The estimation of prevalence for the evaluation of a screening program

The evaluation of a screening program in which only screen positives are tested with more definitive diagnostic procedures requires the estimation of prevalence so that the number of screen negatives who are actually diseased can also be estimated. Methodology for incorporating an assessment of the variability of the prevalence rate between as well as within subpopulations is presented and illustrated. The procedure described leads to a negative binomial probability distribution on the number of diseased individuals who were missed by the combined screening-diagnostic protocol.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24292/1/0000558.pd

Urine Orotic Acid-Orotidine Levels in Azaribine-Treated Patients with Psoriasis

Azaribine, as a pyrimidine analog, blocks the decarboxylase conversion of orotidylic acid to uridine monophosphate with a resultant excretion of accumulated orotic acid and orotidine in the urine. Patients treated with azaribine may develop transitory, severe central nervous system symptoms of depression, lethargy, and ataxia. These side effects are not predictable from oral dosage, and blood levels of the drug are very difficult to determine. All of our psoriatic patients treated with azaribine excreted large but variable amounts of orotic acid-orotidine in the urine. Spot urine ratios of orotic acid-orotidine:creatinine correlated very well with measured 24-hr urine output of orotic acid-orotidine. Patients with central nervous system symptoms were found to have very high urine levels of orotic acid orotidine. These symptoms can be prevented by monitoring the urinary orotic acid-orotidine:creatinine ratio levels and keeping them within a range which is still compatible with successful management of the psoriatic lesions

Sequence length for repeated screening tests

The cost of detecting asymptomatic colonic cancer with a sequence of occult blood tests by the guaiac method is investigated to determine the effect of sequence length. The results are sensitive to the definition of a screen positive and a variety of definitions of a positive screen are investigated. It is found that additional tests, when practical, can be used effectively to reduce the average cost of detection per case and to decrease markedly the probability of a false positive screen without sacrificing high sensitivity even when the prevalence of disease is low. The results hold for a variety of combinations of test and prevalence parameters. This strengthens the conclusion and makes the results more generally applicable.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22753/1/0000308.pd

Exponential decontamination models for count data

Several models are developed for the estimation of the rate of exponential die-off from decontamination data. Calculations with illustrative data are reported which indicate that the estimation of this rate and its variance are sensitive to changes in modelling assumptions. Since extrapolation using this estimated rate is used in the specification of planetary quarantine standards, special care should be taken in the selection of an appropriate model and corresponding estimation procedure for the analysis of each set of decontamination data to be used for this purpose.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43352/1/11084_2004_Article_BF00924214.pd

Predicting the long-term impact of antiretroviral therapy scale-up on population incidence of tuberculosis.

OBJECTIVE: To investigate the impact of antiretroviral therapy (ART) on long-term population-level tuberculosis disease (TB) incidence in sub-Saharan Africa. METHODS: We used a mathematical model to consider the effect of different assumptions about life expectancy and TB risk during long-term ART under alternative scenarios for trends in population HIV incidence and ART coverage. RESULTS: All the scenarios we explored predicted that the widespread introduction of ART would initially reduce population-level TB incidence. However, many modelled scenarios projected a rebound in population-level TB incidence after around 20 years. This rebound was predicted to exceed the TB incidence present before ART scale-up if decreases in HIV incidence during the same period were not sufficiently rapid or if the protective effect of ART on TB was not sustained. Nevertheless, most scenarios predicted a reduction in the cumulative TB incidence when accompanied by a relative decline in HIV incidence of more than 10% each year. CONCLUSIONS: Despite short-term benefits of ART scale-up on population TB incidence in sub-Saharan Africa, longer-term projections raise the possibility of a rebound in TB incidence. This highlights the importance of sustaining good adherence and immunologic response to ART and, crucially, the need for effective HIV preventive interventions, including early widespread implementation of ART

Interpreting behavioral, biomedical, and psychological relationships in chronic disease from 2 x 2 tables using correlation,

Correlations of 0.3 and 0.4 in psychological studies in chronic illness (e.g. diabetes) have been criticized as having little clinical importance. The present article suggests that correlation coefficients be interpreted as binomial effect size displays (BESD) as a means of gleaning the clinical importance of a given correlation coefficient. The BESD is easily understood, computed, and applied to research in chronic disease. An illustration is provided in which a r of 0.2 is shown to correspond to a BESD in which the success rate is improved from 40 to 60%. Using BESD to interpret the meaningfulness of relationships, correlations as low as 0.2 may have clinical importance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26429/1/0000517.pd

The Cold Peace: Russo-Western Relations as a Mimetic Cold War

In 1989–1991 the geo-ideological contestation between two blocs was swept away, together with the ideology of civil war and its concomitant Cold War played out on the larger stage. Paradoxically, while the domestic sources of Cold War confrontation have been transcended, its external manifestations remain in the form of a ‘legacy’ geopolitical contest between the dominant hegemonic power (the United States) and a number of potential rising great powers, of which Russia is one. The post-revolutionary era is thus one of a ‘cold peace’. A cold peace is a mimetic cold war. In other words, while a cold war accepts the logic of conflict in the international system and between certain protagonists in particular, a cold peace reproduces the behavioural patterns of a cold war but suppresses acceptance of the logic of behaviour. A cold peace is accompanied by a singular stress on notions of victimhood for some and undigested and bitter victory for others. The perceived victim status of one set of actors provides the seedbed for renewed conflict, while the ‘victory’ of the others cannot be consolidated in some sort of relatively unchallenged post-conflict order. The ‘universalism’ of the victors is now challenged by Russia's neo-revisionist policy, including not so much the defence of Westphalian notions of sovereignty but the espousal of an international system with room for multiple systems (the Schmittean pluriverse)

Atomic Resonance and Scattering

Contains reports on six research projects.National Science Foundation (Grant PHY 83-06273)U.S. Navy - Office of Naval Research (Contract N00014-79-C-0183)Joint Services Electronics Program (Contract DAALO03-86-K-0002)National Science Foundation (Grant PHY 84-11483)National Science Foundation (Grant PHY 86-05893)National Science Foundation (Grant ECS 84-21392)U.S. Navy - Office of Naval Research (Contract N00014-83-K-0695)National Science Foundation (Grant CHE 84-21392

Outcome of primary resurfacing hip replacement: evaluation of risk factors for early revision: 12,093 replacements from the Australian Joint Registry

BACKGROUND AND PURPOSE: The outcome of modern resurfacing remains to be determined. The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) started collection of data on hip resurfacing at a time when modern resurfacing was started in Australia. The rate of resurfacing has been higher in Australia than in many other countries. As a result, the AOANJRR has one of the largest series of resurfacing procedures. This study was undertaken to determine the results of this series and the risk factors associated with revision. PATIENTS AND METHODS: Data from the AOANJRR were used to analyze the survivorship of 12,093 primary resurfacing hip replacements reported to the Joint Replacement Registry between September 1999 and December 2008. This was compared to the results of primary conventional total hip replacement reported during the same period. The Kaplan-Meier method and proportional hazards models were used to determine risk factors such as age, sex, femoral component size, primary diagnosis, and implant design. RESULTS: Female patients had a higher revision rate than males; however, after adjusting for head size, the revision rates were similar. Prostheses with head sizes of less than 50 mm had a higher revision rate than those with head sizes of 50 mm or more. At 8 years, the cumulative per cent revision of hip resurfacing was 5.3 (4.6-6.2), as compared to 4.0 (3.8-4.2) for total hip replacement. However, in osteoarthritis patients aged less than 55 years with head sizes of 50 mm or more, the 7-year cumulative per cent revision for hip resurfacing was 3.0 (2.2-4.2). Also, hips with dysplasia and some implant designs had an increased risk of revision. INTERPRETATION: Risk factors for revision of resurfacing were older patients, smaller femoral head size, patients with developmental dysplasia, and certain implant designs. These results highlight the importance of patient and prosthesis selection in optimizing the outcome of hip resurfacing