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Biomedical subjects

J S Martin

Publications and source records attributed to J S Martin.

At least 37 records · Page 2Linked to original sources
PubMed1997

Absence of association between insurance copayments and delays in seeking emergency care among patients with myocardial infarction.

BACKGROUND: The requirement of copayments for emergency care is thought to control costs by reducing "inappropriate" visits to the emergency department. However, requiring copayments may lead to adverse outcomes if patients delay seeking care for emergency conditions. To determine whether such requirements are associated with delays in seeking care, we examined the length of time from the onset of symptoms to arrival at the hospital among patients with myocardial infarction who did or did not have required insurance copayments. METHODS: All patients were enrolled in a single health maintenance organization (HMO) and presented with myocardial infarction at 1 of 19 hospitals in King County, Washington, from 1989 through 1994. There were 602 patients whose health insurance required a copayment for emergency department care (range, $25 to $100) and 729 patients with no copayment requirement. Data on the time to presentation were obtained from a review of ambulance and hospital records. RESULTS: The median length of time from the onset of symptoms to arrival at the hospital, as adjusted for age, sex, and race, was 135 minutes for the copayment group and 137 minutes for the group with no copayment (95 percent confidence interval for the difference, -19 to +16 minutes). There was no significant association between the presence or absence of a copayment requirement and the time to arrival at the hospital after adjustment for calendar year, income, educational level, cardiac history, or clinical symptoms. Since some patients may be unaware of their copayment requirement, we performed a subgroup analysis of data on patients who had a previous visit to the emergency department with the same copayment status - that is, of patients who were likely to know about their copayment. This analysis also showed no significant association between the requirement for a copayment and delays in seeking treatment. CONCLUSIONS: For privately insured patients in this HMO, the requirement of modest, fixed copayments for emergency services did not lead to delays in seeking treatment for myocardial infarction.

Adult↗
PubMed1997

Acute experimental distal colitis alters colonic transit in rats.

Data from humans with active distal colitis suggest that the proximal colon exhibits increased contractile activity and delayed transit, whereas the distal colon shows decreased contractile activity and rapid transit. The present study used the acetic acid rat model of experimental colitis to determine the effect of distal colitis on total and regional colonic transit in vivo and on the in vitro contractility of circular smooth muscle from the proximal and distal colon. Distal colitis was induced in rats by intracolonic administration of 4% acetic acid; sham control rats received saline enemas. Control and colitic rats were studied 2 days postenemas. Total colon transit was determined by calculating the geometric center of distribution of a radiolabeled marker (51Cr) instilled into the proximal colon. Regional transit was assessed by expressing the radioactivity in the cecum, proximal and distal colon, and excreted stool as a percent of total radioactivity. Muscle strips from the proximal and distal colon were stimulated with 100 microM acetylcholine (ACh) and 60 mM KCl and the tension was expressed as kilograms per square centimeter. Distal colitis was characterized by decreased total colon transit, increased retention of marker in the cecum and proximal colon, and decreased retention of marker in the distal colon. In vitro contractility studies revealed that distal colitis increased proximal colon circular smooth muscle contractility and decreased distal colon circular smooth muscle contractility to both ACh and potassium. Distal colitis is associated with regional differences in colonic circular smooth muscle contractility, which may contribute to delayed transit in the proximal colon and rapid transit in the distal colon.

Acetylcholine↗
PubMed1997

Use and accuracy of state death certificates for classification of sudden cardiac deaths in high-risk populations.

In a large cohort of patients with known or suspected coronary disease, we evaluated the characteristics of 407 patients who died after hospital discharge and tested whether the state death certificate can be used to classify deaths as sudden cardiac versus nonsudden. Compared with a paramedic classification system based on heart rhythm, the death certificate-based classification resulted in a sensitivity that ranged from 78% to 85% and a specificity that ranged from 25% to 58%. We conclude that the death certificate can be used to identify cases of sudden cardiac death in patients at high risk; however, there is a substantial rate of false-positive sudden death classification.

Aged↗
PubMed1997

Long-term implications of racial differences in the use of revascularization procedures (the Myocardial Infarction Triage and Intervention registry).

The purpose of this study was to determine if less intensive use of revascularization procedures in black patients influenced the long-term survival of patients hospitalized for acute myocardial infarction (AMI) in metropolitan Seattle. From January 1988 through June 1994, AMI developed in 420 (4%) black and 10,834 white patients before hospital discharge or death. Black patients were 6 years younger, more socioeconomically disadvantaged, and had more hypertension, diabetes, and less prior coronary surgery. Similar proportions of black and white patients received thrombolytic therapy or cardiac catheterization. However, during hospitalization, 18% of black patients underwent coronary angioplasty compared with 26% of white patients (p = 0.0004); coronary artery bypass surgery was also used less frequently in black patients (7% vs 12%, p = 0.002). Unadjusted 2-year survival was 79% for black patients and 77% for white patients (p = 0.12). After adjusting for age, clinical variables, and the use of cardiac catheterization, thrombolytic therapy, and revascularization, race was not associated with long-term survival (hazard ratio = 0.92, 95% confidence interval = 0.73 to 1.17). Despite the less intensive use of revascularization procedures in black patients in Seattle, long-term survival after AMI was similar in the two groups of patients.

Age Factors↗
PubMed1997

Randomized controlled trial of superovulation and insemination for infertility associated with minimal or mild endometriosis.

OBJECTIVE: To evaluate the efficacy of superovulation and IUI versus no treatment for infertility associated with minimal or mild endometriosis. DESIGN: Randomized trial. SETTING(S): London Health Sciences Centre, University Campus, The University of Western Ontario, London, Ontario; and Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada. PATIENT(S): Three hundred eleven cycles in 103 couples in whom minimal or mild endometriosis was the sole identified subfertility factor. INTERVENTION(S): Superovulation with FSH and IUI. MAIN OUTCOME MEASURE(S): Live birth. RESULT(S): Live birth followed 14 of 127 (11%) superovulation and IUI cycles and 4 of 184 (2%) no-treatment cycles. The odds ratio was 5.6 (95% confidence interval 1.8 to 17.4) in favor of superovulation and IUI. CONCLUSION(S): Treatment with superovulation and IUI was associated with superior outcome both by crude live-birth rates and proportional hazard analysis.

Adult↗
PubMed1997

Electric field stimulation-induced guinea pig gallbladder contractions: role of calcium channels in acetylcholine release.

Gallbladder motility is modulated by intrinsic cholinergic neurons. The aims of this study were to determine: (1) the effect of electric field stimulation (EFS) on guinea pig gallbladder smooth muscle, and (2) the role of calcium channels in mediating neurotransmitter release. Gallbladder muscle strips were studied isometrically in vitro. EFS (1-16 Hz, 100 V, 0.5-msec pulse width, 30-sec train duration) was used to activate the intrinsic nerves. Exogenous acetylcholine was also used to directly stimulate the smooth muscle. EFS produced a frequency-dependent contractile response that was completely abolished by tetrodotoxin. EFS-induced contractions at 16 Hz were suppressed by 84 +/- 4% with atropine, whereas hexamethonium had no effect. The L-type calcium channel blocker, nifedipine, reduced EFS contractions by 51 +/- 4%, whereas it reduced contractions to acetylcholine by only 11 +/- 5%. The N-type calcium channel blocker, omega-conotoxin GVIA, reduced EFS-induced contractions by 22 +/- 9%, but did not affect acetylcholine-induced contractions. EFS-induced contractions of the guinea pig gallbladder are primarily mediated by activation of postganglionic cholinergic neurons. The acetylcholine release from these cholinergic neurons is regulated by L- and N-type calcium channels. The inhibitory effect of calcium channel blockers on the gallbladder seen in vivo may be in part related to inhibition of acetylcholine release from the intrinsic cholinergic nerves of the gallbladder.

Acetylcholine↗
PubMed1997

Aggressive papillary tumor of the temporal bone: delayed extensive recurrence following radiation therapy.

Endolymphatic sac tumors have been characterized as aggressive papillary tumors of the temporal lobe, exhibiting extensive bony destruction and intracranial extension. This report describes the delayed recurrence of an aggressive endolymphatic sac tumor following full course radiotherapy many years previously. The discussion reviews the current literature on these aggressive lesions with emphasis on clinical presentation, diagnosis, radiographic and histologic appearance and management. This case highlights the need for total surgical excision in the management of these lesions. Radiotherapy as primary management may slow tumor growth but does not appear to be an appropriate therapeutic modality for cure.

Case Reports↗
PubMed1997

Assessment of the AO/ASIF fracture classification for the distal tibia.

OBJECTIVES: The purpose of this study was to assess the interobserver reliability and intraobserver reproducibility of the AO/ASIF and Rüedi and Allgöwer classifications for fractures of the distal tibia, and to determine the benefit of a computed tomography (CT) scan and experience on observer agreement for several fracture characteristics, including classification. METHODS: The radiographs of forty-three fractures of the distal tibia, fourteen of which had CT scans, were assessed by groups of experienced and less-experienced observers. Each case was classified according to the AO/ASIF and Rüedi and Allgöwer systems. Several other fracture characteristics also were assessed. The kappa coefficient of agreement was calculated and used to compare the interobserver reliability and intraobserver reproducibility of the classification systems and to determine the benefit of experience and CT scans. The intraclass correlation coefficient was used to assess noncategoric data. RESULTS: Interobserver and intraobserver agreements were good when classifying fractures into AO/ASIF types and significantly better than that for the Rüedi and Allgöwer system. However, agreement was poor when classifying the fractures into AO/ASIF groups. For most assessments, the experienced group tended to have higher levels of interobserver agreement, but not intraobserver agreement. Viewing the CT scans improved agreement on the percentage of articular surface involved, but it did not improve interobserver reliability or intraobserver reproducibility for either of the classification systems. CONCLUSION: The AO/ASIF classification for fractures of the distal tibia has good observer agreement at the type level, but poor agreement at the group level. Experience tends to improve interobserver agreement, but not intraobserver agreement. Viewing CT scans does not improve agreement on classification, but it tends to improve agreement on articular surface involvement.

Ankle Injuries↗
PubMed1997

Acute experimental colitis decreases colonic circular smooth muscle contractility in rats.

Distal colitis decreases the contractility of the underlying circular smooth muscle. We examined how time after injury and lesion severity contribute to the decreased contractility and how colitis alters the calcium-handling properties of the affected muscle. Distal colitis was induced in rats by intrarectal administration of 4% acetic acid. Contractile responses to acetylcholine, increased extracellular potassium, and the G protein activator NaF were determined for circular muscle strips from sham control and colitic rats at days 1, 2, 3, 7, and 14 postenemas. Acetylcholine stimulation of tissues from day 3 colitic rats was performed in a zero calcium buffer, in the presence of nifedipine, and after depletion of intracellular stores of calcium. The colitis was graded macroscopically as mild, moderate, or severe. Regardless of agonist, maximal decrease in force developed 2 to 3 days posttreatment, followed by a gradual return to control by day 14. The inhibitory effect of colitis on contractility increased with increasing severity of inflammation. Limiting extracellular calcium influx had a greater inhibitory effect on tissues from colitic rats; intracellular calcium depletion had a greater inhibitory effect on tissues from control animals. The data suggest that both lesion severity and time after injury affect the contractile response of circular smooth muscle from the inflamed distal colon. Impaired utilization of intracellular calcium may contribute to the decreased contractility.

Acetic Acid↗
PubMed1997

Current classification of fractures. Rationale and utility.

Fracture classification systems are used on a daily basis in any busy orthopedic clinic. They are an essential means by which physicians communicate, make treatment decisions, estimate prognosis, and report and compare results. Until recently, these classifications have been designed, accepted, and utilized without formal critique. By studying and understanding the shortcomings of previous systems, we can use this knowledge to construct better ones. Ideally, a fracture classification, like any classification, should be reliable, reproducible, all inclusive, mutually exclusive, logical, and clinically useful. The AO/ASIF classification of long bone fractures provides a unified scheme of classification for fractures of the entire skeleton. Despite addressing many of the faults of previous classifications, the observer agreement for this system drops to unacceptable levels at the group and subgroup levels. Further study is warranted to determine how this agreement can be improved.

Communication↗
PubMed1996

A comparison of thrombolytic therapy with primary coronary angioplasty for acute myocardial infarction. Myocardial Infarction Triage and Intervention Investigators.

BACKGROUND: Several relatively small randomized trials have shown that primary angioplasty results in a better short-term outcome than thrombolytic therapy in patients with acute myocardial infarction. These results, however, have not been duplicated other than in investigational trials. METHODS: We compared mortality during hospitalization and long-term mortality, as well as the use of resources, among 1050 patients in a primary-angioplasty group and 2095 patients in a thrombolytic-therapy group. Patients were selected from the Myocardial Infarction Triage and Intervention Project Registry cohort of 12,331 consecutive patients admitted with acute myocardial infarction to 19 Seattle hospitals between 1988 and 1994. Because of the potential for selection bias, several subgroup analyses were performed that included patients eligible for thrombolysis, high-risk patients, and patients in the primary-angioplasty group who were treated at hospitals with high volumes of angioplasty. RESULTS: There was no significant difference in mortality during hospitalization or long-term follow-up between patients in the thrombolytic-therapy group and those in the primary-angioplasty group (mortality during hospitalization, 5.6 percent and 5.5 percent, respectively; P=0.93; adjusted hazard ratio for the risk of death within three years after primary angioplasty, 0.95; 95 percent confidence interval, 0.8 to 1.2). There was also no significant difference in mortality between high-risk subgroups of patients in the two treatment groups. The rates of procedures and costs were lower among patients in the thrombolytic-therapy group both at the time of hospital discharge and after three years of follow-up (30 percent fewer coronary angiograms, 15 percent fewer coronary angioplasties, and 13 percent lower costs after three years of follow-up). CONCLUSIONS: In a community setting, we observed no benefit in terms of either mortality or the use of resources with a strategy of primary angioplasty rather than thrombolytic therapy in a large cohort of patients with acute myocardial infarction.

Angioplasty, Balloon, Coronary↗
PubMed1996

Influence of early prehospital thrombolysis on mortality and event-free survival (the Myocardial Infarction Triage and Intervention [MITI] Randomized Trial). MITI Project Investigators.

The Myocardial Infarction Triage and Intervention Trial of prehospital versus hospital administration of thrombolytic therapy markedly reduced hospital treatment times, but the 2 groups had similar outcomes. However, patients treated < 70 minutes from symptom onset had better short-term outcomes. The purpose of this study was to determine the long-term influence of very early thrombolytic treatment for acute myocardial infarction. A total of 360 patients were followed for vital status and cardiac-related hospital admissions over a period of 34 +/- 16 months. Patients enrolled in the trial had symptoms for < or = 6 hours, ST-segment elevation on the prehospital electrocardiogram, and no risk factors for serious bleeding. They received aspirin and recombinant tissue plasminogen activator either before or after hospital arrival. Primary end points in this study included long-term survival and survival free of death or readmission to the hospital for angina, myocardial infarction, congestive heart failure, or revascularization. Two-year survival was 89% for prehospital- and 91% for hospital-treated patients (p = 0.46). Event-free survival at 2 years was 56% and 64% for prehospital- and hospital-treated patients, respectively (p = 0.42). In patients treated < 70 minutes from symptom onset, 2-year survival was 98%, and it was 88% for those treated later (p = 0.12). Two-year event-free survival was 65% for patients treated early and 59% for patients treated later (p = 0.80). In this trial, poorer long-term survival was associated with advanced age, history of congestive heart failure, and coronary artery bypass surgery performed before the index hospitalization, but not with time to treatment.

Aged↗
PubMed1996

Comparison of presentation, treatment, and outcome of acute myocardial infarction in men versus women (the Myocardial Infarction Triage and Intervention Registry)

This study compared the presentation (symptoms and signs), treatment, and outcome of 1,097 consecutive patients (851 men and 246 women) from the Myocardial Infarction Triage and Intervention (MITI) Project Registry with confirmed acute myocardial infarction (AMI), all of whom were initially evaluated in the prehospital setting, met clinical criteria for possible thrombolysis, and were followed throughout their hospital course. Women were older than men and had a higher prevalence of known cardiovascular risk factors, including systemic hypertension and congestive heart failure. The presentation of AMI with respect to symptoms, delay, and hemodynamic and electrocardiographic findings was for the most part indistinguishable between mean and women. Women appeared "undertreated" early in the course of AMI and were half as likely as men to undergo acute catheterization, angioplasty, thrombolysis, or coronary bypass surgery (odds ratio 0.5 [0.3 to 0.7]). The risk for hospital mortality in women was almost twice that for men (odds ratio 1.95 [1.01 to 3.8]). Hospital mortality after AMI was also independently predicted by older age, early evidence of hemodynamic instability, and an intraventricular conduction abnormality on the initial electrocardiogram. Although similar in its presentation, AMI in women is not as aggressively treated, and results in a less favorable outcome than in men. Gender as well as nongender-specific risk factors are important in assessing risk and the likelihood of early intervention after AMI.

Aged↗
PubMed1996

Length of hospital stay after acute myocardial infarction in the Myocardial Infarction Triage and Intervention (MITI) Project registry.

OBJECTIVES: This study sought to identify current trends in length of stay in patients with an acute myocardial infarction and to evaluate which demographic, clinical, procedural and hospital-related factors explain the variation and reduction in length of stay observed during the study period. BACKGROUND: Hospital length of stay is an important contribution to cost of care. Previous studies of length of stay after acute myocardial infarction have been performed largely on administrative data bases and do not reflect current practice patterns. METHODS: We used univariate and multivariate models to evaluate which demographic, clinical and administrative factors influenced length of stay in 11,932 patients with acute myocardial infarction admitted to 19 Seattle-area hospitals between 1988 and 1994. RESULTS: Length of hospital stay decreased from (mean +/- SD) 8.5 +/- 8.2 to 6.0 +/- 5.8 days during the study period. Demographic and clinical characteristics known at the time of admission explained only 6% of variation in length of stay, whereas hospital complications, procedure use and type of admitting hospital explained an additional 27% of variation. The use of primary angioplasty and early diagnostic coronary angiography predicted a shorter length of stay; however, none of the measured variables explained the 29% reduction in length of stay that occurred between 1988 and 1994. CONCLUSIONS: Although hospital complications, procedure use and hospital characteristics are important predictors of length of hospital stay, none of these factors explains the 29% reduction in length of stay observed in postmyocardial infarction patients between 1988 and 1994. It is likely that unmeasured economic and administrative factors play important roles in influencing hospital length of stay.

Aged↗
PubMed1996

Future in vitro fertilization pregnancy potential of women with variably elevated day 3 follicle-stimulating hormone levels.

OBJECTIVE: To determine the IVF-ET pregnancy potential of women with variably elevated day 3 FSH. DESIGN: Cohort evaluation of 1,868 consecutive IVF-ET cycles January 1991 to December 1994. SETTING: University hospital infertility unit. PATIENTS: Four cohorts of couples were defined based on day 3 FSH determinations with an arbitrary threshold of 20 mIU/mL, only > or = 20 mIU/mL, always < 20 mIU/mL, current < 20 mIU/mL but one previous > or = 20 mIU/mL, and current < 20 mIU/mL but two or more previous > or = 20 mIU/mL (conversion factor to SI unit, 1.00). INTERVENTION: In vitro fertilization-embryo transfer. MAIN OUTCOME MEASURE: Fetal heart activity on luteal day 40 transvaginal ultrasound. RESULTS: No pregnancies occurred in 53 cycles with day 3 FSH only > or = 20 mIU/mL. In 1,750 women whose day 3 FSH levels were always < 20 mIU/mL, the pregnancy rate (PR) per cycle was 16.5%. In 54 cycles in which day 3 FSH was > or = 20 one time only, but < 20 mIU/mL during the treatment cycle, the PR was 5.6%. In 11 cycles where two or more previous FSH determinations were > or = 20 mIU/mL but with a current day 3 FSH < 20 mIU/mL, no pregnancies occurred. CONCLUSION: Our data leads us to the conclusion that day 3 FSH determination precede every IVF cycle and that cycles with FSH > or = 20 mIU/mL be canceled. It also suggests that women with two previous elevations of day 3 FSH be discouraged from future IVF cycles. The 5.6% pregnancy per cycle with one previously elevated FSH warrants extreme pessimism in discussion of further cycles.

Chorionic Gonadotropin↗
PubMed1995

Confounding variables affecting in vitro fertilization success: a decade of experience.

PURPOSE: To evaluate etiology of infertility, female age, ovarian response and stimulation protocol in affecting in vitro fertilization (IVF) success. METHODS: Retrospective analysis was used. Computer records of all 5209 cycles initiated in 2391 couples from February 1, 1984 to December 31, 1993 were analyzed. RESULTS: There were 644 intrauterine, 24 solely ectopic and 7 heterotopic pregnancies. Pregnancy rates increased with number of embryos transferred with a significant increase still found between transfer of three or four embryos. Multiple gestations also increased in association with an increasing number of embryos transferred. Pregnancy rates per cycle did not decline with repeated cycles. Reduced pregnancy rates were associated with a primary diagnosis of male infertility. Covariates associated with a better pregnancy rate were younger age of the female partner or higher peak preovulatory serum estradiol. Routine administration of GnRH-agonist was associated with a reduced cycle cancellation rate, an increase in oocytes retrieved and an improved pregnancy rate. CONCLUSIONS: Couples with male infertility and increased female age should be counselled regarding the reduced prognosis for success.

Age Factors↗