Nokuthaba Sibanda

Pregnancy after organ transplantation: a report from the UK Transplant pregnancy registry.

Background. Maternal and fetal complications in pregnancies after renal transplantation have been highlighted in several reports, but information on their main predisposing factors is limited. The U.K. Transplant Pregnancy Registry was established in 1997 to obtain detailed information on pregnancies in female organ transplant recipients across the U.K. Methods. For each female kidney, liver, or cardiothoracic organ transplant recipient who had had a recent pregnancy, data on maternal and fetal factors and pregnancy outcomes were collected using forms completed by their transplant follow-up and obstetric units. For kidney transplant recipients, the factors that influence pregnancy outcome were studied using logistic regression, and the effect of pregnancy on graft function was analyzed. Results. There were live births in 83%, 69%, and 79% of pregnancies in cardiothoracic organ, liver, and kidney recipients, respectively. In 50% of live births from renal patients, delivery was preterm (<37 weeks), with 83% of the preterm infants delivered via caesarean. Preterm delivery was associated with maternal drug-treated hypertension and impaired renal function. A matched case–control study showed no evidence of increased renal allograft loss after pregnancy. A univariate survival analysis, however, suggested an association between drug-treated hypertension during pregnancy and poorer postpregnancy graft survival. In patients with prepregnancy serum creatinine (SCr) >150 &mgr;mol/L, a trend toward increased postpregnancy SCr was identified. Conclusions. Pregnancy is likely to end in a live birth in a majority of organ transplant recipients. In patients with greater prepregnancy SCr and/or drug-treated hypertension during pregnancy, however, subsequent renal function may be adversely affected.

Mortality in men admitted to hospital with acute urinary retention: database analysis

Objectives To investigate mortality in men admitted to hospital with acute urinary retention and to report on the effects of comorbidity on mortality. Design Analysis of the hospital episode statistics database linked to the mortality database of the Office for National Statistics. Setting NHS hospital trusts in England, 1998-2005. Participants All men aged over 45 who were admitted to NHS hospitals in England with a first episode of acute urinary retention. Main outcome measures Mortality in the first year after acute urinary retention and standardised mortality ratio against the general population. Results During the study period, 176 046 men aged over 45 were admitted to hospital with a first episode of acute urinary retention. In 100 067 men with spontaneous acute urinary retention, the one year mortality was 4.1% in men aged 45-54 and 32.8% in those aged 85 and over. In 75 979 men with precipitated acute urinary retention, mortality was 9.5% and 45.4%, respectively. In men with spontaneous acute urinary retention aged 75-84, the most prevalent age group, the one year mortality was 12.5% in men without comorbidity and 28.8% in men with comorbidity. The corresponding figures for men with precipitated acute urinary retention were 18.1% and 40.5%. Compared with the general population, the highest relative increase in mortality was in men aged 45-54 (standardised mortality ratio 10.0 for spontaneous and 23.6 for precipitated acute urinary retention) and the lowest for men 85 and over (1.7 and 2.4, respectively). Conclusions Mortality in men admitted to hospital with acute urinary retention is high and increases strongly with age and comorbidity. Patients might benefit from multi-disciplinary care to identify and treat comorbid conditions.

The CUSUM chart method as a tool for continuous monitoring of clinical outcomes using routinely collected data.

BackgroundThe lack of robust systems for monitoring quality in healthcare has been highlighted. Statistical process control (SPC) methods, utilizing the increasingly available routinely collected electronic patient records, could be used in creating surveillance systems that could lead to rapid detection of periods of deteriorating standards. We aimed to develop and test a CUmulative SUM (CUSUM) based surveillance system that could be used in continuous monitoring of clinical outcomes, using routinely collected data. The low Apgar score (5 minute Apgar score < 7) was used as an example outcome.MethodA surveillance system based on the Observed minus Expected (O-E) as well as the 2-sided Log-Likelihood CUSUM charts was developed. The Log-Likelihood chart was designed to detect a 50% rise (deterioration) and halving (improvement) in the odds of low Apgar scores. Baseline rates were calculated from data for 2001 to 2004, and were used to monitor deliveries for 2005. Deliveries for nulliparous and multiparous women were monitored separately. All analyses were retrospective.ResultsThe CUSUM system detected periods of increased rates of low Apgar scores for each of the nulliparous and multiparous cohorts. The overall rate for 2005 was eventually found to be 0.67%, which was higher than the baseline reference rate of 0.44% from 2001 to 2004.ConclusionCUSUM methods can be used in continuous monitoring of clinical outcomes using routinely collected data. Used prospectively, they could lead to the prompt detection of periods of suboptimal standards.

Men's Preferences for Women's Breast Morphology in New Zealand, Samoa, and Papua New Guinea

Sexual selection via mate choice may have influenced the evolution of women’s breast morphology. We conducted an image-based questionnaire quantifying and comparing the preferences of men from Papua New Guinea (PNG), Samoa, and New Zealand (NZ) for images of women’s breast size, breast symmetry, areola size, and areolar pigmentation. Results showed that men from PNG preferred larger breasts to a greater extent than men from Samoa and NZ, providing some support for the hypothesis that men from subsistence living cultures have a greater preference for morphological cues indicative of caloric reserves. Symmetrical breasts were most attractive to men in each culture. However, preferences were highest among NZ men, followed by men from Samoa, and were lowest among men from PNG. These results did not support the hypothesis that people living in higher pathogen environments have a greater preference for traits indicative of pathogen resistance and developmental stability. Large areolae were preferred among men from PNG, and to a lesser extent in Samoa, while in NZ men preferred medium-sized areolae. Thus, men’s preferences for women’s areolar size appear to be highly culturally specific. Darkly pigmented areolae were most attractive to men from Samoa and PNG, whereas men from NZ preferred areolae with medium pigmentation. These findings suggest that areolar pigmentation indicative of sexual maturity is preferred by men rather than lighter pigmentation, which may signal that a woman is in the early years of reproductive maturity. This study highlights the importance of cross-cultural research when testing the role of morphological cues in mate choice.

Prospective evaluation of a continuous monitoring and quality-improvement system for reducing adverse neonatal outcomes

OBJECTIVE Our objective was to evaluate a prospective monitoring and quality improvement system for studying trends in the rates of an adverse neonatal outcome, the low Apgar scores (Apgar score <7). STUDY DESIGN A cumulative sum (CUSUM) chart-based system was used to monitor the rate of low Apgar scores over 2 years. Root cause analysis (RCA) was used to investigate for causes of periods of increased low Apgar score rates. RESULTS A period of deteriorated outcome (increased rates of low Apgar) occurred in August 2006. RCA identified deficiencies in cardiotocograph education, which were addressed by targeted training and mentoring. Prompt resolution followed, with the rates returning to baseline and staying within acceptable limits through to the end of evaluation in December 2007. CONCLUSION Prospective and continuous monitoring of clinical outcomes using the CUSUM chart method is feasible and may be beneficial. Early detection of an adverse trend allows for timely corrective action, and may lead to overall improvements in performance.

The UK scheme for mandatory continuous monitoring of early transplant outcome in all kidney transplant centers.

Mandatory continuous monitoring of early transplant outcome with centralized oversight was introduced in 2004 for all 23 UK adult kidney transplant units. Risk-adjusted cumulative sum charts are used to assess 30-day graft and patient survival against past performance for each center, and change in transplant center performance is assessed by tabular cumulative sum charts. The monitoring scheme has performed as predicted from simulations used to establish outcome thresholds and has been validated by comparison with 1- and 5-year outcome data for all UK transplant centers. The value and limitations of the scheme are discussed along with changes that may improve its utility as a tool for self-assessment and central oversight.

Creating functional groups of marine fish from categorical traits

Background Functional groups serve two important functions in ecology: they allow for simplification of ecosystem models and can aid in understanding diversity. Despite their important applications, there has not been a universally accepted method of how to define them. A common approach is to cluster species on a set of traits, validated through visual confirmation of resulting groups based primarily on expert opinion. The goal of this research is to determine a suitable procedure for creating and evaluating functional groups that arise from clustering nominal traits. Methods To do so, we produced a species by trait matrix of 22 traits from 116 fish species from Tasman Bay and Golden Bay, New Zealand. Data collected from photographs and published literature were predominantly nominal, and a small number of continuous traits were discretized. Some data were missing, so the benefit of imputing data was assessed using four approaches on data with known missing values. Hierarchical clustering is utilised to search for underlying data structure in the data that may represent functional groups. Within this clustering paradigm there are a number of distance matrices and linkage methods available, several combinations of which we test. The resulting clusters are evaluated using internal metrics developed specifically for nominal clustering. This revealed the choice of number of clusters, distance matrix and linkage method greatly affected the overall within- and between- cluster variability. We visualise the clustering in two dimensions and the stability of clusters is assessed through bootstrapping. Results Missing data imputation showed up to 90% accuracy using polytomous imputation, so was used to impute the real missing data. A division of the species information into three functional groups was the most separated, compact and stable result. Increasing the number of clusters increased the inconsistency of group membership, and selection of the appropriate distance matrix and linkage method improved the fit. Discussion We show that the commonly used methodologies used for the creation of functional groups are fraught with subjectivity, ultimately causing significant variation in the composition of resulting groups. Depending on the research goal dictates the appropriate strategy for selecting number of groups, distance matrix and clustering algorithm combination.

Evidence of separate subgroups of juvenile southern bluefin tuna

Abstract Archival tagging studies of southern bluefin tuna (SBT , Thunnus maccoyii) have revealed that juveniles residing in the Great Australian Bight (GAB) over the austral summer undertake seasonal cyclic migrations to the southeast Indian Ocean and the Tasman Sea during winter. However, there remains disagreement about the extent of mixing between juvenile SBT regularly caught by longline fleets south of Africa and those observed in the GAB. Some researchers have argued that archival tag recoveries indicate most juveniles reside in the GAB over the austral summer. Others have suggested that recoveries of conventional and archival tags are better explained by a juvenile population consisting of separate groups on the eastern and western sides of the Indian Ocean with limited intermixing. We present analyses of catch and tag recovery data and re‐examine archival tagging studies. The evidence provided strongly favors the hypothesis of separate juvenile subgroups, or contingents, with limited intermixing. We draw some tentative conclusions about the nature of the putative contingents and discuss some implications of these findings for the interpretation of existing datasets and future research priorities. We also provide the first evidence that the migration choices of juveniles that summer in the GAB are influenced by fidelity to winter feeding grounds and suggest this helps explain the collapse of the surface fishery off New South Wales in the 1980s.

Graphical model-based O/E control chart for monitoring multiple outcomes from a multi-stage healthcare procedure.

Most statistical process control programmes in healthcare focus on surveillance of outcomes at the final stage of a procedure, such as mortality or failure rates. Such an approach ignores the multi-stage nature of these procedures, in which a patient progresses through several stages prior to the final stage. In this paper, we introduce a novel approach to statistical process control programmes in healthcare. Our proposed approach is based on the regression adjustment and multi-stage control charts that have been in use in industrial applications for decades. Three advantages of the approach are: better understanding of how outcomes at different stages relate to each other, explicit monitoring of upstream stage outcomes may help curtail trends that lead to poorer end-stage outcomes and understanding the impact of each stage can help determine the most effective allocation of quality improvement resources. A test statistic for the control charts is proposed. Simulations are performed to test the control charts, and the results are summarised using an empirical probability of true detection. An illustrative example using data from a maternity unit is included. A main result from the simulation study is that taking a multi-stage approach makes it easer to explicitly identify shifts in upstream stage outcomes that might otherwise be signalled in final stage outcomes if dependence between stages is ignored.

Modeling Acute Rheumatic Fever

Acute rheumatic fever (ARF) is a major cause of heart disease, rare in developed countries, but of concern in New Zealand, where a unique feature is the prevalence of ARF among Maori and Pacific Island peoples. The incidence and prevalence of ARF in a population are modeled for the New Zealand case, where risks of contracting Group A Streptococcus or developing ARF are allowed to vary according to ethnicity, age, and ARF history. The critical parameter R0 determines whether a disease will become epidemic or not. A proportional treatment protocol is the most effective at reducing ARF.