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W F Lewis

Publications and source records attributed to W F Lewis.

13 recordsLinked to original sources
PubMed1995

Estimated risk of transmission of the human immunodeficiency virus by screened blood in the United States.

BACKGROUND: In the United States, transmission of the human immunodeficiency virus (HIV) by blood transfusion occurs almost exclusively when a recently infected blood donor is infectious but before antibodies to HIV become detectable (during the "window period"). We estimated the risk of HIV transmission caused by transfusion on the basis of the window period associated with the use of current, sensitive enzyme immunosorbent assays and recent data on HIV incidence among blood donors. METHODS: We analyzed demographic and laboratory data on more than 4.1 million blood donations obtained in 1992 and 1993 in 19 regions served by the American National Red Cross, as well as the results of HIV-antibody tests of 4.9 million donations obtained in an additional 23 regions. RESULTS: We estimated that, in the 19 study regions, 1 donation in every 360,000 (95 percent confidence interval, 210,000 to 1,140,000) was made during the window period. In addition, it is estimated that 1 in 2,600,000 donations was HIV-seropositive but was not identified as such because of an error in the laboratory. We estimated that 15 to 42 percent of window-period donations were discarded because they were seropositive on laboratory tests other than the HIV-antibody test. When these results were extrapolated to include the additional 23 Red Cross service regions, there was a risk of one case of HIV transmission for every 450,000 to 660,000 donations of screened blood. If the Red Cross centers are assumed to be representative of all U.S. blood centers, among the 12 million donations collected nationally each year an estimated 18 to 27 infectious donations are available for transfusion. CONCLUSIONS: The estimated risk of transmitting HIV by the transfusion of screened blood is very small and nearly half that estimated previously, primarily because the sensitivity of enzyme immunosorbent assays has been improved.

Blood Banks↗
PubMed1994

The effectiveness of the confidential unit exclusion option.

BACKGROUND: The confidential unit exclusion (CUE) option is intended to reduce human immunodeficiency virus (HIV) transmission by excluding donors newly infected with HIV who have not yet developed HIV antibody (window-period donors); however, its efficacy in excluding window-period donors has not been evaluated. STUDY DESIGN AND METHODS: The use of the CUE option was studied among the donors of 3.7 million units at 18 American Red Cross blood services regions during 1991 and 1992 and among 322 previously HIV-1-seronegative donors who subsequently donated a seropositive unit between 1987 and 1990 at 40 United States blood centers. These seroconverting donors had previously been shown to be highly likely to donate during their window period. RESULTS: On the basis of data from these two populations, it was estimated that only 3 to 5 percent of units donated by window-period donors were not transfused because of the CUE option, that 0.4 percent of all donations were from donors who confidentially excluded their blood from transfusion, and that donors who confidentially excluded their blood were 21 times more likely to be HIV antibody-positive than donors who did not use the CUE option. It is estimated that, if all US blood centers used the CUE option, a total of 2 to 17 otherwise acceptable units donated by window-period donors would not be transfused annually. CONCLUSION: Although donors who confidentially exclude their blood from transfusion are 21 times more likely to have HIV antibody, the rarity of window-period donors and the infrequency of confidential exclusion by window-period donors cause the CUE option to have minimal impact on transfusion safety.

Acquired Immunodeficiency Syndrome↗
PubMed1987

A critical analysis of the use of the CFK equation in predicting COHb formation.

Fifteen healthy young males, nine at rest and six at exercise, were exposed to high transient levels of carbon monoxide (CO) to simulate the breathing environment measured in an armored vehicle during weapons firing. Depending on the dosage, the CO exposures raised the subjects' carboxyhemoglobin saturation (%COHb) from 1.7% to 17.3%. The measured %COHb levels compared favorably (regression coefficient, b = 1.04) to those predicted by the theoretical model of Coburn et al. When the application of this same model by a method proposed by NIOSH was used, however, a significant overprediction was found (b = 1.28). It appears that this overprediction results primarily from the omission of water vapor in the lungs when the inspired pressure of CO is considered, and to the use of incorrect values for alveolar ventilation. These results demonstrate the errors that may arise from the incorrect utilization of the equation by Coburn et al. and the effect that this may have upon the calculation of the limits for safe occupational exposure to CO.

Adult↗
PubMed1986

Hospital characteristics and the use of computer processing and abstract services. A logistic analysis.

The use of computer processing and abstract services by hospitals is in a state of continuing change. Although many hospitals subscribe to abstract or turnkey systems, others are leaving shared services to set up their own in-house systems. To better understand the relationship between hospital characteristics and the use of computer processing and/or abstract services, data from the AHA 1982 Special Survey on Selected Hospital topic were analyzed using logistic regression analysis. Hospital size, ownership, and region were clearly related to the use of computer processing and/or abstract services for processing discharge data. Teaching status was also related to the use of abstract services, although teaching status hospitals also reported more reliance on in-house computer processing. Hospitals located in SMSAs and belonging to chains reported a higher use of discharge abstract services, and hospitals with higher operating margins were more likely to use abstract services on an "off-line" or batch-processing basis. The significance of these findings and their implications for abstract services are discussed.

Abstracting and Indexing↗
PubMed1975

Effect of altitude exposure on platelets.

Since decompression from depth is known to produce a fall in platelet count, the effect of altitude decompression and high-altitude exposure on platelets was investigated. Sixteen subjects decompressed without hypoxia to 20,000 ft simulated altitude for two hours showed a significant (P less than 0.01) drop in circulating platelet count of approximately 10% for three days following decompression. Four of five subjects similarly exposed had a shortened autologous platelet survival compared to that prior to exposure. Subjects exposed to 9,800 ft and then 17,600 ft in a mountain environment showed a significant mean decrease in platelet count on day 2 of 7% and 25% respectively, which had returned to control by day 5. Nonhypoxic and hypoxic decompressed rabbits which received homologous chromium-51-labeled platelets had an increase in lung radioactivity compared with sea-level controls. It is postulated that altitude decompression produces platelet reductions similar to these seen after decompression from depth, and that platelets sequester in the pulmonary vascular bed.

Altitude↗
PubMedDate not supplied

Marital status and its relation to the use of short-stay hospitals and nursing homes.

Marital status has been associated with a wide variety of health indices and health practices. To better understand the relation of marital status to use of health facilities, discharge data from two surveys conducted by the National Center for Health Statistics--the 1979 National Hospital Discharge Survey and the 1976 National Nursing Home Survey--were examined by marital status, sex, age, diagnosed condition, and, for nursing home data, source of payment. For the four marital status categories considered in this analysis (married, never married, separated and divorced, and widowed), married and never married persons had the lowest overall discharge rates and widowed persons had the highest. Among men in each of the categories, those less than 45 years of age had the lowest rates, while never married and widowed men 45 and older generally had the highest rates. Among persons 45 years of age and older, the married-especially women-had the lowest rates and the never married-especially men-had the highest rates. A consistent finding was that, for never married persons, rates of use for both short-stay hospitals and nursing homes, as measured by discharge rates, increased to a greater degree with age than they did for the other marital groups. The possible reasons for the difference in use of health facilities by the different marital groups are discussed and the importance of marital status as a determinant of such use is stressed.

Adolescent↗