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Randomized controlled trials in CKD lag in number behind those of other chronic diseases, despite the high morbidity and mortality experienced by patients with kidney disease and the exorbitant costs of their health care. Observational studies of CKD frequently yield seemingly paradoxic associations of traditional risk factors with outcomes, making it difficult to extrapolate the results of trials conducted in people with normal kidney function to patients with CKD. However, many completed trials in CKD have been limited by intermediate outcomes of unclear clinical significance or narrow eligibility criteria that limit external validity, and implementation of proven therapies remains a challenge. It is therefore imperative that the nephrology community capitalize on recent interest in novel approaches to trial design, such as pragmatic clinical trials. These trials are meant to promote research within real world settings to yield clinically relevant results with greater applicability than those of traditional trials, while maintaining many advantages, such as controlling for potential sources of bias. We provide a description of pragmatic clinical trials and a discussion of advantages, disadvantages, and practical challenges inherent to this study design, in the context of specific scientific questions relevant to patients with CKD.

BACKGROUND

Tenofovir disoproxil fumarate (TDF) can cause proximal tubular damage and chronic kidney disease in human immunodeficiency virus (HIV)-infected individuals. Urine α1-microglobulin (A1M), a low-molecular-weight protein indicative of proximal tubular dysfunction, may enable earlier detection of TDF-associated tubular toxicity.

STUDY DESIGN

Cross-sectional.

SETTING & PARTICIPANTS

883 HIV-infected and 350 -uninfected men enrolled in the Multicenter AIDS Cohort Study.

PREDICTORS

HIV infection and TDF exposure.

OUTCOME

Urine A1M level.

RESULTS

Urine A1M was detectable in 737 (83%) HIV-infected and 202 (58%) -uninfected men (P<0.001). Among HIV-infected participants, 573 (65%) were current TDF users and 112 (13%) were past TDF users. After multivariable adjustment including demographics, traditional kidney disease risk factors, and estimated glomerular filtration rate, HIV infection was associated with 136% (95% CI, 104%-173%) higher urine A1M levels and 1.5-fold (95% CI, 1.3- to 1.6-fold) prevalence of detectable A1M. When participants were stratified by TDF exposure, HIV infection was associated with higher adjusted A1M levels, by 164% (95% CI, 127%-208%) among current users, 124% (95% CI, 78%-183%) among past users, and 76% (95% CI, 45%-115%) among never users. Among HIV-infected participants, each year of cumulative TDF exposure was associated with 7.6% (95% CI, 5.4%-9.9%) higher A1M levels in fully adjusted models, a 4-fold effect size relative to advancing age (1.8% [95% CI, 0.9%-2.7%] per year). Each year since TDF treatment discontinuation was associated with 4.9% (95% CI, -9.4%--0.2%) lower A1M levels among past users.

LIMITATIONS

Results may not be generalizable to women.

CONCLUSIONS

HIV-infected men had higher urine A1M levels compared with HIV-uninfected men. Among HIV-infected men, cumulative TDF exposure was associated with incrementally higher A1M levels, whereas time since TDF treatment discontinuation was associated with progressively lower A1M levels. Urine A1M appears to be a promising biomarker for detecting and monitoring TDF-associated tubular toxicity.

Background. Millions of people are infected with hepatitis C virus (HCV) worldwide and 30% spontaneously clear the infection. Reasons for HCV clearance without antiviral treatment are not well understood. Methods. Blood was collected for DNA analysis from patients with chronic HCV infection or evidence of spontaneous clearance. To overcome anticipated limitations of small sample size, primary analyses consisted of a candidate gene analysis of 12 preselected genes based on known association with host immunologic response to HCV infection. To further reduce the impact of multiple testing on power, a single likelihood ratio test was conducted for each gene using all associated SNPs assayed on the Illumina Quad 610/660W chip. Step-down permutation methods were used to adjust for multiple testing in all analyses. Results. Ninety-five and 62 patients with HCV chronic infection or spontaneous clearance, respectively, were included for analysis. HLA-DQB1 (p = 1.76⁎10(-5)) and IL-6 (p = 0.0007) genes were significantly associated with spontaneous HCV clearance. IL-28B was not significantly associated with spontaneous clearance (p = 0.17). Conclusion. Our whole-gene analytic strategy identified a previously unreported association of IL-6 with spontaneous clearance of HCV infection. We also confirmed the finding that HLA-DQB1 is associated with spontaneous resolution of HCV infection.