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PubMed2005

PsN-Toolkit--a collection of computer intensive statistical methods for non-linear mixed effect modeling using NONMEM.

PsN-Toolkit is a collection of statistical tools for pharmacometric data analysis using the non-linear mixed effect modeling software NONMEM. The toolkit is object oriented and written in the programming language Perl using the programming library Perl-speaks-NONMEM (PsN). Five methods: the Bootstrap, the Jackknife, Log-likelihood Profiling, Case-deletion Diagnostics and Stepwise Covariate Model building are included as separate classes and may be used in user-written Perl scripts or through stand-alone command line applications. The tools are designed with the ability to cooperate and with an emphasis on common structures for workflow and result handling. Parallel execution of independent tool sections is supported on shared memory multiprocessor (SMP) computers, Mosix/openMosix clusters and distributed computing environments following the NorduGrid standard. In conclusion, PsN-Toolkit makes it easier to use the Bootstrap, the Jackknife, Log-likelihood Profiling, Case-deletion Diagnostics and Stepwise Covariate Model building in pharmacometric data analysis.

Cluster Analysis↗

PubMed2005

Mixed-effects modelling of the interspecies pharmacokinetic scaling of pegylated human erythropoietin.

The aim of this study was to develop a population pharmacokinetic model for interspecies allometric scaling of pegylated r-HuEPO (PEG-EPO) pharmacokinetics to man. A total of 927 serum concentrations from 193 rats, 6 rabbits, 34 monkeys, and 9 dogs obtained after a single dose of PEG-EPO, administered by the i.v. (dose range: 12.5-550 microg/kg) and s.c. (dose range: 12.5-500 microg/kg) routes, were pooled in this analysis. An open two-compartment model with first-order absorption and lag time (Tlag) and linear elimination from the central compartment was fitted to the data using the NONMEM V software. Body weight (WT) was used as a scaling factor and the effect of brain weight (BW), sex, and pregnancy status on the pharmacokinetic parameters was investigated. The final model was evaluated by means of a non-parametric bootstrap analysis and used to predict the PEG-EPO pharmacokinetic parameters in healthy male subjects. The systemic clearance (CL) in males was estimated to be 4.08WT1.030xBW-0.345 ml/h. In females, the CL was 90.7% of the CL in males. The volumes of the central (Vc) and the peripheral (Vp) compartment were characterized as 57.8WT0.959 ml, and 48.1WT1.150 ml, respectively. Intercompartmental flow was estimated at 2.32WT0.930 ml/h. Absorption rate constant (Ka) was estimated at 0.0538WT-0.149. The absolute s.c. bioavailability F was calculated at 52.5, 80.2, and 49.4% in rat, monkey, and dog, respectively. The interindividual variability in the population pharmacokinetic parameters was fairly low (<35%). Non-parametric bootstrap confirmed the accuracy of the NONMEM estimates. The mean model predicted pharmacokinetic parameters in healthy male subjects of 70 kg were estimated at: CL: 26.2 ml/h; Vc: 3.6l; Q: 286 l/h; Vp: 6.9l, and Ka: 0.031 h-1. The population pharmacokinetic model developed was appropriate to describe the time course of PEG-EPO serum concentrations and their variability in different species. The model predicted pharmacokinetics of PEG-EPO in humans suggest a less frequent dosing regimen relative to erythropoietin and darbepoetin, potentially leading to a simplification of anemia management.

Animals↗

PubMed2006

Estimating dietary consumption patterns among children: a comparison between cross-sectional and longitudinal study designs.

Estimating dietary intake for children is an essential component of conducting pesticide exposure assessments given the fact that children are predominantly exposed to certain pesticides, such as organophosphorus pesticide, through dietary intake. Different study designs and their respective sampling methodology utilized to estimate food consumption patterns can significantly alter the parameter estimates and the variability in the values obtained. This study investigated the impacts of study design on overall estimates of dietary intake by applying the temporal sampling characteristics used in cross-sectional approaches, as in The Continuing Survey of Food for Intakes by Individuals (CSFII), to food consumption data collected in a longitudinal manner via a bootstrap sampling technique. We examined the precision of time-averaged dietary intake estimates under various sampling schemes and explored the contribution of seasonality toward the dietary patterns. A comparison between the estimates of food consumption obtained from the bootstrap replicates and the longitudinal study estimates indicate that variability is significantly decreased when employing a longitudinal study design. Moreover, both between and within-subject variability decreases when individuals are followed over an increasing number of days. Finally, within the longitudinal study cohort, we observed a seasonal component to dietary intake for fruits and grains. Our findings suggest that longitudinal dietary surveys offer substantial improvements for exposure assessment compared to a standard cross-sectional design.

Child↗

PubMed2005

Development and internal validation of a nomogram predicting the probability of prostate cancer Gleason sum upgrading between biopsy and radical prostatectomy pathology.

OBJECTIVE: Previous reports indicate that as many as 43% of men with low grade PCa at biopsy will be diagnosed with high-grade PCa at RP. We explored the rate of upgrading from biopsy to RP specimen in our contemporary cohort, and developed a model capable of predicting the probability of biopsy Gleason sum upgrading. MATERIALS AND METHODS: The study cohort consisted of 2982 men treated with RP, with available clinical stage, serum prostate specific antigen and biopsy Gleason scores. These clinical data were used as predictors in multivariate logistic regression models (LRM) addressing the rate of Gleason sum upgrading between biopsy and RP pathology. LRM regression coefficients were used to develop a nomogram predicting the probability of Gleason sum upgrading and was subjected to 200 bootstrap resamples for internal validation and to reduce overfit bias. RESULTS: Overall, 875 patients were upgraded (29.3%). In multivariate LRMs, all predictors were highly significant (all p values <0.0001). Bootstrap-corrected predictive accuracy of the nomogram predicting the probability of Gleason sum upgrading between biopsy and RP was 0.804. CONCLUSION: We developed a highly accurate clinical aid for treatment decision-making. It may prove useful when the possibility of a more aggressive Gleason variant may change the treatment options.

Biopsy↗

PubMed2006

Pre-treatment nomogram for disease-specific survival of patients with chemotherapy-naive androgen independent prostate cancer.

OBJECTIVE: Our objective was to develop a nomogram that predicts the probability of cancer-specific survival in men with untreated androgen-independent prostate cancer (AIPC). METHODS: AIPC was diagnosed in 129 consecutive patients between 1989 and 2002. No patient received cytotoxic chemotherapy. Univariate and multivariate Cox regression models were used to test the association between prostate-specific antigen (PSA) level at initiation of androgen deprivation, PSA doubling time (PSADT), PSA nadir on androgen deprivation therapy (ADT), time from ADT to AIPC, and AIPC-specific mortality. Multivariate regression coefficients were then used to develop a nomogram predicting AIPC-specific survival at 12-60 mo after AIPC diagnosis. Two-hundred bootstrap resamples were used to internally validate the nomogram. RESULTS: AIPC-specific mortality was recorded in 74 of 129 patients (57.4%). Other-cause mortality was recorded in 7 men (5.4%). Median overall survival was 52.0 mo (mean, 36.0 mo) and median AIPC-specific survival was 54.0 mo (mean, 35.0 mo). In univariate regression models, all variables were significant predictors of AIPC-specific survival (p < or = 0.02). In multivariate models, PSADT and time from androgen deprivation to AIPC remained statistically significant (p < or = 0.004). Bootstrap-corrected predictive accuracy of the nomogram was 80.9% versus 74.9% for our previous model. CONCLUSIONS: A nomogram predicting AIPC-specific survival is between 13% and 14% more accurate than previous nomograms and 6% more accurate than tree regression-based predictions obtained from the same data. Moreover, a nomogram approach combines several advantages, such as user-friendly interface and precise estimation of individual recurrence probability at several time points after AIPC diagnosis, which all patients deserve to know and all treating physicians need to know.

Aged↗

PubMed2006

Validation of a nomogram predicting the probability of lymph node invasion among patients undergoing radical prostatectomy and an extended pelvic lymphadenectomy.

INTRODUCTION: Our goal was to develop and internally validate a nomogram for prediction of lymph node invasion (LNI) in patients with clinically localized prostate cancer undergoing extended pelvic lymphadenectomy (ePLND). METHODS: 602 consecutive patients (mean age 65.8 years) underwent an ePLND, where 10 or more nodes were removed. PSA was 1.1-49.9 (median 7.2). Clinical stages were: T1c in 55.6%, T2 in 41.4% and T3 in 3%. Biopsy Gleason sums were: 6 or less in 66%, 7 in 25.4%, 8-10 in 8.6%. Multivariate logistic regression models tested the association between all of the above predictors and LNI. Regression-based coefficients were used to develop a nomogram predicting LNI and 200 bootstrap resamples were used for internal validation. RESULTS: Mean number of lymph nodes removed was 17.1 (range 10-40). LNI was detected in 66 patients (11.0%). Univariate predictive accuracy for total PSA, clinical stage and biopsy Gleason sum was 63%, 58% and 73%, respectively. A nomogram based on clinical stage, PSA and Biopsy Gleason sum demonstrated bootstrap-corrected predictive accuracy of 76%. CONCLUSIONS: A nomogram based on pre-treatment PSA, clinical stage and biopsy Gleason sum can highly accurately predict LNI at ePLND.

Aged↗

PubMed2006

A comparison of methods for ERP assessment in a P300-based GKT.

P300-based GKT (guilty knowledge test) has been suggested as an alternative approach for conventional polygraphy. The purpose of this study is to evaluate three classifying methods for this approach and compare their performances in a lab analogue. Several subjects went through the designed GKT paradigm and their respective brain signals were recorded. For the analysis of signals, BAD (bootstrapped amplitude difference) and BCD (bootstrapped correlation difference) methods as two predefined methods alongside a new approach consisting of wavelet features and a statistical classifier were implemented. The rates of correct detection in guilty and innocent subjects were 74-80%. The results indicate the potential of P300-based GKT for detecting concealed information, although further research is required to increase its accuracy and precision and evaluating its vulnerability to countermeasures.

Electroencephalography↗

PubMed2006

Dose-volume modeling of the risk of postoperative pulmonary complications among esophageal cancer patients treated with concurrent chemoradiotherapy followed by surgery.

PURPOSE: The aim of this study was to investigate the effect of radiation dose distribution in the lung on the risk of postoperative pulmonary complications among esophageal cancer patients. METHODS AND MATERIALS: We analyzed data from 110 patients with esophageal cancer treated with concurrent chemoradiotherapy followed by surgery at our institution from 1998 to 2003. The endpoint for analysis was postsurgical pneumonia or acute respiratory distress syndrome. Dose-volume histograms (DVHs) and dose-mass histograms (DMHs) for the whole lung were used to fit normal-tissue complication probability (NTCP) models, and the quality of fits were compared using bootstrap analysis. RESULTS: Normal-tissue complication probability modeling identified that the risk of postoperative pulmonary complications was most significantly associated with small absolute volumes of lung spared from doses > or = 5 Gy (VS5), that is, exposed to doses < 5 Gy. However, bootstrap analysis found no significant difference between the quality of this model and fits based on other dosimetric parameters, including mean lung dose, effective dose, and relative volume of lung receiving > or = 5 Gy, probably because of correlations among these factors. The choice of DVH vs. DMH or the use of fractionation correction did not significantly affect the results of the NTCP modeling. The parameter values estimated for the Lyman NTCP model were as follows (with 95% confidence intervals in parentheses): n = 1.85 (0.04, infinity), m = 0.55 (0.22, 1.02), and D50 = 17.5 Gy (9.4 Gy, 102 Gy). CONCLUSIONS: In this cohort of esophageal cancer patients, several dosimetric parameters including mean lung dose, effective dose, and absolute volume of lung receiving < 5 Gy provided similar descriptions of the risk of postoperative pulmonary complications as a function of the radiation dose distribution in the lung.

Analysis of Variance↗

PubMed2005

Long-term cost effectiveness of early and sustained dual oral antiplatelet therapy with clopidogrel given for up to one year after percutaneous coronary intervention results: from the Clopidogrel for the Reduction of Events During Observation (CREDO) trial.

OBJECTIVES: This study sought to evaluate the long-term cost effectiveness of a clopidogrel loading strategy before percutaneous coronary intervention (PCI) followed by continued treatment for one year. BACKGROUND: The Clopidogrel for the Reduction of Events During Observation (CREDO) trial, a randomized trial of 2,116 patients, showed the effectiveness of antiplatelet therapy with clopidogrel 300 mg before PCI and 75 mg daily for one year afterward compared with placebo load and placebo days 29 to 365 in reducing the combined risk of death, myocardial infarction, and stroke. All patients received clopidogrel on days 1 to 28 and aspirin on days 1 to 365. METHODS: All hospitalizations were assigned a diagnosis-related group. Associated costs were estimated three ways (including professional costs): 1) Medicare costs, 2) MEDSTAT costs, and 3) blend with Medicare for those age > or = 65 years and MEDSTAT for those age <65 years. Clopidogrel 75 mg cost 3.22 dollars. Life expectancy in trial survivors was estimated using external data. Confidence intervals were assessed by bootstrap. RESULTS: The primary composite end point occurred in 89 (8.45%) clopidogrel patients and in 122 (11.48%) placebo patients (relative risk reduction [RRR] 26.9%; 95% confidence interval [CI] 3.9% to 44.4%). The number of life-years gained (LYG) with clopidogrel was 0.1526 (95% CI 0.0263 to 0.2838) using Framingham data and 0.1920 (95% CI 0.054 to 0.337) using Saskatchewan data. Average total costs were 664 dollars higher for the clopidogrel arm (95% CI -461 dollars to 1,784 dollars). The incremental cost-effectiveness ratios (ICERs) based on Framingham data ranged from 3,685 dollars/LYG to 4,353 dollars/LYG, with over 97% of bootstrap-derived ICER estimates below 50,000 dollars/LYG. The ICERs based on Saskatchewan data were 2,929 dollars/LYG to 3,460 dollars/LYG, with over 98% of estimates below 50,000 dollars/LYG. CONCLUSIONS: Platelet inhibition with clopidogrel loading before PCI followed by therapy for one year is highly cost effective.

Aspirin↗

PubMed2006

Small-scale randomized controlled trials need more powerful methods of mediational analysis than the Baron-Kenny method.

OBJECTIVE: To devise more-effective physical activity interventions, the mediating mechanisms yielding behavioral change need to be identified. The Baron-Kenny method is most commonly used, but has low statistical power and may not identify mechanisms of behavioral change in small-to-medium size studies. More powerful statistical tests are available. STUDY DESIGN AND SETTING: Inactive adults (N=52) were randomized to either a print or a print-plus-telephone intervention. Walking and exercise-related social support were assessed at baseline, after the intervention, and 4 weeks later. The Baron-Kenny and three alternative methods of mediational analysis (Freedman-Schatzkin; MacKinnon et al.; bootstrap method) were used to examine the effects of social support on initial behavior change and maintenance. RESULTS: A significant mediational effect of social support on initial behavior change was indicated by the MacKinnon et al., bootstrap, and, marginally, Freedman-Schatzkin methods, but not by the Baron-Kenny method. No significant mediational effect of social support on maintenance of walking was found. CONCLUSIONS: Methodologically rigorous intervention studies to identify mediators of change in physical activity are costly and labor intensive, and may not be feasible with large samples. The use of statistically powerful tests of mediational effects in small-scale studies can inform the development of more effective interventions.

Aged↗

PubMed2004

Estimating medical care costs under conditions of censoring.

A number of non-parametric estimators have been proposed to calculate average medical care costs in the presence of censoring. This paper assesses their performance both in terms of bias and efficiency under extreme conditions using a medical dataset which exhibits heavy censoring. The estimators are further investigated using artificially generated data. Their variances are derived from analytic formulae based on the estimators' asymptotic properties and these are compared to empirically derived bootstrap estimates. The analysis revealed various performance patterns ranging from generally stable estimators under all conditions considered to estimators which become increasingly unstable with increasing levels of censoring. The bootstrap estimates of variance were consistent with the analytically derived asymptotic variance estimates. Of the two estimators that performed best, one imposes restrictions on the censoring distribution while the other is not restricted by the censoring pattern and on this basis the second may be preferred.

Costs and Cost Analysis↗

PubMed2026

Exploring precision risk in pediatric vesicoureteral reflux: Innate immune gene variations and reflux outcomes in the RIVUR cohort.

INTRODUCTION: Children with vesicoureteral reflux (VUR) are at increased risk for morbidity from recurrent urinary tract infections (UTIs), yet the factors influencing spontaneous VUR resolution remain poorly defined. This study evaluates whether genetic variations in key urinary innate immune effectors (DEFA1A3, DMBT1, and RNASE7) influences VUR resolution and interacts with prophylaxis to alter clinical response. METHODS: We conducted a secondary analysis of 303 RIVUR participants with available DEFA1A3 and DMBT1 copy number variation (CNV) data and RNASE7 rs1263872 genotype. Primary outcomes were (1) VUR improvement (decrease in grade) and (2) VUR resolution at study exit. Multivariable logistic regression models included genotype, treatment, and their interactions, adjusting for age, sex, baseline grade (high vs low), laterality, bowel/bladder dysfunction, and any UTI. Internal validation used 2000-sample bootstrap with bias-corrected and accelerated confidence intervals and influence diagnostics. RESULTS: Clinical covariates did not significantly predict VUR improvement. Children with DEFA1A3 CNV >5 had higher odds of improvement (OR 2.36, 95% CI 1.12-4.96, p = 0.023), an effect that remained significant in bootstrap analyses. High-grade VUR was associated with lower odds of resolution (OR 0.34, 95% CI 0.12-0.94, p = 0.038). A significant interaction was observed between prophylaxis and high DMBT1 copy number for VUR resolution (interaction OR 2.99, 95% CI 1.11-8.04, p = 0.031); no interaction was seen for improvement. RNASE7 rs1263872 was not associated with either outcome. CONCLUSION: Innate immune gene variation may contribute to heterogeneity in VUR outcomes. High DEFA1A3 copy number was associated with reflux improvement and a DMBT1-prophylaxis interaction was associated with reflux resolution. The results of this study is hypothesis-generating and prompt further evaluation to assess whether a subset of children may experience structural benefit from prophylaxis or have a more favorable natural history based on their innate immune genotype.

Humans↗

PubMed2006

Risk-adjusted morbidity and mortality models to compare the performance of two units after major lung resections.

OBJECTIVE: We sought to develop risk-adjusted morbidity and mortality models to compare the performance of 2 different thoracic surgery units in patients submitted to major lung resections. METHODS: Seven hundred forty-three patients (551 male and 192 female patients) who underwent lobectomy (n = 611) or pneumonectomy (n = 132) from January 2000 through August 2004 at 2 European thoracic units (519 patients in unit A and 224 patients in unit B) were analyzed. Risk-adjusted models of 30-day or in-hospital cardiopulmonary morbidity and mortality were developed by using stepwise logistic regression analyses and validated by means of bootstrap analysis. Preoperative and operative variables were initially screened by using univariate analysis. Those with a P value of less than .10 were used as independent variables in the regression analyses. The regression equations were then used to estimate the risk of outcome, and the observed and predicted outcome rates of the 2 units were compared by using the z test for comparison of proportions. RESULTS: The following regression models were developed. Predicted morbidity: lnR/1-R=-2.4+0.03Xage-0.02XppoFEV1+0.6Xcardiaccomorbidity (Hosmer-Lemeshow statistic = 6.1 [P = .6], c index = 0.65). Predicted mortality: lnR/1-R=-6.97+0.095Xage-0.042XppoFEV1 (Hosmer-Lemeshow statistic = 2.99 [P = .9], c index = 0.77). The models proved to be stable at bootstrap analyses. No differences were noted between observed and predicted outcome rates within each unit, despite an apparent unadjusted better performance of unit B. CONCLUSIONS: The use of risk-adjusted outcome models avoided misleading information derived from the unadjusted analysis of performance. Risk modeling is essential for the evaluation of the quality of care.

Aged↗

PubMed2006

Nomogram for predicting disease recurrence after radical cystectomy for transitional cell carcinoma of the bladder.

PURPOSE: American Joint Committee on Cancer staging represents the gold standard for prediction of recurrence after radical cystectomy in patients with invasive bladder cancer. We tested the hypothesis that American Joint Committee on Cancer stage based predictions may be improved when pathological tumor and node stage information is combined with additional clinical and pathological variables within a prognostic nomogram. MATERIALS AND METHODS: We used Cox proportional hazards regression analysis to model variables of 728 patients with transitional cell carcinoma of the bladder treated with radical cystectomy and bilateral pelvic lymphadenectomy at 1 of 3 participating institutions. Standard predictors, pT and pN, were complemented by age, gender, tumor grade at cystectomy, presence of lymphovascular invasion, presence of carcinoma in situ in the cystectomy specimen, neoadjuvant chemotherapy, adjuvant chemotherapy and adjuvant radiotherapy. The concordance index was used to quantify the accuracy of regression coefficient based nomograms. A total of 200 bootstrap resamples were used to reduce overfit bias and for internal validation. Calibration plots were used to graphically explore the performance characteristics of the multivariate nomogram. RESULTS: Followup ranged from 0.1 to 183.4 months (median 24.9, mean 36.4). Recurrence was recorded in 249 (34.2%) patients with a median time to recurrence of 108 months (range 0.8 to 131.9). Actuarial recurrence-free probabilities were 69.6% (95% CI 65.8%-73.0%), 60.2% (55.8%-64.3%) and 52.9% (47.3%-58.1%) at 2, 5 and 8 years after cystectomy, respectively. Two-hundred bootstrap corrected predictive accuracy of American Joint Committee on Cancer stage based predictions was 0.748. Accuracy increased by 3.2% (0.780) when age, lymphovascular invasion, carcinoma in situ, neoadjuvant chemotherapy, adjuvant chemotherapy and adjuvant radiotherapy were added to pathological stage information and used within a nomogram. CONCLUSIONS: A nomogram predicting bladder cancer recurrence after cystectomy is 3.2% more accurate than American Joint Committee on Cancer stage based predictions. Moreover, a nomogram approach combines several advantages such as easy and precise estimation of individual recurrence probability at key points after cystectomy, which all patients deserve to know and all treating physicians need to know.

Adult↗

PubMed2006

Preoperative nomograms for predicting stone-free rate after extracorporeal shock wave lithotripsy.

PURPOSE: Extracorporeal shock wave lithotripsy is currently accepted as a first line treatment modality for urolithiasis. In obtaining informed consent it is important to inform patients of the stone-free rate with extracorporeal shock wave lithotripsy before surgery. The present study was performed to develop preoperative nomograms for predicting stone-free rates after extracorporeal shock wave lithotripsy. MATERIALS AND METHODS: A total of 435 patients with 507 urinary stones were treated with extracorporeal shock wave lithotripsy with a Dornier Lithotripter D. Patient age, sex, body mass index, number of stone(s) in each treatment, stone length, side and location were evaluated before extracorporeal shock wave lithotripsy, and treatment efficacies were evaluated at 3 months after each session. The treated stones were divided into 2 groups, those in cases that were stone-free with a single extracorporeal shock wave lithotripsy session and those in all other cases. Multivariate analysis was performed using a logistic regression model. The nomograms were developed by repeating the analysis on 200 bootstrap samples. RESULTS: Stone length, location and number were identified as significant variables on multivariate analysis, and a logistic regression model was developed using these variables. The nomograms predicting stone-free rate at 3 months after single extracorporeal shock wave lithotripsy treatment were finally developed from 200 bootstrap samples. In these nomograms the stone-free probability was highest for solitary proximal ureteral stones less than 5 mm in size (93.8%) and lowest for multiple caliceal stones greater than 21 mm (10.5%). CONCLUSIONS: This study demonstrated that stone size, location and number are significant predictors of extracorporeal shock wave lithotripsy outcome. We have developed nomograms for predicting the stone-free rate of extracorporeal shock wave lithotripsy, which is useful for counseling patients with urolithiasis before surgery.

Female↗

PubMed2006

Assessing self organizing maps via contiguity analysis.

Contiguity analysis is a straightforward generalization of linear discriminant analysis in which the partition of elements is replaced by a more general graph structure. Applied to the graph induced by a Self Organizing Map (SOM), contiguity analysis provides a set of linear projectors leading to a planar representation as close as possible to the SOM. As expected, such projectors may only concern local parts of the SOMs. They allow us to visualize the shapes of the clusters (convex hulls of the projections of the elements belonging to a cluster) and the pattern of the elements within each cluster. In some contexts, it is possible to project the bootstrap replicates of the elements, and therefore to produce confidence areas for elements via a standard partial bootstrap procedure.

Algorithms↗

PubMed2004

Partial least squares analysis of neuroimaging data: applications and advances.

Partial least squares (PLS) analysis has been used to characterize distributed signals measured by neuroimaging methods like positron emission tomography (PET), functional magnetic resonance imaging (fMRI), event-related potentials (ERP) and magnetoencephalography (MEG). In the application to PET, it has been used to extract activity patterns differentiating cognitive tasks, patterns relating distributed activity to behavior, and to describe large-scale interregional interactions or functional connections. This paper reviews the more recent extension of PLS to the analysis of spatiotemporal patterns present in fMRI, ERP, and MEG data. We present a basic mathematical description of PLS and discuss the statistical assessment using permutation testing and bootstrap resampling. These two resampling methods provide complementary information of the statistical strength of the extracted activity patterns (permutation test) and the reliability of regional contributions to the patterns (bootstrap resampling). Simulated ERP data are used to guide the basic interpretation of spatiotemporal PLS results, and examples from empirical ERP and fMRI data sets are used for further illustration. We conclude with a discussion of some caveats in the use of PLS, including nonlinearities, nonorthogonality, and interpretation difficulties. We further discuss its role as an important tool in a pluralistic analytic approach to neuroimaging.

Adult↗

PubMed2026

Mobile health apps improve Health-Related Quality of Life in Type 2 Diabetes Mellitus by enhancing medication adherence: A multicentre randomised controlled trial with mediation analysis.

AIMS: This study evaluated whether a gamified mHealth application (CareAide®) improves Health-Related Quality of Life (HRQoL) in Type 2 Diabetes Mellitus (T2DM) and whether this effect is mediated by medication adherence. METHODS: Prespecified secondary analysis of the T2DM cohort from a 6-month multicentre RCT (NCT06068309; N = 663; three Malaysian hospitals). Participants were randomised 1:1 to standard care or CareAide®. Adherence (MMAS-8), EQ-5D-5L utility (Malaysian value set), and AQoL-6D were assessed at baseline and 6 months. Simple mediation analysis (PROCESS Model 4; 5000 bootstraps) adjusted for baseline HRQoL. RESULTS: CareAide® significantly predicted higher MMAS-8 scores (mean difference +1.756; d = 1.638; p < 0.001). Higher MMAS-8 scores significantly predicted improved AQoL-6D utility (b = 0.024; p < 0.001). The direct effect on AQoL-6D was non-significant (p = 0.248). Bootstrapped indirect effect confirmed full mediation via AQoL-6D (0.042; 95% CI [0.024, 0.060]). A sensitivity analysis adjusting for baseline HbA1c confirmed full mediation (indirect = 0.034; 95% CI [0.015, 0.052]; n = 563). EQ-5D-5L utility showed a significant direct between-group difference at 6 months (p = 0.012) but did not operate as a mediation outcome. CONCLUSIONS: Medication adherence fully mediates the AQoL-6D HRQoL benefit of a gamified mHealth intervention in T2DM, as confirmed by both the primary and HbA1c-adjusted sensitivity analyses. These findings support integration of behaviourally informed digital adjuncts into routine primary diabetes care.

Humans↗