The contribution of donor quality to differential graft survival in African American and Caucasian renal transplant recipients.

Although a number of factors contributing to the disparity in graft survival between African American (AA) and Caucasian kidney transplant recipients have been described, the role of donor quality is less well understood. This study was undertaken to determine the impact of donor quality differences on this disparity, based on review of UNOS (United Network for Organ Sharing) data on deceased donor renal transplantation from 2000 to 2010. Donor quality was determined by the kidney donor risk index (DRI), and was compared between AA and Caucasian recipients. There were 33,405 Caucasians and 22,577 African Americans in the study, with mean DRI of 1.17 versus 1.27 (p < 0.001), respectively. In analysis 2,446 recipients of each race matched by propensity scoring (based on medical, socioeconomic and immunologic covariates), mean DRI was 1.25 for Caucasians and 1.28 (p = 0.02) for AA. The hazard ratio (HR) for graft failure associated with AA race was 1.8 (p < 0.001) on unadjusted analysis, and decreased to 1.6 (p < 0.001) after matching for DRI. These results indicate a significant disparity in quality of kidneys received by African Americans, which propensity analysis indicates is partially explained by differences in medical, immunologic and socioeconomic factors. Furthermore, this difference in donor quality partially accounts for poorer graft survival in African Americans.

Analysis of BK viral infection after alemtuzumab induction for renal transplant.

UNLABELLED: Induction immunosuppression has provided great advances in reducing the incidence of acute rejection (AR) following kidney transplantation. Despite this success, there has been recent concern over possible increased rates of viral complications when such powerful immunosuppressive therapy is used. This study was undertaken to determine the incidence of BK viral infection following kidney transplantation under alemtuzumab induction therapy. METHODS: With institutional review board approval, a retrospective study was performed of all patients undergoing kidney transplantation under alemtuzumab induction at a single center. The incidence of BK viremia was determined, and univariate analysis was performed to determine factors associated with the development of BK viremia. Further analysis was undertaken, using standard statistical methods, to determine the rates of graft survival and hazard ratio (HR) for AR in patients with and without BK viremia. RESULTS: There were 456 patients in the current study, with a mean age of 51 years. The majority of these (61.8%) were male, and 73.5% were Caucasian. The overall incidence of BK viremia identified on routine screening was 6.6%. Univariate analysis failed to identify any significant predictors of BK viremia. One-, 3-, and 5-year graft survival for patients who developed BK viremia was 96.6%, 91.7%, and 91.7%, respectively, compared with 94.1%, 87.8%, and 80.2% for patients without BK viremia (P = 0.860). BK viremia was associated with a significantly increased risk for AR (HR 3.48, 95% confidence interval 1.24-9.76; P = 0.018). CONCLUSION: The incidence of BK viremia following alemtuzumab induction appears to be in concordance with the published literature, with satisfactory graft survival rates. BK viremia is, however, associated with an increased risk for AR.

A literature-based cost analysis of tissue plasminogen activator for prevention of biliary stricture in donation after circulatory death liver transplantation.

INTRODUCTION: This study sought to approximate the cost-effectiveness of tPA utilization for prevention of biliary strictures (PTBS) in donation after circulatory death liver transplantation (DCD-LT). METHODS: Previously-reported PTBS rates in DCD-LT with and without tPA were used to calculate the number needed to treat (NNT) for prevention of one PTBS. The incremental cost of PTBS was then used to determine the cost effectiveness of tPA for prevention of PTBS. RESULTS: The incidence of PTBS in the setting of tPA administration was 20%, while incidence in patients without tPA use was 43% (p < 0.001). Meta-analysis demonstrated a risk reduction of 15.7%, which translated into a NNT of 6.4. Cost associated with treating 6.4 patients was $50,353. Based on an incremental cost of $81,888 associated with PTBS management, use of tPA in DCD-LT protocols was estimated to save $31,528 per PTBS prevented. CONCLUSION: Utilization of tPA in DCD-LT protocols represents one possible cost-effective strategy for prevention of PTBS in DCD-LT.

A model (BSurvE) for estimating the prevalence of bovine spongiform encephalopathy in a national herd.

We developed the BSurvE spreadsheet model to estimate the true prevalence of bovine spongiform encephalopathy (BSE) in a national cattle population, and evaluate national BSE surveillance programs. BSurvE uses BSE surveillance data and demographic information about the national cattle population. The proportion of each cohort infected with BSE is found by equating the observed number of infected animals with the number expected, following a series of probability calculations and assuming a binomial distribution for the number of infected animals detected in each surveillance stream. BSurvE has been used in a series of international workshops, where analysis of national datasets demonstrated patterns of cohort infection that were consistent with infection-control activities within the country. The results also reflected the timing of known events that were high-risk for introduction of the infectious agent.

A model (BSurvE) for evaluating national surveillance programs for bovine spongiform encephalopathy.

Our BSurvE spreadsheet model estimates the BSE prevalence in a national cattle population, and can be used to evaluate and compare alternative strategies for a national surveillance program. Each individual surveillance test has a point value (based on demographic and epidemiological information) that reflects the likelihood of detecting BSE in an animal of a given age leaving the population via the stated surveillance stream. A target sum point value for the country is calculated according to a user-defined design prevalence and confidence level, the number of cases detected in animals born after the selected starting date and the national adult-herd size. Surveillance tests carried out on different sub-populations of animals are ranked according to the number of points gained per unit cost, and the results can be used in designing alternative surveillance programs.

Determining the sensitivity of abattoir surveillance for ovine Johne's disease.

OBJECTIVE: The objective of this study was to determine the sensitivity of abattoir surveillance of intestinal tract lesions for detecting ovine Johne's disease (OJD) under normal meatwork conditions. DESIGN: The design of this study was a diagnostic test validation. The three OJD inspectors were the diagnostic test and follow-up histopathological examination was used for test validation. PROCEDURE: Approximately 1200 sheep were procured from known high prevalence OJD infected farms. The sheep viscera were tagged (numbered) and then examined as they were processed on the abattoir line by three experienced meat inspectors. Their observations were independently recorded on a cassette tape. Specified sections of viscera were prepared and subjected to histopathological examination and these results were compared with the inspector diagnoses. RESULTS: The sensitivity of abattoir inspection for OJD varied between inspectors from 53 percent to 87 percent. The specificity varied from 97 to 100 percent. It appeared that the level of sensitivity for detecting disease was higher in lines of sheep where the disease was more prevalent. It also appeared that formal training was an important aspect in ensuring a high level CONCLUSION: Abattoir surveillance is a very economical and rapid method of assessing the OJD status of sheep. On the basis of these results it is reasonable to suggest that abattoir surveillance has a sensitivity of approximately 70 percent. This technique is useful as an ancillary to other testing regimes for negative assurance programs where a sheep identification system is used.

Increased peritoneal fluid lactic acid values and progressive bowel strangulation in dogs.

In the present study, we determined values for peritoneal fluid and blood ammonia, amylase, and lactic acid content in 11 dogs after experimental bowel strangulation. In the nine survivors of this group, we demonstrated a near linear increase in peritoneal fluid lactic acid over a 24-hour period, during which the plasma lactic acid remained relatively constant. A significant increase in peritoneal fluid ammonia was also demonstrated, but this did not occur until more than 16 hours after strangulation. In a second group of two dogs in which simple obstruction was produced, no significant increase in peritoneal fluid lactic acid or ammonia occurred. We did not find significant changes in peritoneal fluid amylase in this study. These data suggest that the determination of peritoneal fluid lactic acid content, especially when compared with concomitant plasma lactic acid, may be useful in the accurate preoperative diagnosis of bowel strangulation.

A review of Q fever in Australia 1991-1994.

Q fever continues to be an important disease in Australia. Despite the development of an effective vaccine that has been commercially available since 1989, the number of cases notified has continued to increase. This study reviewed national notifications of Q fever between 1991 and 1994, together with demographic, socioeconomic and occupational information, to investigate temporal and spatial disease patterns. Based on notification data, Q fever can be considered primarily a disease of adult males that occurs in eastern Australia: southern Queensland and northern New South Wales have the highest levels of activity. A significant association between Q fever activity of areas and the presence of livestock was found. A strong association with the meat industry was also confirmed. Q fever is conservatively estimated to cost Australia around A$1 million and more than 1700 weeks of work time annually. There is a need to increase awareness of this disease and its prevention. An extension program in rural communities and provision of vaccine to all abattoir workers would appear to be sensible public health approaches.

Sense and sensitivity--designing surveys based on an imperfect test.

Designing a survey to detect the presence of a disease is complicated if the test used to detect the disease has non-perfect sensitivity and specificity. This paper gives two new approximations that simplify such a task. The first gives the cumulative probability distribution of the number of apparently diseased animals detected in the survey and the second gives the probability that no diseased animals are detected if the test used has 100% specificity. Both approximations can be used to determine confidence limits for the true prevalence. The main purpose of the approximations is to determine the number of animals that need to be tested to be confident that a herd is free of disease, and then to determine the number of herds that need to be tested to demonstrate area freedom. One approach to such an area survey has been to classify each herd as diseased or not based on the number of reactors found in the herd, and then to use the number of herds classified as diseased to determine the area's status. The paper points out that basing the decision simply on the magnitude of the maximum observed within-herd reactor proportion results in a more accurate survey for the same number of animals and herds tested.

Demonstrating disease freedom-combining confidence levels.

Part of the requirements for demonstrating disease freedom usually will be that sufficient testing be done to give a specified confidence of detecting the disease if it were present at a specified level. Often, this requirement is translated into a fixed testing regime that must be followed (an inflexible approach that might not be the most economic or practical solution).A more flexible approach is to specify the capabilities of the various tests that can be used to detect the disease, and let the party hoping to demonstrate disease freedom decide upon the testing regime. The question then arises as to how to combine information that can come from a variety of sources over a period of time to give an overall level of confidence. Two methods are given. The first, an exact method based on multiplying probabilities, would be more appropriate for a survey of an area in which no disease is thought to be present. The second method (more appropriate for a herd-assurance program within an infected area) is a point-based system that takes into account the different sensitivities of the methods used to detect disease and the change in prevalence over time. It allocates points for each test done proportional to the sensitivity of the test and the prevalence at the time of testing.

A national serological survey to verify Australia's freedom from porcine reproductive and respiratory syndrome.

OBJECTIVE: To provide serological data to support Australia's claim of freedom from porcine reproductive and respiratory syndrome. DESIGN: A national serological survey was designed to provide 99% confidence of detecting at least one infected pig herd in Australia, assuming that at least 5% of herds would have been exposed to porcine reproductive and respiratory syndrome virus and that at least 25% of the 'finisher' pigs in these herds would have antibodies to the virus. PROCEDURE: A two-stage testing regime was used. All samples were tested with a commercially available enzyme-linked immunosorbent assay. If assay reactions were found, all samples from the herd were to be tested using the indirect immunofluorescence antibody assay. RESULTS: Of the 875 samples from 163 herds from all States in Australia, there was some evidence of reactivity in only four samples from four herds on the enzyme-linked immunosorbent assay. Further testing using the indirect immunofluorescence antibody assay according to the study protocol demonstrated that the reactions were not due to the presence of specific porcine reproductive and respiratory syndrome virus antibodies in the sera. CONCLUSION: The results of this study support the view that Australian pigs are free of porcine reproductive and respiratory syndrome virus.

A health program for commercial dairy herds. 1. Objectives and methods.

A health program for dairy herds is defined as a planned and coordinated approach to achieving and maintaining optimal health and productive efficiency of livestock. A program is described, which has been developed over a period of eight years to fulfill this definition in providing veterinary services to commercial dairy herds. It is demonstrated that clinical veterinary services to participating herds did not satisfactorily achieve the stated aim and therefore an alternative approach was developed. This approach is centred around the concept of performance targets, and each herd is monitored closely by means of a computer-based health and productivity monitoring system in order to detect deviation from target performance. When such deviations occur, the monitoring system is used to diagnose the nature of the problem. The detailed targets adopted in this study are described and the examinations which are undertaken on cattle are outlined. These examinations are aimed at correcting problems, or at confirming satisfactory performance. Further details of the findings of the study are outlined in following papers.

A health program for commercial dairy herds. 2. Data processing.

The development of a computerised data handling and analysis system to aid the operation of a health and management program for commercial dairy herds is described. The aims for the system are outlined, and the development of the system over a period of 8 years to meet these aims is described. The documentation used in the current system is described in relation to the various procedures involved in the operation of the dairy herd health program. Two features which make this system unique are its use for the selection of problem and high risk cows for examination and treatment, and the provision of analyses of recent performance in a number of facets of health and production, which aid in the identification of emerging problems. It is considered that future improvements in the system will be in the areas of milk production recording and calf rearing and disease recording.

A health program for commercial dairy herds. 3. Changes in reproductive performance.

A health program service was implemented on 9 farms, for periods ranging up to 7 years. Reproductive performance was substantially improved, when performance indicators were compared with values for the herds prior to commencement of the service. On average, the mean calving to conception intervals for the herds were reduced by 24 days over their periods of participation in the program, from an initial value of 119 days. The intercalving interval was reduced by an average of 27 days. This improvement was associated with a reduction in the mean dry period length of 20 days, from an initial value of 117 days. There was a tendency for the lactation lengths to be reduced to an undesirable extent due to slow adaptation by management to the improvement in reproductive performance, but the problem was corrected late in the study. The improvement in performance was attributed to improved oestrus detection, correction of temporary nutritional deficiencies, and prompt treatment of genital tract disorders in individual animals. Results for a range of performance indicators related to reproductive function are reported in detail.

A health program for commercial dairy herds. 4. Changes in mastitis prevalence.

A study of mastitis prevalence in 10 herds which participated in a herd health program is reported for varying periods, up to a maximum of 10 years. The program was based on teat dipping with idophor or sodium hypochlorite teat dip, regular maintenance of the milking machine, and selective dry period treatment of quarters which were classified as infected on the basis of California Mastitis Test score and bacteriological examination of milk samples taken before drying off. The procedures reduced mastitis prevalence (measured in cows being dried off), incidence of clinical mastitis, and disposal of cows due to mastitis. Results obtained were similar to those found in short-term studies of control programs based on teat dipping and dry period therapy. The only significant difficulty which arose in maintaining the control program over 10 years was loss of enthusiasm by farmers for teat dipping. This was usually induced by teat irritation problems apparently caused by teat dipping. The use of a monitoring procedure for mastitis prevalence was important in persuading farmers to return to the use of teat dip.

A health program for commercial dairy herds. 5. The occurrence of specific disease entities.

Disease incidence data was collected from 9 dairy herds which participated in a herd health program. A total of 11,534 cow years was analysed. In common with other Australian data, the important clinical diseases were mastitis and infertility. There was an average level of 43.4 disease incidents per year per 100 animals at risk. An average of 18.6% of the herd left each year. This comprised 1.5% through death and 17.1% through sale. Disease accounted for the disposal of 9.8% of animals, and management reasons for 8.8%. These findings are similar to those of other studies in Australia and in other countries, but the results in this study were based on a longer period and on closer surveillance.

Inspecting and monitoring on a restricted budget--where best to look?

Generally, only limited resources are available for quarantine inspection, compliance verification and disease surveillance. How best to allocate a fixed amount of resources depends on how we define 'best'. This paper considers a number of definitions that cover a range of likely operational activities and derives sampling and testing strategies that take advantage of any variation in risk within the population of interest to increase their efficiency.