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Objective: To evaluate the effectiveness and health costs of a new primary care service delivery model (the Optimising Primary Care Management of Knee Osteoarthritis [PARTNER] model) to improve health outcomes for patients with knee osteoarthritis (OA) compared to usual care. Methods: This study was a 2‐arm, cluster, superiority, randomized controlled trial with randomization at the general practice level, undertaken in Victoria and New South Wales, Australia. We aimed to recruit 44 practices and 572 patients age ≥45 years with knee pain for >3 months. Professional development opportunities on best practice OA care were provided to intervention group general practitioners (GPs). All recruited patients had an initial GP visit to confirm knee OA diagnosis. Control patients continued usual GP care, and intervention patients were referred to a centralized care support team (CST) for 12‐months. Via telehealth, the CST provided OA education and an agreed OA action plan focused on muscle strengthening, physical activity, and weight management. Primary outcomes were patient self‐reported change in knee pain (Numerical Rating Scale [range 0–10; higher score = worse]) and physical function (Knee Injury and Osteoarthritis Outcome Score activities of daily living subscale [range 0–100; higher score = better] at 12 months. Health care cost outcomes included costs of medical visits and prescription medications over the 12‐month period. Results: Recruitment targets were not reached. A total of 38 practices and 217 patients were recruited. The intervention improved pain by 0.8 of 10 points (95% confidence interval [95% CI] 0.2, 1.4) and function by 6.5 of 100 points (95% CI 2.3, 10.7), more than usual care at 12 months. Total costs of medical visits and prescriptions were $3,940 (Australian) for the intervention group versus $4,161 for usual care. This difference was not statistically significant. Conclusion: The PARTNER model improved knee pain and function more than usual GP care. The magnitude of improvement is unlikely to be clinically meaningful for pain but is uncertain for function. [ABSTRACT FROM AUTHOR]

Objective: To report treatment patterns and survival outcomes of patients with relapsed and refractory metastatic germ cell tumours (GCTs) treated with high‐dose chemotherapy (HDCT) and autologous stem‐cell transplantation in low‐volume specialized centres within the widely dispersed populations of Australia and New Zealand between 1999 and 2019. Patients and Methods: We conducted a retrospective analysis of 111 patients across 13 institutions. Patients were identified from the Australasian Bone Marrow Transplant Recipient Registry. We reviewed treatment regimens, survival outcomes, deliverability and toxicities. Primary endpoints included overall (OS) and progression‐free survival (PFS). Cox proportional hazards models were used to test the association of survival outcomes with patient and treatment factors. Results: The median (range) age was 30 (14–68) years and GCT histology was non‐seminomatous in 84% of patients. International Prognostic Factors Study Group (IPFSG) prognostic risk category was very low/low, intermediate, high and very high in 18%, 36%, 25% and 21% of patients, respectively. Salvage conventional‐dose chemotherapy (CDCT) was administered prior to HDCT in 59% of patients. Regimens included paclitaxel, ifosfamide, carboplatin and etoposide (50%), carboplatin and etoposide (CE; 28%), carboplatin, etoposide and ifosfamide (CEI; 6%), carboplatin, etoposide and cyclophosphamide (CEC; 5%), CEC‐paclitaxel (6%) and other (5%). With a median follow‐up of 4.4 years, the 1‐, 2‐ and 5‐year PFS rates were 62%, 57% and 52%, respectively, and OS rates were 73%, 65% and 61%, respectively. There were five treatment‐related deaths. Progression on treatment occurred in 17%. In a univariable analysis, worse International Germ Cell Cancer Collaborative Group (IGCCCG) and IPFSG prognostic groups were associated with inferior survival outcomes. An association of inferior survival was not found with the number of high‐dose cycles received nor when HDCT was delivered after salvage CDCT. Conclusion: This large dual‐national registry‐based study reinforces the efficacy and deliverability of HDCT for relapsed and refractory metastatic GCT in low‐volume specialized centres in Australia and New Zealand, with survival outcomes comparable to those found in international practice. [ABSTRACT FROM AUTHOR]

In clinical trials one traditionally models the effect of treatment on the mean response. The underlying assumption is that treatment affects the response distribution through a mean location shift on a suitable scale, with other aspects of the distribution (shape/dispersion/variance) remaining the same. This work is motivated by a trial in Parkinson's disease patients in which one of the endpoints is the number of falls during a 10‐week period. Inspection of the data reveals that the Poisson‐inverse Gaussian (PiG) distribution is appropriate, and that the experimental treatment reduces not only the mean, but also the variability, substantially. The conventional analysis assumes a treatment effect on the mean, either adjusted or unadjusted for covariates, and a constant dispersion parameter. On our data, this analysis yields a non‐significant treatment effect. However, if we model a treatment effect on both mean and dispersion parameters, both effects are highly significant. A simulation study shows that if a treatment effect exists on the dispersion and is ignored in the modelling, estimation of the treatment effect on the mean can be severely biased. We show further that if we use an orthogonal parametrization of the PiG distribution, estimates of the mean model are robust to misspecification of the dispersion model. We also discuss inferential aspects that are more difficult than anticipated in this setting. These findings have implications in the planning of statistical analyses for count data in clinical trials. [ABSTRACT FROM AUTHOR]

Patients undergoing stem cell transplantation may require transfusion of units (bags) of packed red blood cells (PRBCs). Modelling of PRBC usage is important not only for prediction of transfusion requirements in future patients but also for its use as an inverse surrogate for engraftment, that is transplantation success. Inspection of PRBC unit usage reveals a strong preference for even numbers, which is caused by behavioural preference on the part of prescribing physicians. Digit preference is a phenomenon observed more commonly with self-reported data: typically survey respondents round recalled quantities such as the age at which a life event occurred to multiples of 5 or 10. In all cases, we can conceive of a latent variable, which has a smooth distribution, which is transformed via stochastic rules to a discrete variable with probability spikes at preferred digits. We propose a modelling framework based on a latent variable specification and stochastic transformation to the spiked distribution. Loglinear models for the mean of the process are implemented. Specification of the stochastic rules is important to success in accurate modelling of the process. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Quality of life (QOL) assessment is a key component of many clinical studies and frequently requires the use of single global summary measures that capture the overall balance of findings from a potentially wide-ranging assessment of QOL issues. We propose and evaluate an irregular multilevel latent variable model suitable for use as a global summary tool for health-related QOL assessments. The proposed model is a multiple indicator and multiple cause style of model with a two-level latent variable structure. We approach the modeling from a general multilevel modeling perspective, using a combination of random and nonrandom cluster types to accommodate the mixture of issues commonly evaluated in health-related QOL assessments-overall perceptions of QOL and health, along with specific psychological, physical, social, and functional issues. Using clinical trial data, we evaluate the merits and application of this approach in detail, both for mean global QOL and for change from baseline. We show that the proposed model generally performs well in comparing global patterns of treatment effect and provides more precise and reliable estimates than several common alternatives such as selecting from or averaging observed global item measures. A variety of computational methods could be used for estimation. We derived a closed-form expression for the marginal likelihood that can be used to obtain maximum likelihood parameter estimates when normality assumptions are reasonable. Our approach is useful for QOL evaluations aimed at pharmacoeconomic or individual clinical decision making and in obtaining summary QOL measures for use in quality-adjusted survival analyses. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

BACKGROUND: CD34+ cells infused predicts myeloid and platelet engraftment at the time of autologous stem cell transplantation. An association between the number of CD34+ cells infused and erythroid engraftment has yet to be established. STUDY DESIGN AND METHODS: Red blood cells transfused after autologous transplantation were compared with the number of CD34+ cells infused. Myeloid engraftment was assessed to confirm that normal engraftment kinetics occurred. RESULTS: Logistic regression established that the logarithm of the number of CD34+ cells infused (p = 0.0498) and admission hemoglobin (Hb; p < 0.001) predicted the need for transfusion. In those patients who required transfusion, standard regression methods were not valid. A novel model demonstrated that the initial Hb (p < 0.001) and diagnosis (p = 0.047) were significant predictors of transfusion requirements in patients needing transfusion. However, the number of CD34+ cells infused did not predict transfusion requirements in this group (p = 0.226). As myeloid engraftment demonstrated kinetics that have been previously described, it can be inferred that erythroid engraftment was not atypical. CONCLUSION: The number of CD34+ cells infused predicted the need for transfusion, although it did not predict the number of RBCs transfused in those patients having transfusion during their admission for autologous stem cell transplant. [ABSTRACT FROM AUTHOR]

The frequency of doctor consultations has direct consequences for health care budgets, yet little statistical analysis of the determinants of doctor visits has been reported. We consider the distribution of the number of visits to the doctor and, in particular, we model its dependence on a number of demographic factors. Examination of the Australian 1995 National Health Survey data reveals that generalized linear Poisson or negative binomial models are inadequate for modelling the mean as a function of covariates, because of excessive zero counts, and a mean-variance relationship that varies enormously over covariate values. A negative binomial model is used, with parameter values estimated in subgroups according to the discrete combinations of the covariate values. Smoothing splines are then used to smooth and interpolate the parameter values. In effect the mean and the shape parameters are each modelled as (different) functions of gender, age and geographical factors. The estimated regressions for the mean have simple and intuitive interpretations. However, the dependence of the (negative binomial) shape parameter on the covariates is more difficult to interpret and is subject to influence by extreme observations. We illustrate the use of the model by estimating the distribution of the number of doctor consultations in the Statistical Local Area of Ryde, based on population numbers from the 1996 census. [ABSTRACT FROM AUTHOR]

RTP is a widely used commercial real-time product that has been maintained over a period of 13 years. We have analyzed multiple versions of RTP, which is written in C and Assembler. We measured increases in dependencies within the code between successive versions and performed statistical analyses on the data. There was no significant difference between the maintenance of Assembler files and C files. Also, there was no significant difference between the versions written by the original developers and those written by maintenance programmers not involved in the original development. The differences between individual programmers were very highly significant. Our interpretation of these results is that the skill of the individual programmer is an important factor in ensuring that a software product remains maintainable over its lifetime and that software engineering education and training are therefore of major importance. [ABSTRACT FROM AUTHOR]

The article reviews the book "Generalized Linear Mixed Models: Modern Concepts, Methods and Applications" by W.W. Stroup.