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K J Lui

Publications and source records attributed to K J Lui.

51 records · Page 3Linked to original sources
PubMed1988

A model-based approach to characterize the incubation period of paediatric transfusion-associated acquired immunodeficiency syndrome.

Traditional statistics, such as the average, currently provide a misleading statistical description of the incubation periods of paediatric transfusion-associated acquired immunodeficiency syndrome (TA-AIDS). Two types of length-biased sampling, left censoring and right censoring, occur in the 37 cases diagnosed before 1986 and reported to the Centers for Disease Control by 15 September 1986. To correct for these problems, we propose a truncated Weibull distribution with use of a maximum likelihood technique. This approach suggests that the mean incubation period of paediatric TA-AIDS cases is 2.4 years with a 90 per cent confidence interval ranging from 1.5 years to 7.2 years. The mode is 1.25 years. These estimates are much shorter than those recently published for adults, therefore the success of TA-AIDS prevention strategies may be seen sooner in the paediatric age group.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Estimation of sample sizes in case-control studies with multiple controls per case: dichotomous data.

In planning case-control studies with matched sets, the calculation of exact sample sizes is difficult, because this calculation depends on some nuisance parameters that are usually unknown in practice. Using the Pitman efficiency of Miettinen's test relative to McNemar's test, Schlesselman and Stolley (Case-control studies: design, conduct, analysis. Oxford: Oxford University Press, 1982:144-70) derived an approximate sample size formula which requires the assumption that the difference in exposure rates between cases and controls is small. Furthermore, on the basis of an assumption similar to that used in Schlesselman and Stolley's approach, Taylor (Stat Med 1986;5:29-36) proposed another approximation formula. In this paper, an alternative and explicit formula that does not require the exposure difference to be small between case and control groups has been derived. Monte Carlo studies are given for comparing the accuracy of these three procedures. The results indicate that when odds ratios of exposure between cases and controls are small (less than or equal to 4) and there is more than one matched control per case, the formula derived in this paper seems to be the best. When odds ratios are large (greater than or equal to 5), however, Taylor's more conservative estimate is recommended, unless the exposure prevalence in the general population is large (0.9).

Epidemiologic Methods↗
PubMed1988

The roles of vaccination and amantadine prophylaxis in controlling an outbreak of influenza A (H3N2) in a nursing home.

An outbreak caused by influenza A/Philippines/2/82 (H3N2)-like viruses occurred in a partially vaccinated nursing home population in January 1985. During the first six days of the outbreak, 14 (25%) of 55 residents developed influenzalike illness. The risk of illness was most strongly associated with undetectable levels of antibody against the epidemic strain, with unvaccinated case-patients having more severe illnesses and a higher rate of hospitalization than vaccinated case-patients (5/8 vs 0/6). During the period of amantadine hydrochloride prophylaxis (100 mg/d) from days 7 to 35, only two (5%) of the remaining 41 residents became ill, even though 11 (27%) had no detectable antibody. Serum amantadine levels obtained on day 35 ranged from 117 to 737 ng/mL (mean 309 ng/mL), similar to therapeutic levels documented in younger adults who have taken the standard regimen of 200 mg/d; there were few clinically significant side effects. These findings illustrate the benefits of influenza vaccination and support the use of amantadine hydrochloride at a dosage of 100 mg daily for outbreak control among elderly persons.

Adult↗
PubMed1987

Impact of influenza epidemics on mortality in the United States from October 1972 to May 1985.

Baseline levels of mortality in the United States in the absence of influenza epidemics were estimated using cyclical regression models applied to national vital statistics from October 1972 to May 1985. Models were developed by age and by region. Results from 1983 to 1985 are preliminary. More mortality than predicted by the theoretical baseline occurred during nine influenza seasons. Epidemics with high morbidity in children and young adults occurred in 1976/77 and 1978/79. Regional differences in the impact of influenza occurred occasionally. Total influenza-associated excess mortality in six epidemics from the winters of 1972/73 to 1980/81 was about 200,000. About 80-90 per cent of excess mortality occurred in persons over 64 years old.

Aged↗
PubMed1986

A model-based approach for estimating the mean incubation period of transfusion-associated acquired immunodeficiency syndrome.

The incubation period, representing the interval between the date of exposure and the date of diagnosis, can be firmly ascertained in transfusion-associated cases of acquired immunodeficiency syndrome (AIDS). However, because the observation period of all transfusion-infected persons may be short compared with the average incubation period for AIDS, many cases with long incubation periods have not yet been diagnosed. Thus, the simple average of 2.6 years tends to underestimate the true mean. To correct for this underestimation bias, we assumed that the underlying distribution of the incubation periods is a member of a broad class of probability densities. Then, by maximum likelihood techniques, the mean incubation period for transfusion-associated AIDS was estimated to be 4.5 years, with the 90% confidence interval ranging from 2.6 to 14.2 years. The long incubation period has important consequences for infected individuals and implications for public health intervention and prevention policy.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Amantadine prophylaxis during an institutional outbreak of type A (H1N1) influenza.

In January 1984, an outbreak of influenza caused by A/Victoria/7/83-like virus, a new H1N1 variant, occurred in an institution for mentally handicapped children and adults. During the first 18 days of the outbreak, 35 (81%) of 43 residents in two housing modules became ill, nearly all of whom had received influenza vaccine the previous autumn. Amantadine hydrochloride prophylaxis was initiated in two other housing modules and was continued for 28 days. While factors influencing the risk of introduction and secondary spread of influenza virus were comparable in all four modules, only ten (16%) of 63 residents who received amantadine were infected, only one of whom became symptomatic. Most side effects associated with amantadine were mild, but residents with active, preexisting major-motor seizure disorders demonstrated an increase in seizure activity compared with the previous eight-month period; those who took the maximum daily dose of amantadine hydrochloride (200 mg) and those who were also taking anticonvulsants other than phenobarbital were at highest risk.

Adolescent↗
PubMed1984

Outbreak of paralytic poliomyelitis, Taiwan.

Taiwan had been free of major poliomyelitis outbreaks since 1975, but from May 29 to Oct 26, 1982, 1031 cases of type 1 paralytic poliomyelitis were reported to the Taiwan health authorities. Before the outbreak approximately 80% of infants had received at least 2 doses of trivalent oral poliovaccine (OPV) by their first birthday. Of the 86% of poliomyelitis patients whose vaccination status was known 65% had not had poliovaccine, 19% had received one dose, 8% had received two doses, and 8% had received three or more doses. Vaccine efficacy was calculated to be 82% after one dose, 96% after two doses, and 98% after three or more doses. Failure to vaccinate rather than vaccine failure was the most important risk factor in this outbreak. A child who had not had any vaccine was 80 times more likely to become a case than one who had received three or more doses of poliovaccine, independent of sanitation facilities at home. A child was 5 times more likely to become a case if he received water from non-municipal rather than municipal sources. Furthermore, for children who received municipal water, the risk was doubled if the family shared a toilet with at least one other family. This outbreak shows that major epidemics can occur in areas that have high overall community vaccination levels. Identification and vaccination of subpopulations with low coverage is essential for the control of poliomyelitis.

Adolescent↗
PubMed1984

Acquired immunodeficiency syndrome (AIDS) associated with transfusions.

Of 2157 patients with the acquired immunodeficiency syndrome (AIDS) whose cases were reported to the Centers for Disease Control by August 22, 1983, 64 (3 per cent) with AIDS and Pneumocystis carinii pneumonia had no recognized risk factors for AIDS. Eighteen of these (28 per cent) had received blood components within five years before the onset of illness. These patients with transfusion-associated AIDS were more likely to be white (P = 0.00008) and older (P = 0.0013) than other patients with no known risk factors. They had received blood 15 to 57 months (median, 27.5) before the diagnosis of AIDS, from 2 to 48 donors (median, 14). At least one high-risk donor was identified by interview or T-cell-subset analysis in each of the seven cases in which investigation of the donors was complete; five of the six high-risk donors identified during interview also had low T-cell helper/suppressor ratios, and four had generalized lymphadenopathy according to history or examination. These findings strengthen the evidence that AIDS may be transmitted in blood.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

The use of the binomial distribution in establishing an association between high-risk donors and transfusion-associated AIDS.

In the first seven cases of transfusion-associated acquired immunodeficiency syndrome (TA-AIDS) with completion of blood donor investigations, there was identification of at least one person (a high-risk donor--HRD) in each donor set who might have transmitted the disease. Using three definitions of an HRD, we estimated the prevalence of HRDs in the overall donor population and used the binomial distribution to calculate the probabilities of finding at least the observed numbers of donor sets with one or more HRDs. These probabilities--0.028, 0.007 and 0.014, respectively--allowed us to reject the null hypothesis that the number of cases of TA-AIDS exposed to an HRD was not greater than that expected by chance, based on the total number of donors to which each case was exposed and the estimated proportion of HRDs in the overall donor population. We concluded that there was a statistically significant association between HRDs and TA-AIDS.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Reducing ultraviolet radiation exposure in children.

BACKGROUND: Project SUNWISE evaluated the effectiveness of a multicomponent intervention in reducing children's ultraviolet radiation (UVR) exposure. METHODS: Across four YMCAs, 48 aquatics classes (N = 169 children, mean age = 7) were randomly assigned to either the intervention or the control condition. The 6-week intervention included a UVR reduction curriculum presented at poolside by aquatics instructors and home-based activities for children and their parents. Outcome measures were (a) tanness-associated skin color dimensions assessed with a colorimeter, (b) specific daily solar protection behaviors of children as reported by parents, and (c) general solar protection behaviors. RESULTS: Controlling for intraclass clustering in all analyses, at posttest, no statistically significant between-group differences were found in tanness, daily solar protection scores, or general sunscreen use. The intervention group showed significantly greater general hat use relative to controls. CONCLUSIONS: The intervention failed to impact most of the outcome measures. Supplementing the behavior-focused intervention package with environmental supports may be warranted.

California↗
PubMedDate not supplied

Estimating the risks of transfusion-associated acquired immune deficiency syndrome and human immunodeficiency virus infection.

The risk of transfusion-associated acquired immunodeficiency syndrome (AIDS) has been difficult to estimate because of the long and variable incubation period. Mathematical modeling suggests there may eventually be 2100 cases among persons aged 13 to 65 who received transfusions between 1978 and 1984. An estimated 12,000 living transfusion recipients of all ages from these years are infected with the human immunodeficiency virus, the virus that causes AIDS. Secondary transmission might be prevented by testing and counseling recipients, but the likelihood of infection in any single recipient is small.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Discrepancies in the reported frequency of cocaine-related deaths, United States, 1983 through 1988.

OBJECTIVE: --To assess the validity of cocaine-related mortality data available from the principal federal sources of information about the frequency of drug abuse deaths in the United States: the national vital statistics system and the Drug Abuse Warning Network (DAWN). DESIGN, SETTING, AND PARTICIPANTS: --We compared the number of cocaine-related deaths reported to national vital statistics and DAWN from 25 metropolitan areas during the years 1983 through 1988. We also compared cocaine-related mortality data reported to national vital statistics with data from all published forensic case series of cocaine-related deaths that occurred during the mid-1980s. RESULTS: --During the 6-year study period, 75% more cocaine-related deaths were reported to DAWN (6057) than to national vital statistics (3466) from the 25 metropolitan areas that were studied. For individual metropolitan areas, the discrepancy between DAWN and vital statistics counts of cocaine-related deaths was as large as a sixfold difference. In six of the seven forensic case series identified in our literature search, the number of cocaine-related deaths exceeded the number of these deaths reported to vital statistics. The largest discrepancy was for cocaine-related deaths in New York, NY, during a 10-month period in 1986 for which 151 deaths were reported in a case series and seven deaths were reported to vital statistics. CONCLUSION: --Improvements in existing public health surveillance systems are needed for (1) full and accurate measurements of the lethal impact of drug abuse epidemics and (2) valid and comprehensive assessments of the effectiveness of national programs designed to prevent drug-related morbidity and mortality.

Cause of Death↗