George J. Knafl

Use of Electronic Monitoring Devices to Measure Antiretroviral Adherence: Practical Considerations

The purpose of this paper is to describe electronic monitoring device (EMD) (e.g., MEMS caps) use among HIV-infected adults enrolled in a randomized clinical trial and to make explicit some of the benefits and caveats of using electronic monitoring device technology. This is a descriptive, exploratory study of EMD use among 128 HIV-infected adults treated with at least three antiretroviral agents. Thirty-six percent of the sample admitted that they did not use the EMD consistently. Forty-one percent of the subjects reported taking out more than one dose at a time and 26% reported opening the EMD but not taking the medication. Special subject-related issues accounted for only a small percentage of all reported problems with EMD use (e.g., transient housing, incarceration, substance abuse relapse and drug treatment). Results of this study suggest that EMDs may underestimate antiretroviral adherence among HIV-infected adults. Recommendations for improving EMD data quality are presented.

The transition to young adulthood in youth with type 1 diabetes on intensive treatment

Objective:  We sought to examine prospectively patterns of clinical and psychosocial outcomes during the transition from adolescence to young adulthood in a cohort initiating intensive therapy after the Diabetes Control and Complications Trial.

Factor analysis model evaluation through likelihood cross-validation

Medical research studies utilize survey instruments consisting of responses to multiple items combined into one or more scales. These studies can benefit from methods for evaluating those scales. Such an approach is presented for evaluating exploratory and confirmatory factor analysis models with decisions about covariance structure, including the number of factors, the factor extraction procedure, the allocation of survey items to summated scales and the extent of inter-scale dependence, made objectively using a likelihood-based form of cross-validation. This approach is demonstrated through example analyses using baseline data for three survey instruments from a clinical trial involving adolescents with type 1 diabetes.

Comparison of health-related quality of life questionnaires in ambulatory oncology

The purpose of this study is to compare three commonly used health-related quality of life (HR-QOL) questionnaires for their ease of use, accuracy, and patient preference; identify factors related to patient preference; identify differences in patient completion rates; and to identify factors associated with patient completion of these questionnaires. Three psychometrically sound measures, the Symptom Distress Scale (SDS), Medical Outcome Study Short Form-36 (SF-36), and Functional Assessment of Cancer Therapy (FACT), were tested. Seventy-nine patients completed questionnaires in the ambulatory oncology setting. No significant differences in patient ratings were found in ease of use and accuracy among the questionnaires. All of the questionnaires were rated as easy to use and accurate. Patient ratings on preference were marginally significant (p=0.07). Forty-six percent of participants indicated that they preferred the SDS, whereas 27 and 39 preferred the SF-36 and the FACT. No significant differences in patient completion rates were found among the questionnaires. One hundred percent completion rates ranged from 88.6 for the SDS to 78.5 for the SF-36, and 80 completion rates ranged from 98.7 for the SDS to 94.9 for the SF-36. Administration of standardized HR-QOL questionnaires is feasible in the clinical setting.

Class A biosolids production by a low-cost conventional technology

Encouraged by a finding that the pathogen analyses of numerous samples of the final product of the Metropolitan Water Reclamation District of Greater Chicago, Illinois (District), met the U.S. Environmental Protection Agency (U.S. EPA) Class A criteria, the District optimized and codified the operation of its sludge processing trains (SPTs), submitted a petition to the U.S. EPA Pathogen Equivalency Committee for obtaining certification of its SPTs as equivalent to a process to further reduce pathogens, and conducted a 3-year full-scale study. The objective of the study was to determine whether or not the Districts SPTs consistently produced a Class A biosolids final product. The primary conclusion drawn from this optimized and codified operation study was that all batches of the final air-dried product complied with the Class A criteria as specified by U.S. EPA in the Part 503 regulations.

Statistical evaluation of pathogen inactivation for a conventional low-cost technology Class A biosolids process

Statistical methods were developed for analyzing the results of a study of pathogen densities for sludge samples taken over the four stages of the solids processing trains (SPTs) operating at the Stickney and Calumet Water Reclamation Plants of the Metropolitan Water Reclamation District of Greater Chicago, Illinois (District). These methods also apply to pathogen density studies for other biosolids processes. Analysis of covariance models were used to estimate expected pathogen densities for individual solids processing stages. Cross-validation was used to select appropriate analysis of covariance models. Nonparametric methods were used to estimate distributions for pathogen density reductions between solids processing stages and to assess the effect of hypothetical surges and expansions in initial stage pathogen densities on final stage pathogen densities. These statistical analyses demonstrate that the Districts SPTs achieve target reductions in enteric virus and viable helminth ova densities with high probabilities. Furthermore, the Districts SPTs would still meet U.S. Environmental Protection Agency Class A restrictions for these pathogens with high probabilities, even if the initial stage pathogen densities observed in the study undergo extreme hypothetical surges or extreme hypothetical uniform expansions, that is, exceptionally large isolated bursts of pathogens or exceptionally large sustained increases in pathogens in the feed to the SPTs.