external defibrillators (AEDs) provide an opportunity for lay people to improve survival in out-of-hospital sudden cardiac arrest. We examined how beliefs, expectations, and actual performance are related to intentions to use an AED during a future heart emergency among a group of seniors.

DESIGN AND OUTCOME MEASURES

One hundred fifty-nine seniors who had been previously trained in the operation of an AED were tested on their AED skills and asked about their perceptions regarding their AED skills; their expectations that an AED would save the life of a cardiac arrest victim; and their intentions to use an AED during a future cardiac event.

RESULTS

Logistic regression analyses showed that greater self-perceived ability to use an AED better actual performance on skills assessment but not expectations regarding the efficacy of AED treatment were independently associated with positive intentions to use an AED in a future heart emergency.

CONCLUSIONS

The likelihood that an elderly lay bystander will actually use an AED during a cardiac event may be closely tied to perceptions of his or her ability to operate an AED.

Dispatcher-assisted cardiopulmonary resuscitation and survival in cardiac arrest

BACKGROUND

Early cardiopulmonary resuscitation (CPR) improves survival in out-of-hospital cardiac arrest, and dispatcher-delivered instruction in CPR can increase the proportion of arrest victims who receive bystander CPR before emergency medical service (EMS) arrival. However, little is known about the survival effectiveness of dispatcher-delivered telephone CPR instruction.

METHODS AND RESULTS

We evaluated a population-based cohort of EMS-attended adult cardiac arrests (n=7265) from 1983 through 2000 in King County, Washington, to assess the association between survival to hospital discharge and 3 distinct CPR groups: no bystander CPR before EMS arrival (no bystander CPR), bystander CPR before EMS arrival requiring dispatcher instruction (dispatcher-assisted bystander CPR), and bystander CPR before EMS arrival not requiring dispatcher instruction (bystander CPR without dispatcher assistance). In this cohort, 44.1% received no bystander CPR before EMS arrival, 25.7% received dispatcher-assisted bystander CPR, and 30.2% received bystander CPR without dispatcher assistance. Overall survival was 15.3%. Using no bystander CPR as the reference group, the multivariate adjusted odds ratio of survival was 1.45 (95% confidence interval [CI], 1.21, 1.73) for dispatcher-assisted bystander CPR and 1.69 (95% CI, 1.42, 2.01) for bystander CPR without dispatcher assistance.

CONCLUSION

Dispatcher-assisted bystander CPR seems to increase survival in cardiac arrest.

Dispatcher assistance and automated external defibrillator performance among elders

OBJECTIVES

Automated external defibrillators (AEDs) provide an opportunity to improve survival in out-of-hospital, ventricular fibrillation (VF) cardiac arrest by enabling laypersons not trained in rhythm recognition to deliver lifesaving therapy. The potential role of emergency dispatchers in the layperson use of AEDs is uncertain. This study was performed to examine whether dispatcher telephone assistance affected AED skill performance during a simulated VF cardiac arrest among a cohort of older adults. The hypothesis was that dispatcher assistance would increase the proportion who were able to correctly deliver a shock, but might require additional time.

METHODS

One hundred fifty community-dwelling persons aged 58-84 years were recruited from eight senior centers in King County, Washington. All participants had received AED training approximately six months previously. For this study, the participants were randomized to AED operation with or without dispatcher assistance during a simulated VF cardiac arrest. The proportions who successfully delivered a shock and the time intervals from collapse to shock were compared between the two groups.

RESULTS

The participants who received dispatcher assistance were more likely to correctly deliver a shock with the AED during the simulated VF cardiac arrest (91% vs 68%, p = 0.001). Among those who were able to deliver a shock, the participants who received dispatcher assistance required a longer time interval from collapse to shock [median (25th, 75th percentile) = 193 seconds (165, 225) for dispatcher assistance, and 148 seconds (138, 166) for no dispatcher assistance, p = 0.001].

CONCLUSIONS

Among older laypersons previously trained in AED operation, dispatcher assistance may increase the proportion who can successfully deliver a shock during a VF cardiac arrest.

Body mass index and the risk of recurrent coronary events following acute myocardial infarction

Although excess adiposity appears to increase the risk of coronary heart disease in the general population, its importance in patients with established coronary disease is less defined. We evaluated a population-based inception cohort of survivors to hospital discharge following first acute myocardial infarction (AMI) (n = 2,541) to assess the association between body mass index (BMI) and the risk of recurrent coronary events and to explore the mechanisms for this relation. Using Cox proportional-hazards regression, we assessed the risk of recurrent coronary events associated with levels of adiposity as defined by BMI and then investigated potential mechanisms through which adiposity conferred risk by examining how adjustment for diabetes mellitus, systemic hypertension, and dyslipidemia affected the association. Forty-one percent of the cohort were overweight (BMI 25 to 29.9), and 27.8% were obese (BMI > or =30). After adjustment for other risk factors, the risk of recurrent coronary events (n = 418) increased as BMI increased, especially among those who were obese. Using a BMI of 16 to 24.9 as the reference group, for mildly overweight patients (BMI 25 to 27.4), the relative risk (RR) was 0.93 (95% confidence interval [CI] 0.70 to 1.24); it was 1.16 for more severe overweight patients (BMI 27.5 to 29.9; 95% CI 0.87 to 1.55). For patients with class I obesity (BMI 30 to 34.9), the RR was 1.49 (95% CI 1.12 to 1.98), and for class II to III obesity (BMI > or =35), the RR was 1.80 (95% CI 1.30 to 2.48). We estimated that clinical measurements of diabetes, hypertension, and dyslipidemia explained approximately 43% of this risk. Thus, excess adiposity as measured by BMI was associated with an increased risk of recurrent coronary events following AMI, particularly among those who were obese.

Prospective study of the natural history of infectious mononucleosis caused by Epstein-Barr virus

BACKGROUND

Knowledge regarding the clinical characteristics and natural history of acute infectious mononucleosis is based largely on older, often retrospective, studies without systematic follow-up. Differences in diagnosis, methodology, or treatment between historical and current practice might affect an understanding of this illness.

METHODS

Using a prospective case series design, we enrolled 150 persons with an acute illness serologically confirmed as Epstein-Barr virus infection. The goal of the study was to assess symptoms, physical examination findings, laboratory tests, and functional status measures during the acute presentation and 1, 2, and 6 months later.

RESULTS

Acutely, infectious mononucleosis was characterized by the symptoms of sore throat and fatigue and substantial functional impairment. Objective physical and laboratory examination findings included pharyngitis and cervical lymphadenopathy, a moderate absolute and atypical lymphocytosis, and mildly elevated transaminase levels. The traditional signs of fever and splenomegaly were relatively uncommon. By 1 month, most symptoms and signs and all laboratory tests had returned to normal. Fatigue, cervical lymphadenopathy, pharyngitis, and functional health status improved more slowly.

CONCLUSIONS

In contemporary practice most of the classical illness features of infectious mononucleosis are observed. Symptoms, signs, and poor functioning might be protracted in some patients.

Acute infectious mononucleosis: characteristics of patients who report failure to recover

PURPOSE

We sought to determine how often acute mononucleosis precipitates chronic illness, and to describe the demographic, clinical, and psychosocial features that characterize patients who report failure to recover.

SUBJECTS AND METHODS

We enrolled 150 patients with infectious mononucleosis during the acute illness and asked them to assess their recovery at 2 and 6 months. At baseline, we performed physical and laboratory examinations; obtained measures of psychological and somatic functioning, social support, and life events; and administered a structured psychiatric interview.

RESULTS

Self-assessed failure to recover was reported by 38% of patients (55 of 144) at 2 months and by 12% (17 of 142) at 6 months. Those who had not recovered reported a persistent illness characterized by fatigue and poor functional status. No objective measures of disease, including physical examination findings or serologic or laboratory markers, distinguished patients who failed to recover from those who reported recovery. Baseline predictors for failure to recover at 2 months were older age (odds ratio [OR] = 1.4, 95% confidence interval [CI]: 1.1 to 1.8, per 5-year increase), higher temperature (OR = 1.5, 95% CI: 1.1 to 2.2, per 0.5 degrees C increase), and greater role limitation due to physical functioning (OR = 1.5, 95% CI: 1.2 to 1.9, per 20-point decrease in Short Form-36 score). At 6 months, baseline predictors for failure to recover included female sex (OR = 3.3, 95% CI: 1.0 to 12), a greater number of life events more than 6 months before the disease began (OR = 1.7, 95% CI: 1.1 to 2.5, per each additional life event), and greater family support (OR = 1.9, 95% CI: 1.1 to 4.2, per 7-point increase in social support score).

CONCLUSIONS

We were not able to identify objective measures that characterized self-reported failure to recover from acute infectious mononucleosis. The baseline factors associated with self-reported failure to recover at 2 months differed from those associated with failure to recover at 6 months. Future studies should assess the generalizability of these findings and determine whether interventions can hasten recovery.