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Biomedical subjects

J D Hamilton

Publications and source records attributed to J D Hamilton.

At least 55 records · Page 3Linked to original sources
PubMed1994

The accuracy of self-report of herpes zoster.

The accuracy of self-report of herpes zoster was investigated in the Duke Established Populations for Epidemiological Studies of the Elderly, a longitudinal study of 4162 community-dwelling elderly persons residing in North Carolina, 1986-1993. The authors compared self-reports of zoster with physician diagnosis of zoster and with a zoster verification questionnaire (ZVQ). Compared to physician diagnosis, 3.2% (95% confidence interval 0-61%) of self-reports of zoster (n = 31) were false-positive and no denials of zoster (n = 63) were false-negative. The agreement of self-reports to physician diagnosis was 98.9%, the sensitivity and negative predictive value were 100%, the specificity was 98.4% and the positive predictive value was 96.7%. The ZVQ comparisons were similarly high. These data suggest that the frequency of false-positive and false-negative reports of zoster is low in this elderly population. Zoster self-reports appear to be accurate and suitable for epidemiological investigations.

Aged↗
PubMed1994

Delayed-type hypersensitivity skin tests are an independent predictor of human immunodeficiency virus disease progression. Department of Veterans Affairs Cooperative Study Group.

Delayed-type hypersensitivity (DTH) testing was evaluated as a predictor of human immunodeficiency virus (HIV) disease progression in 336 symptomatic patients with baseline CD4 cell counts of 200-500/mm3 who were participating in a randomized trial of early versus late therapy with zidovudine. Patients with a response of > 2 mm to any of seven antigens were categorized as reactive; those without were anergic. Anergic patients were significantly more likely than reactive patients to have HIV disease progression as evidenced by decrease in CD4 cell count (52% vs. 27%), development of AIDS (33% vs. 17%), or death (18% vs. 9%) (P < or = .02), irrespective of time of zidovudine initiation. By multivariate analysis, DTH results were an independent predictor of HIV progression separate from CD4 cell count, p24 antigen positivity, or level of beta 2-microglobulin. DTH skin tests are an independent predictor of HIV disease progression and may be of value in the evaluation of a patient's immune status.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Cost effectiveness analysis of early zidovudine treatment of HIV infected patients.

OBJECTIVE--To compare cost effectiveness of early and later treatment with zidovudine for patients infected with HIV. DESIGN--Markov chain analysis of cost effectiveness based on results of use of health care and efficacy from a trial of zidovudine treatment. SETTING--Seven Veterans Affairs medical centres in the United States. SUBJECTS--338 patients with symptomatic HIV infection and a lymphocyte count of 200 x 10(6) to 500 x 10(6) CD4 cells/l. INTERVENTIONS--Zidovudine 1500 mg/day started either at recruitment to the trial or when CD4 cell count fell below 200 x 10(6)/l. MAIN OUTCOME MEASURES--Health care costs and rates of disease progression between six clinical states of HIV infection. RESULTS--Patients given early treatment with zidovudine remained without AIDS for an extra two months at a cost of $10,750 for each extra month without AIDS (at 1991 costs). Cost effectiveness ratio was most sensitive to the cost of zidovudine and to the quality of life of patients receiving early treatment. At treatment of 500 mg/day the cost effectiveness ratio for early treatment was $5432 for each extra month without AIDS. Patients given early treatment experienced more side effects, and if their quality of life was devalued by 8% compared with patients treated later the two treatments were equivalent in terms of quality adjusted months of life without AIDS. CONCLUSIONS--Early treatment with zidovudine is expensive and is very sensitive to the cost of zidovudine and to potential reductions in quality of life of patients who experience side effects. Doctors should reconsider early treatment with zidovudine for patients who experience side effects that substantially compromise their quality of life.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Ethical dilemmas in continuing a zidovudine trial after early termination of similar trials.

Ethical dilemmas caused by external events and an interim subset analysis raised concerns about continuing a long-term VA clinical trial comparing early with later zidovudine therapy for symptomatic human immunodeficiency virus (HIV) infection. The first external event was the early termination of other, apparently similar, trials conducted by the AIDS Clinical Trials Group (ACTG) and the announced clear benefits for the zidovudine-treated patients. Interim analysis of the VA trial at this time did not show similar benefits. Subset analyses were performed to explore factors that might explain the different results. These suggested a difference in response to zidovudine in white and minority groups. The Data Monitoring Board and a special advisory panel reviewed these data and concluded that, since the VA results were neutral overall and the subset analyses based on small numbers, the trial should continue. By conference call, the study cochairmen and biostatistician discussed this decision with study personnel without revealing interim results, and study personnel passed the information on to patients at the participating centers. The second event was in March 1990, when the Food and Drug Administration (FDA) approved earlier use of zidovudine, which applied to patients still in the VA trial. Patients were asked to reaffirm their participation by signing a new informed consent that explained the findings reported by the ACTG, the FDA-approved revised recommendations, and the rationale for continuation of the VA trial. The consent form emphasized that continued masked therapy was optional and that unmasked treatment and follow-up would be provided to patients requesting it. Seventy-four percent of the participants chose to continue masked therapy. We conclude that when new external data are announced, informed participation in a long-term clinical trial may require a revised consent form and that it is ethical and practical to present this without disclosure of interim study results.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Hepatitis B vaccination and booster in predialysis patients: a 4-year analysis.

Patients undergoing chronic haemodialysis are at increased risk for infection with hepatitis B virus (HBV), but response to currently available vaccines is suboptimal. We undertook a 4-year prospective study of the efficacy of hepatitis B vaccine in patients with renal insufficiency, who were not yet dialysis-dependent. A booster dose of Recombivax HB was given at 3 or 4 years to those whose antibody levels fell below a predetermined point. Progression to dialysis was associated with poorer initial response to vaccination compared with those remaining dialysis-independent, but response to booster immunization was favourable in both groups. It is concluded that immunization of predialysis patients and subsequent booster vaccine results in a more favourable antibody response than has been seen historically in haemodialysis patients. Local endemicity and cost of vaccine should be considered when determining the best strategy for HBV immunization of patients with chronic renal failure.

Cohort Studies↗
PubMed1993

Association between genetic variation at the porphobilinogen deaminase gene and schizophrenia.

There is growing evidence that some genetic predisposition is important in the etiology of schizophrenia. We have sought to implicate a major gene by performing a candidate gene association study comparing the allele frequencies of seven restriction fragment length polymorphisms (RFLPs) at six loci in both a psychiatrically normal control group (N = 51) and an affected (schizophrenia or schizoaffective disorder) group (N = 55). Each group comprised Caucasians of northern European origin. The candidate areas (D5S39, D5S78, dopamine receptor D2 (DRD2), D11S29, porphobilinogen deaminase (PBGD), and D11S84) were selected on the basis of prior cytogenetic findings in schizophrenics, linkage studies, and/or implicated gene products. The presence of a polymorphic ApaLI site within the PBGD gene showed a significant association with the presence of illness (P = 0.02). The relative risk of possessing the allele with the ApaLI site was 2.10. No significant association was found with any of the six other RFLPs. Our data suggests that either the PBGD gene itself or an unknown gene linked to and/or in linkage disequilibrium with the PBGD locus predisposes some individuals to schizophrenia. Independent replication of these findings will be required to determine their relevance to schizophrenia.

Adolescent↗
PubMed1993

Detection of murine cytomegalovirus immediate early 1 transcripts in the spleens of latently infected mice.

The spleens of mice latently infected with murine cytomegalovirus were examined by reverse transcription followed by the polymerase chain reaction to assay for transcriptional activity of the viral immediate early 1 gene. Transcripts were detected in 6 of 8 animals at a level between 50 and 500 copies in 200 ng of total cellular RNA. This level appears to be roughly 10-fold higher than that of viral genome even though viral DNA is more readily detectable. These data suggest that a significant fraction of latent murine cytomegalovirus is transcriptionally active in the spleen, which may be indicative of an abortive infection or possibly low-level persistence or a transient reactivation.

Amino Acid Sequence↗
PubMed1993

Quality assessment and improvement in group psychotherapy.

OBJECTIVE: The authors sought a practical means of monitoring and evaluating group psychotherapy, using existing clinical resources, for purposes of quality improvement and education on a large general hospital psychiatric service. METHOD: Monitoring indicators were developed which addressed 1) the integration of group psychotherapy into treatment planning and 2) the competence and technique of group psychotherapists. The second indicator was assessed by skilled observers using a newly constructed Group Psychotherapy Rating Scale in direct observation of group psychotherapy sessions. The rating scale was examined for interrater reliability and, as a measure of construct validity, for its ability to distinguish the performance of professional staff therapists from that of trainees. RESULTS: The indicators provided useful monitors of the use and quality of group psychotherapy. The rating scale had satisfactory interrater reliability and construct validity. The immediate constructive educational critique given by the observers of the therapy groups was highly valued by group therapists. CONCLUSIONS: The monitoring and evaluation program proved to be a practical, positive, and inexpensive means of assuring and improving the quality of group psychotherapy in a clinical setting.

Humans↗
PubMed1993

Evaluation of a saliva alcohol test stick as a therapeutic adjunct in an alcoholism treatment program.

This study was designed to evaluate the clinical usefulness of a saliva alcohol dipstick by comparing dipstick saliva alcohol concentrations to simultaneous blood and urine alcohol concentrations. The sample consisted of 211 saliva tests and blood alcohol concentrations and 189 urine alcohol concentrations. The dipsticks had a specificity of 0.965, a sensitivity of 0.895, a positive predictive value of 0.850, a negative predictive value of 0.977 and a Pearson's product moment correlation coefficient of 0.609 for blood alcohol concentrations and salivary alcohol concentrations, suggesting that the saliva dipstick is useful as a qualitative test in certain settings but is less useful than previously reported as a semiquantitative test.

Adult↗
PubMed1993

Zidovudine resistance, syncytium-inducing phenotype, and HIV disease progression in a case-control study. The VA Cooperative Study Group.

A case-control study of patients with progressive (cases) or nonprogressive (controls) disease was designed to determine the association among disease progression, zidovudine sensitivity, and syncytium-inducing phenotype. Viral isolates were screened for sensitivity to zidovudine using a peripheral blood mononuclear cell-based assay and for syncytium-inducing (SI) phenotype in MT2 cell culture. Thirty-four patients, whose disease progressed to AIDS or whose CD4 cell numbers fell < 200 cells/mm3, were matched with 34 patients whose conditions had not progressed or whose CD4 cell numbers remained > 200 cells/mm3. Virus was successfully cultured from both the progressor and the nonprogressor in 17 of these 34 matched case-control pairs. In six of the 17 pairs, virus isolated from the progressor had an IC50 (50% inhibitory concentration) for zidovudine > 1 microM and at least threefold greater than the IC50 of virus isolated from the matched nonprogressor (p = 0.04). In 16 of these 17 pairs the virus isolated from the progressor had the SI phenotype, indicative of high cytopathogenicity, while the virus from the matched nonprogressor had a non-syncytium-inducing phenotype (p < 0.0001). Zidovudine therapy did not appear to select for the SI phenotype in this patient population. A statistically significant association between high-level zidovudine resistance and clinical disease progression was demonstrated. A statistically significant association between the SI phenotype and disease progression was demonstrated. The results suggest that disease progression while being treated with zidovudine therapy may be more closely associated with the SI phenotype than with zidovudine resistance.

Acquired Immunodeficiency Syndrome↗
PubMed1993

A cost-effectiveness analysis of hepatitis B vaccine in predialysis patients.

OBJECTIVE: Our objective was to assess the cost effectiveness of hepatitis B vaccine in predialysis patients. DATA SOURCES: Costs were calculated from estimated rates of health services use and unit costs of resource use. Efficacy data were based on probability estimates from the medical literature and included vaccination response rates, anticipated hepatitis B virus (HBV) infection rates, and outcomes from HBV. STUDY DESIGN: Costs and effectiveness of HBV vaccination was modeled with a decision tree constructed to analyze three vaccination strategies for patients with renal insufficiency: vaccine given prior to dialysis, vaccine given at time of dialysis, and no vaccine. Sensitivity analyses were performed to assess the effect of varying important clinical and cost variables. DATA COLLECTION/EXTRACTION METHODS: All analyses were based on efficacy and cost estimates derived from the medical literature. Analyses were conducted with the aid of SMLTREE software. PRINCIPAL FINDINGS: The number of patients requiring vaccination per case of HBV prevented was higher for dialysis patients (625 vaccinees/case prevented) than for predialysis patients (434 vaccinees/case prevented). The cost-effectiveness ratios were $25,313/case of HBV prevented for vaccination at the time of dialysis and $31,111 for the predialysis vaccine. When a higher HBV infection rate (based on clinical trial data) was substituted in the analysis, the cost effectiveness of a predialysis vaccination strategy improved to $856 per case prevented. Results were sensitive to the cost of the vaccine and the incidence of HBV infection in dialysis patients. For the predialysis strategy to become cost saving, the price of the vaccine would have to decrease from $114 to $1.50, or the incidence of infection would have to increase from 0.6 percent to 38 percent, holding all other variables constant. CONCLUSIONS: Additional HBV infection can be prevented by immunizing predialysis patients, but the cost is high. Decisions concerning vaccination policy should be influenced by local prevalence of HBV infection.

Cost of Illness↗
PubMed1992

A controlled trial of early versus late treatment with zidovudine in symptomatic human immunodeficiency virus infection. Results of the Veterans Affairs Cooperative Study.

BACKGROUND: Zidovudine is recommended for asymptomatic and early symptomatic human immunodeficiency virus (HIV) infection. The best time to initiate zidovudine treatment remains uncertain, however, and whether early treatment improves survival has not been established. METHODS: We conducted a multicenter, randomized, double-blind trial that compared early zidovudine therapy (beginning at 1500 mg per day) with late therapy in HIV-infected patients who were symptomatic and had CD4+ counts between 0.2 x 10(9) and 0.5 x 10(9) cells per liter (200 to 500 per cubic millimeter) at entry. Those assigned to late therapy initially received placebo and began zidovudine when their CD4+ counts fell below 0.2 x 10(9) per liter (200 per cubic millimeter) or when the acquired immunodeficiency syndrome (AIDS) developed. RESULTS: During a mean follow-up period of more than two years, there were 23 deaths in the early-therapy group (n = 170) and 20 deaths in the late-therapy group (n = 168) (P = 0.48; relative risk [late vs. early], 0.81; 95 percent confidence interval, 0.44 to 1.59). In the early-therapy group, 28 patients progressed to AIDS, as compared with 48 in the late-therapy group (P = 0.02; relative risk, 1.76; 95 percent confidence interval, 1.1 to 2.8). Early therapy increased the time until CD4+ counts fell below 0.2 x 10(9) per liter (200 per cubic millimeter), and it produced more conversions from positive to negative for serum p24 antigen. Early therapy was associated with more anemia, leukopenia, nausea, vomiting, and diarrhea, whereas late therapy was associated with more skin rash. CONCLUSIONS: In symptomatic patients with HIV infection, early treatment with zidovudine delays progression to AIDS, but in this controlled study it did not improve survival, and it was associated with more side effects.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Aging and reactivation of latent murine cytomegalovirus.

BALB/c mice were experimentally infected with murine cytomegalovirus (MCMV) to discover whether latent MCMV persisted in aging mice and to examine the effect of aging on MCMV reactivation. Latently infected mice received saline, cyclophosphamide, or allogeneic blood at 6 and 18 months of age. MCMV DNA was detected by polymerase chain reaction in submaxillary salivary gland biopsy specimens from saline-treated young and old mice. Evidence of MCMV reactivation was sought by culture of biopsy specimens and by MCMV IgG ELISA of pre- and posttreatment sera from all animals. Very few cyclophosphamide- or saline-treated mice reactivated MCMV at either age, but young transfused mice reactivated MCMV significantly more often than did old transfused mice. These experiments indicate that MCMV DNA persists in the salivary gland of aging mice but that the likelihood of MCMV reactivation does not increase with age.

Aging↗