Use of the internal mammary artery graft and in-hospital mortality and other adverse outcomes associated with coronary artery bypass surgery.

BACKGROUND: There is clear evidence that patients having coronary artery bypass graft surgeries with an internal mammary artery (IMA) have better long-term survival. Some studies have suggested a short-term protective effect as well but, because older and sicker patients are less likely to receive an IMA graft, there has been concern that the apparent protective effect of the IMA on short-term mortality has been confounded by other risk factors. This study was intended to examine the independent effect of IMA grafts on in-hospital mortality while adjusting for patient and disease factors. METHODS AND RESULTS: We studied the use of the left IMA (LIMA) in 21 873 consecutive, isolated, first-time coronary artery bypass graft procedures from 1992 through 1999. A total of 87% of the patients received a LIMA graft. LIMA graft use was associated with a significantly decreased risk of mortality. The crude odds ratio for death (LIMA versus no LIMA) was 0.26 (95% confidence intervals, 0.22, 0.31; P:<0.001). LIMA grafts were protective across all major patient and disease subgroups. The odds ratios by subgroup ranged from 0.13 to 0.48. After adjustment for all major risk factors, the odds ratio for death was 0.40 (95% confidence intervals, 0.33, 0.48; P:<0.001). Rates of cerebrovascular accident, return to cardiopulmonary bypass, return to the operating room for bleeding, and mediastinitis or sternal dehiscence requiring surgery were also less in the LIMA group, although not significantly so. CONCLUSIONS: These data suggest that in addition to its well-documented patency and long-term beneficial effect, LIMA grafting has a strong protective effect on perioperative mortality.

Calcium and phosphorus supplementation of iron-fortified infant formula: no effect on iron status of healthy full-term infants.

One objective of this clinical trial was to determine whether calcium and phosphorus supplementation of infant formula affects the iron status of healthy full-term infants. One hundred three infants were randomly assigned to receive iron-fortified, cow milk-based infant formula (465 mg Ca and 317 mg P/L) or the same formula with added calcium glycerophosphate (1800 mg Ca and 1390 mg P/L) for 9 mo. Reported calcium intake for supplemented infants was about four times that of control infants, ranging from a mean of 1741 mg/d at baseline to 1563 mg/d at 9 mo. There was no difference by treatment group in mean or median change from baseline of serum ferritin, total-iron-binding capacity, erythrocyte protoporphyrin, or hematocrit at 4 and 9 mo after enrollment. Incidence of iron deficiency was similar for both groups and no infant developed iron deficiency anemia during the trial. This study indicates that the well-documented inhibitory effect of calcium and phosphorus on iron absorption is not clinically important in infants fed iron-fortified infant formula.

Randomized trial of calcium glycerophosphate-supplemented infant formula to prevent lead absorption.

BACKGROUND: Although additional dietary calcium is recommended frequently to reduce the risk of lead poisoning, its role in preventing lead absorption has not been evaluated clinically. OBJECTIVE: The objective was to determine the safety and to estimate the size of the effect of calcium- and phosphorus-supplemented infant formula in preventing lead absorption. DESIGN: One hundred three infants aged 3.5-6 mo were randomly assigned to receive iron-fortified infant formula (465 mg Ca and 317 mg P/L) or the same formula with added calcium glycerophosphate (1800 mg Ca and 1390 mg P/L) for 9 mo. RESULTS: There was no significant difference between groups in the mean ratio of urinary calcium to creatinine, serum calcium and phosphorus, or change in iron status (serum ferritin, total iron binding capacity). At month 4, the median (+/-SD) increase from baseline in blood lead concentration for the supplemented group was 57% of the increase for the control group (0.04 +/- 0.09 compared with 0.07 +/- 0.10 micromol/L; P = 0.039). This effect was attenuated during the latter half of the trial, with an overall median increase in blood lead concentration from baseline to month 9 of 0.12 +/- 0.13 micromol/L for the control group and 0.10 +/- 0.18 micromol/L for the supplemented group (P = 0.284). CONCLUSIONS: Supplementation did not have a measurable effect on urinary calcium excretion, calcium homeostasis, or iron status. The significant effect on blood lead concentrations during the first 4 mo was in the direction expected; however, because this was not sustained throughout the 9-mo period we cannot conclude that the calcium glycerophosphate supplement prevented lead absorption in this population.

Steroid treatment of laryngotracheitis: a meta-analysis of the evidence from randomized trials.

The use of adrenocorticoids to reduce the morbidity associated with laryngotracheitis (croup) remains controversial despite ten published reports of randomized trials involving 1,286 patients. To determine whether, viewed in aggregate, these studies demonstrate a significant benefit of steroid treatment for this disorder, a meta-analysis of the nine methodologically satisfactory trials was performed. Clinical improvement 12 and 24 hours posttreatment and incidence of endotracheal intubation were evaluated. For each end point, an estimate of the overall effect was obtained by calculating a typical odds ratio and 95% confidence interval. This analysis indicates that the use of steroids in children hospitalized with croup is associated with a significantly increased proportion of patients showing clinical improvement 12 hours (odds ratio = 2.25, 95% confidence interval = 1.66, 3.06) and 24 hours (odds ratio = 3.19, 95% confidence interval = 1.70, 5.99) posttreatment and a significantly reduced incidence of endotracheal intubation (odds ratio = 0.21, 95% confidence interval = 0.05, 0.84). Higher initial doses of steroid (greater than or equal to 125 mg of cortisone or greater than or equal to 100 mg of hydrocortisone) were associated with a larger proportion of patients improved 12 hours posttreatment than was seen with lower doses. These results support the use of steroids in the treatment of hospitalized children with croup and, in the absence of a randomized clinical trial of sufficient size, provide the most reliable estimate of the impact of steroid therapy on the morbidity associated with croup. In addition, the results of this meta-analysis may be used to estimate the number of subjects who would be required to conduct a randomized clinical trial of steroids for the treatment of croup.

Reverse first night effect in insomnia.

This study evaluates the reverse first night effect (FNE) in insomniacs. All insomniacs evaluated at the Dartmouth Sleep Disorders Center between 1975 and 1980 were studied if they met specific criteria (n = 89). First night effects were assessed using the following four variables: sleep efficiency, sleep latency, percentage of rapid eye movement (REM) sleep, and REM latency. The 20 subjects who showed the strongest normal FNE were compared with the 20 showing the strongest reverse FNE. The two groups were similar in age, sex, and most aspects of reported home sleep. They differed in their sleep on night 1, but on nights 2 and 3 their sleep was quite similar. Both groups overestimated their sleep latencies on night 1 (by subjective reports) but unlike the normal FNE group, the reverse FNE patients very accurately assessed their sleep latency on nights 2 and 3. Reverse FNE patients had significantly higher scores than normal FNE patients on the Minnesota Multiphasic Personality Inventory (MMPI) K (defensiveness, guardedness) and Pa (paranoia) scales, and they were less depressed, marginally less anxious, and somewhat more sensation-seeking and more susceptible to boredom. This study concluded that evaluations using only 1 night in the laboratory may be missing the larger picture of a patient's insomnia. When data from only 1 laboratory night are available for an insomniac, care should be taken with the label of "subjective complaint without objective findings" in patients who are defensive, guarded, and sensation-seeking.

Impact of dyspnea and physiologic function on general health status in patients with chronic obstructive pulmonary disease.

STUDY OBJECTIVE: To examine the relationship among clinical dyspnea ratings, physiologic pulmonary function, and general health status in symptomatic patients with chronic obstructive pulmonary disease (COPD). DESIGN: Observational data collected at a baseline state. SETTING: Outpatient pulmonary disease clinics at a university hospital and two VA medical centers. PATIENTS: One hundred ten male patients with COPD with no significant comorbidity were recruited. MEASUREMENTS AND RESULTS: Clinical ratings of dyspnea were measured by the multidimensional baseline dyspnea index (BDI). Pulmonary function tests included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximal inspiratory mouth pressure (PImax). General health status was assessed with the Medical Outcomes Study short-form survey, which consists of 20 questions that cover six health components. The mean age of the patients was 67 +/- 8 yr (+/- SD). The mean value for FVC was 2.84 +/- 0.84 L (68 +/- 18 percent of predicted), for FEV1 was 1.28 +/- 0.59 L (44 +/- 17 percent of predicted), and for PImax was 59.0 +/- 25.0 cm H2O. The BDI score and PImax were significantly correlated with five of the six components of general health status. Only three of the six components of general health were significantly correlated with FEV1 as percent predicted (rs value range, 0.30 to 0.44) and with FVC as percent predicted (rs value range, 0.25 to 0.33). Statistical comparisons showed that the BDI score had significantly higher correlations than FVC (percent predicted), FEV1 (percent predicted), and PImax values with physical functioning and role functioning. Multiple linear regression analysis showed that the BDI score was the only statistically significant predictor of role functioning, mental health, and health perceptions for general health status, whereas both the BDI score and FEV1 (percent predicted) were independent predictors of physical functioning and social functioning. CONCLUSION: Dyspnea ratings influence and predict general health status to a greater extent than do physiologic measurements in symptomatic patients with COPD. A shift in focus from the pathophysiology of disease to assessment and relief of symptoms may provide more meaningful benefits for the individual patient in terms of quality of life. This consideration requires that health-care providers use available measuring tools in clinical practice to quantify symptoms, as well as overall health status.

Changes in patients undergoing coronary artery bypass grafting: 1987-1990. Northern New England Cardiovascular Disease Study Group.

A prospective study of 7,590 consecutive patients undergoing isolated coronary artery bypass grafting at five medical centers in Maine, New Hampshire, and Vermont between July 1987 and December 1990 assessed changes in patient characteristics over time. Variables included age, sex, surgical priority, ejection fraction, left ventricular end-diastolic pressure, and left main coronary artery stenosis of 90% or greater. Trends were assessed for each variable and for predicted mortality using linear regression. The mean age increased significantly, whereas ejection fraction decreased. The percentage of urgent cases increased, whereas the elective cases became less frequent. No changes were observed in the percentages of emergent cases, female patients, or patients with severe left main coronary artery disease. The predicted in-hospital mortality rose significantly from 4.2% to 5.2% (p < 0.001). The increase in urgent surgical intervention was the most substantial contributor. Subgroup analyses did not support a systematic misclassification of elective patients into the urgent group. This study demonstrates that the characteristics of the cohort of patients undergoing coronary artery bypass grafting changed substantially from 1987 to 1990. These changes should be considered when interpreting surgical outcomes.

In-hospital outcomes of off-pump versus on-pump coronary artery bypass procedures: a multicenter experience.

BACKGROUND: Concern about the possible adverse effects of the cardiopulmonary bypass (CPB) pump and advances in retractors and operative techniques to access all coronary segments have resulted in increased interest in off-pump coronary artery bypass (OPCAB) procedures. Four of the Northern New England Cardiovascular Disease Study Group centers initiated OPCAB programs in 1998. We compared the preoperative risk profiles and in-hospital outcomes of patients done off-pump with those done by conventional coronary artery bypass (CCAB) with CPB. METHODS: Between 1998 and 2000, 1,741 OPCAB and 6,126 CCAB procedures were performed at these four medical centers. Minimally invasive direct coronary artery bypass grafting procedures were excluded. Data were available for patient and disease risk factors, extent of coronary disease and adverse in-hospital outcomes. RESULTS: The OPCAB and CCAB groups were somewhat different in their preoperative patient and disease characteristics. The OPCAB patients were more likely to be female and to have peripheral vascular disease. The CCAB patients were more likely to have an ejection fraction less than 0.40 and be urgent or emergent at operation. However, overall predicted risk of in-hospital mortality, based on preoperative factors, was similar in the OPCAB and CCAB groups; the mean predicted risk was 2.6% (p = 0.567). Crude rates of mortality (2.54% OPCAB versus 2.57%, CCAB), intraoperative or postoperative stroke (1.33% versus 1.82%), mediastinitis (1.10% versus 1.37%), and return to the operating room for bleeding (3.46% versus 2.93%) did not differ significantly. The OPCAB patients did have a statistically significant reduction in the need for intraoperative or postoperative intraaortic balloon pump support (2.31% versus 3.41%; p = 0.023) and in the incidence of postoperative atrial fibrillation (21.21% versus 26.31%; p < 0.001). Adjustment for preoperative risk factors and extent of coronary disease did not substantially change the crude results. Median postoperative length of stay was significantly shorter (5 days versus 6 days, p < 0.001) for OPCAB patients than for CCAB patients. CONCLUSIONS: This multicenter study showed that patients having OPCAB are not exposed to a greater risk of short-term adverse outcomes. These data also provided evidence that patients having OPCAB have significantly lower need for intraoperative or postoperative intraaortic balloon pump, lower rates of postoperative atrial fibrillation, and a shorter length of stay.

Effect of preoperative aspirin use on mortality in coronary artery bypass grafting patients.

BACKGROUND: Discontinuing aspirin use in patients before coronary artery bypass grafting (CABG) has focused on bleeding risks. The effect of aspirin use on overall mortality with this procedure has not been studied. METHODS: We performed a case patient-control patient study of the 8,641 consecutive isolated CABG procedures performed between July 1987 and May 1991 in Maine, New Hampshire, and Vermont. Patients included all 368 deaths. Each case patient was paired with approximately two matched survivors (control patients). Aspirin use was defined by identification of ingestion within 7 days before the operation. RESULTS: CABG patients using preoperative aspirin were less likely to experience in-hospital mortality in univariate (odds ratio [OR] = 0.73, 95% confidence interval [0.54, 0.97]) and multivariate [OR = 0.55, (0.31, 0.98)] analysis compared to nonusers. No significant difference was seen in the amount of chest tube drainage, transfusion of blood products, or need for reexploration for hemorrhage between patients who did and did not receive aspirin. CONCLUSIONS: Preoperative aspirin use appears to be associated with a decreased risk of mortality in CABG patients without significant increase in hemorrhage, blood product requirements, or related morbidities.

Decreasing mortality for aortic and mitral valve surgery in Northern New England. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Although numerous reports have documented declining mortality rates associated with coronary artery bypass surgery in recent years, it is unknown whether similar trends have occurred with valve surgery during this time. METHODS: We conducted a regional, prospective study to assess trends in patient casemix and in-hospital mortality rates over time with aortic valve replacement (AVR), mitral valve replacement (MVR), and mitral valve repair. Data were collected from all patients undergoing AVR (n = 2,596), MVR (n = 759), or mitral valve repair (n = 522) in Northern New England between January 1992 and December 1997. Logistic regression was used to identify significant predictors of in-hospital mortality and to calculate risk-adjusted mortality rates. RESULTS: For AVR, the trend in patient casemix was toward increased risk with increases in patient age and in the proportion of patients with: body surface area less than 1.7, diabetes, coronary artery disease, and prior valve surgery. A decrease was noted in the proportion of patients undergoing additional surgical procedures. For MVR, patient risk improved over the time period with fewer female patients and fewer patients with coronary artery disease. For mitral valve repair patient risk increased over the time period with increases in the proportion of patients with coronary artery disease, diabetes, and whose surgical priority was classified as urgent. In addition, there was a borderline significant increase in the proportion of mitral valve repair patients in New York Heart Association class IV preoperatively. Risk-adjusted mortality decreased 44% from 9.3% in 1992 through 1993 to 5.3% in 1996 through 1997 for patients undergoing AVR (p = 0.01) and decreased 53% from 13.6% in 1992 through 1993 to 8.2% in 1996 through 1997 for patients undergoing MVR (p = 0.01). We observed a statistically insignificant increase in risk-adjusted mortality over the time period for patients undergoing mitral valve repair (from 3.6% in 1992 through 1993 to 5.0% in 1996 through 1997; p = 0.34). CONCLUSIONS: Significant improvement in mortality rates with valve replacement was observed in northern New England during this time period. This improvement persisted following adjustment for changes in patient casemix over this time. These trends mirror improvements in mortality with other cardiac surgical interventions that have been observed in recent years in our region and nationally.

Results of a regional study of modes of death associated with coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: It is well known that surgeon-specific in-hospital mortality rates for coronary artery bypass grafting vary, but this aggregate measure does not suggest specific opportunities for improvement. METHODS: We performed a regional prospective study of 8,641 consecutive patients undergoing isolated coronary artery bypass grafting by all of the 23 cardiothoracic surgeons practicing in northern New England during the study period. Mode of death was assigned by an end points committee using predetermined definitions. Surgeons were ranked according to risk-adjusted mortality rates and grouped in terciles, and cause-specific mortality rates were determined. RESULTS: The mortality rate was 3.3% in the lowest surgeon mortality tercile and 5.8% in the highest tercile. Fatal heart failure accounted for 80.0% of the difference in aggregate mortality rates, ranging from 1.9% in lowest surgeon mortality tercile to 4.0% in the highest tercile (p < 0.001). Rates of other causes did not differ significantly across surgeon mortality terciles. Differences in rates of fatal heart failure could not be explained by differences in preoperative left ventricular dysfunction or other patient characteristics. CONCLUSIONS: Most of the difference in observed mortality rates across surgeons is attributable to differences in rates of heart failure.

Improved in-hospital mortality in women undergoing coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Few studies have examined the changes in in-hospital mortality for women over time. We describe the changing case mix and mortality for women undergoing coronary artery bypass grafting (CABG) from 1987 to 1997 in northern New England. METHODS: Data were collected on 8,029 women and 21,139 men undergoing isolated CABG. The study consisted of three time periods (1987 to 1989, 1990 to 1992, and 1993 to 1997) to account for regional efforts to improve quality of care that occurred during 1990 to 1992. RESULTS: Compared with 1987 to 1989, women undergoing CABG in 1993 to 1997 were older, had poorer ventricular function, and more often required urgent or emergency operations. The crude and adjusted mortality rates for both women and men decreased significantly over time. The absolute magnitude of the change in adjusted rates was greater for women (3.1%) than for men (1.5%). Although women represented only 28% of the study population, the decrease in their mortality accounted for 44% of the total decrease in adjusted mortality during the study period. CONCLUSIONS: Over the last decade there has been a marked decrease in CABG mortality for women, despite a worsening case mix.

Lowest hematocrit on bypass and adverse outcomes associated with coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Cardiac surgery patients' hematocrits frequently fall to low levels during cardiopulmonary bypass. METHODS: We investigated the association between nadir hematocrit and in-hospital mortality and other adverse outcomes in a consecutive series of 6,980 patients undergoing isolated coronary artery bypass graft surgery. The lowest hematocrit during cardiopulmonary bypass was recorded for each patient. Patients were divided into categories based on their lowest hematocrit. Women had a lower hematocrit during bypass than men but both sexes are represented in each category. RESULTS: After adjustment for preoperative differences in patient and disease characteristics, the lowest hematocrit during cardiopulmonary bypass was significantly associated with increased risk of in-hospital mortality, intra- or postoperative placement of an intraaortic balloon pump and return to cardiopulmonary bypass after attempted separation. Smaller patients and those with a lower preoperative hematocrit are at higher risk of having a low hematocrit during cardiopulmonary bypass. CONCLUSIONS: Female patients and patients with smaller body surface area may be more hemodiluted than larger patients. Minimizing intraoperative anemia may result in improved outcomes for this subgroup of patients.

A meta-analysis of randomized trials of fish oil in prevention of restenosis following coronary angioplasty.

The efficacy of fish oil in decreasing restenosis following percutaneous transluminal coronary angioplasty (PTCA) remains controversial despite seven published reports of randomized trials involving 951 patients. We performed a meta-analysis to determine whether these trials, viewed in aggregate, demonstrate a significant benefit. We evaluated rates of restenosis two to 12 months after PTCA and calculated an estimate of the overall effect and 95% confidence interval (CI). The typical odds ratio (treatment versus control) was 0.71 (95% CI 0.54, 0.94), P = 0.016 (two-tailed). The data show a strong and highly significant (P less than .0001) relationship between daily fish oil dose and gastrointestinal side effects. While compatible with a small to moderate benefit of fish oil on rates of restenosis, these results require confirmation in a randomized clinical trial large enough to distinguish reliably between a clinically meaningful benefit and a null result.

Detection of hepatotoxicity associated with methotrexate therapy for psoriasis.

To determine whether liver function tests and clinical and demographic information would predict methotrexate-associated hepatotoxicity, we identified 78 patients who had undergone 147 liver biopsies associated with methotrexate therapy for psoriasis. The joint sensitivity of aspartate aminotransferase, alkaline phosphatase, and total bilirubin values in detecting abnormal results from a biopsy specimen obtained after treatment was .86; the predictive value of negative test results was .93. A logistic regression model significantly predicted the presence of abnormal (grade III or higher) liver biopsy specimen results. The concordance index was .92 (perfect, 1.0). Regression coefficients may be used along with information from a specific patient to calculate the predicted probability of an abnormal result from a liver biopsy specimen after treatment. We conclude that this multivariate risk estimation model significantly predicts the likelihood of positive findings from liver biopsy specimens in this patient population. The clinical use of this model awaits further validation.

Comparison of dyspnea ratings during submaximal constant work exercise with incremental testing.

PURPOSE: The purpose of this study was to determine whether dyspnea ratings would be similar during submaximal (as used for training) and incremental (as used in testing) exercise at specific intensities in patients with chronic obstructive pulmonary disease (COPD). METHODS: We studied 20 patients with COPD. Age was 66 +/- 9 yr (mean +/- SD); FEV1 was 43 +/- 14% pred. At Visit 1 patients provided dyspnea ratings (0 to 10 scale) each minute during incremental exercise on the cycle ergometer. At Visit 2 patients rated dyspnea during production of submaximal exercise for 10 min at two intensities. RESULTS: Peak oxygen consumption (VO2) was 13.9 +/- 3.2 mL.kg-1.min-1. At visit 2 VO2 was stable, but dyspnea ratings increased slightly. Dyspnea ratings (2.0 +/- 1.2) during submaximal exercise were higher than during incremental exercise (1.1 +/- 0.7) at 55 +/- 8% of peak VO2 (P = 0.02) but were similar (4.3 +/- 1.5 vs 3.9 +/- 1.5) at 77 +/- 8% of peak VO2 (P = 0.40). CONCLUSIONS: In patients with COPD, dyspnea ratings were similar during steady state compared with equivalent levels of incremental exercise at a "high" intensity, but were slightly higher at the "low" exercise intensity. These data support the potential use of dyspnea ratings obtained during incremental exercise as a target for exercise training in patients with respiratory disease.

A physician-completed patient registry system: pilot results for unstable angina in the elderly. The Northern New England Cardiovascular Disease Study Group and the Dartmouth Primary Care COOP.

OBJECTIVE: For many common conditions, such as unstable angina pectoris (UAP) in the elderly, the course of the disease and the influence of treatments on outcome need to be better described. In this report the authors demonstrate how a simple pocket-sized card system can be used by busy clinicians to identify patient cohorts and follow the courses of their illnesses. DESIGN AND SETTING: Twelve university-based and 12 rural clinicians enrolled consecutive patients over the age of 64 with UAP. One week and six weeks after patient enrollment the physicians described treatments, diagnoses, and patient outcomes. RESULTS: The median age of the 76 patients was 73 years. Within one week of enrollment for UAP, ten (13%) suffered myocardial infarctions or died; by six weeks this adverse event rate was 26%. The presence of three or more clinical criteria for UAP (odds ratio 9.9; 95% CI 2.4-41.5) and "ST changes" by electrocardiography (odds ratio 9.5; 95% CI 2.5-35.6) were strongly associated with death or myocardial infarction within a week after enrollment. CONCLUSION: These findings suggest that the use of a clinician-completed patient registry will allow designation of clinically important high- and low-risk UAP. A registry system such as that described here may be useful for the initial evaluation of treatment and outcomes of illness.

Changes in dyspnea, health status, and lung function in chronic airway disease.

The purpose of this study was to examine longitudinal changes in clinical parameters in patients with chronic obstructive pulmonary disease (COPD). We postulated that progressive dyspnea and decline in lung function over time would influence or impact patient's health status. Clinical ratings of dyspnea, general health status, and physiologic lung function were measured every 6 mo over a 2-yr period in an original group of 110 male patients with stable but symptomatic COPD and no significant comorbidity. At enrollment, age was 67 +/- 8 yr (mean +/- SD), forced expiratory volume in one second (FEV1) was 1.28 +/- 0.59 I (44 +/- 17% of predicted), and forced vital capacity (FVC) was 2.84 +/- 0.84 I (68 +/- 18% of predicted). A total of 34 patients "dropped out" because of death (n = 20), relocation (n = 7), and other reasons (n = 7). Dyspnea was measured using the transition dyspnea index (TDI), which represented changes from the baseline state; general health status was measured using the Medical Outcomes Study (MOS) 20-item short-form survey; physiologic lung function was assessed by spirometry (FVC and FEV1) and inspiratory muscle strength (PImax). Statistical analyses were performed using all available data for each patient, including results until the time at which patients died or were lost to follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of breathlessness during exercise in asthmatics. Predictor variables, reliability, and responsiveness.

The purpose of this study was to determine the predictor variables for breathlessness and to investigate the criteria of reliability and responsiveness for measuring breathlessness during progressive, incremental exercise on the cycle ergometer. We studied a heterogeneous group of patients with stable asthma (mean +/- SEM age, 46 +/- 4 yr) for four visits at weekly intervals. Predictor variables were determined at the first visit. Nine independent physiologic variables were obtained at each minute during exercise; the Borg rating of breathlessness (range 0 to 10) was used as the dependent variable. The regression model relating the physiologic parameters to the Borg rating of breathlessness was highly significant (model F = 43.4; p = 0.0001). Backward elimination selected the strongest predictors of the Borg rating: peak inspiratory flow (VI); tidal volume (VT)/FVC; frequency of respiration (f); and peak inspiratory mouth pressures (Pm). These four variables explained 63% of the variance in the rating of dyspnea. Each of the four variables exhibited a linear relationship with the Borg rating. Test-retest reliability was assessed by comparing results at the first and second visits. Individual slopes (except for VT/FVC) and intercepts for the four predictor variables versus Borg ratings were highly reliable. The slope for work intensity (watts) and Borg ratings, but not the intercept, was highly reliable. Responsiveness was evaluated by randomly administering inhaled methacholine or inhaled metaproterenol, alternately, at the third and fourth visits to induce acute changes in lung function before exercise.(ABSTRACT TRUNCATED AT 250 WORDS)