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Biomedical subjects

K A Adal

Publications and source records attributed to K A Adal.

28 records · Page 2Linked to original sources
PubMed1995

Preventing pneumococcal bacteremia in patients at risk. Results of a matched case-control study.

BACKGROUND: Three randomized controlled trials of the effectiveness of pneumococcal vaccine in elderly and chronically ill adults in the United States have failed to show significant protective efficacy during 44,213 person-years of follow-up. Case-control studies have greater statistical power to detect significant prevention of rare diseases such as pneumococcal bacteremia, but they also have a greater susceptibility to bias, necessitating consistent results from multiple studies. Three case-control studies at two different universities have shown prevention of systemic infection, but another study found no benefit. METHODS: Patients with pneumococcal bacteremia who were at least 2 years old and had chronic illness indicating the need for pneumococcal vaccine, or who were at least 65 years old were compared with matched control subjects for frequency of prior vaccination. Matching variables included date of admission, age, sex, race, type and duration of chronic illness serving as the major vaccine indication, number of vaccine indications and number of medical hospitalizations since licensure of the pneumococcal vaccine in 1978, and type of primary medical care. RESULTS: Pneumococcal vaccination was documented in the records of six (7%) of 85 cases and 26 (17%) of 152 control subjects, suggesting 81% efficacy in conditional logistical regression analysis (95% confidence interval, 34% to 94%, P = .008). CONCLUSIONS: Four case-control studies at three universities have now demonstrated significant protective efficacy of pneumococcal vaccine for preventing pneumococcal bacteremia. The development of antibiotic-resistant Streptococcus pneumoniae indicates an urgent need for an increased rate of vaccination among high-risk patients and for the development of more immunogenic conjugate vaccines that may enhance efficacy among elderly and immunocompromised patients as well as infants.

Adolescent↗
PubMed1994

The use of high-efficiency particulate air-filter respirators to protect hospital workers from tuberculosis. A cost-effectiveness analysis.

BACKGROUND: After outbreaks of multidrug-resistant tuberculosis, the Centers for Disease Control and Prevention proposed the use of respirators with high-efficiency particulate air filters (HEPA respirators) as part of isolation precautions against tuberculosis, along with a respiratory-protection program for health care workers that includes medical evaluation, training, and tests of the fit of the respirators. Each HEPA respirator costs between $7.51 and $9.08, about 10 times the cost of respirators currently used. METHODS: We conducted a cost-effectiveness analysis using data from the University of Virginia Hospital on exposure to patients with tuberculosis and rates at which the purified-protein-derivative (PPD) skin test became positive in hospital workers. The costs of a respiratory-protection program were based on those of an existing program for workers dealing with hazardous substances. RESULTS: During 1992, 11 patients with documented tuberculosis were admitted to our hospital. Eight of 3852 workers (0.2 percent) had PPD tests that became positive. Five of these conversions were believed to be due to the booster phenomenon; one followed unprotected exposure to a patient not yet in isolation; the other two occurred in workers who had never entered a tuberculosis isolation room. These data suggest that it will take more than one year for the use of HEPA respirators to prevent a single conversion of the PPD test. Assuming that one conversion is prevented per year, however, it would take 41 years at out hospital to prevent one case of occupationally acquired tuberculosis, at a cost of $1.3 million to $18.5 million. CONCLUSIONS: Given the effectiveness of currently recommended measures to prevent nosocomial transmission of tuberculosis, the addition of HEPA respirators would offer negligible protective efficacy at great cost.

Cost-Benefit Analysis↗
PubMed1994

Mycobacterium tuberculosis transmission rates in a sanatorium: implications for new preventive guidelines.

BACKGROUND: In 1990, the Centers for Disease Control and Prevention recommended substituting dust-mist particulate respirators for simple isolation masks in acid-fast bacillus isolation rooms, reasoning that air leaks around the simple masks could result in a higher rate of purified protein derivative skin-test conversion. In 1993, a Centers for Disease Control and Prevention draft guideline proposed that high-efficiency particulate air filter respirators be used instead of dust-mist particulate respirators. Epidemiologic data were not available to assess the importance of these changes or their cost-effectiveness. METHODS: The University of Virginia was affiliated with a tuberculosis hospital from 1979 until 1987. We surveyed physicians who had served as residents in internal medicine during this period regarding purified protein derivative skin-test history. duration of work at the tuberculosis sanatorium, and any history of unprotected exposures to patients with active pulmonary or laryngeal tuberculosis. Patients with active tuberculosis at the sanatorium were isolated in negative-pressure rooms with UV lights. Physicians wore simple isolation masks in these rooms. RESULTS: Responses were received from 83 former resident physicians. Fifty-two physicians had worked on the tuberculosis wards for a total of 420 weeks, with no subsequent skin-test conversions (95% CI 0 to 1 conversion/8 physician-years). CONCLUSIONS: These data document a low risk of occupational transmission of Mycobacterium tuberculosis to physicians who wear simple isolation masks in negative-pressure ventilation rooms with UV lights. This low rate predicts that the additional protective efficacy and cost-effectiveness of the more expensive high-efficiency particulate air filter respirators and the respiratory protection program will be low.

Hospitals, Special↗