Publications

BACKGROUND AND OBJECTIVES

Novel aptamer-based technologies can identify >7000 analytes per sample, offering a high-throughput alternative to traditional immunoassays in biomarker discovery. However, the specificity for distinct proteins has not been thoroughly studied in the context of CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We assessed the use of SOMAscan, an aptamer-based technology, for the quantification of eight immune activation biomarkers and cystatin C among 498 African American Study of Kidney Disease and Hypertension (AASK) participants using immunoassays as the gold standard. We evaluated correlations of serum proteins as measured by SOMAscan versus immunoassays with each other and with iothalamate-measured GFR. We then compared associations between proteins measurement with risks of incident kidney failure and all-cause mortality.

RESULTS

Six biomarkers (IL-8, soluble TNF receptor superfamily member 1B [TNFRSF1B], cystatin C, soluble TNF receptor superfamily member 1A [TNFRSF1A], IL-6, and soluble urokinase-type plasminogen activator receptor [suPAR]) had non-negligible correlations (=0.94, 0.93, 0.89, 0.85, 0.46, and 0.23, respectively) between SOMAscan and immunoassay measurements, and three (IL-10, IFN-, and TNF-) were uncorrelated (=0.08, 0.07, and 0.02, respectively). Of the six biomarkers with non-negligible correlations, TNFRSF1B, cystatin C, TNFRSF1A, and suPAR were negatively correlated with measured GFR and associated with higher risk of kidney failure. IL-8, TNFRSF1B, cystatin C, TNFRSF1A, and suPAR were associated with a higher risk of mortality both methods. On average, immunoassay measurements were more strongly associated with adverse outcomes than their SOMAscan counterparts.

CONCLUSIONS

SOMAscan is an efficient and relatively reliable technique for quantifying IL-8, TNFRSF1B, cystatin C, and TNFRSF1A in CKD and detecting their potential associations with clinical outcomes.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_02_23_CJN11700921.m….

BACKGROUND

Tubal ligation remains common in the USA, especially among low-income patients.

OBJECTIVE

To compare the effectiveness and safety of intrauterine contraceptives (IUC) to laparoscopic tubal ligation for Medicaid clients.

DESIGN

We partnered with patient and clinician stakeholders to conduct a retrospective cohort study using California Medicaid claims for patients who had an IUC placed or laparoscopic tubal ligation performed in 2008-2014, excluding procedures performed within 42 days of a birth. We applied log-linear (Poisson) event-history regression models for clustered person-period data to adjust for sociodemographic variables and pre-procedure health status when examining associations between these contraceptive procedures and claims related to contraceptive failure, complications, and pain in the first year post-procedure.

KEY RESULTS

We identified 35,705 patients who had a levonorgestrel IUC placed, 23,628 patients who had a copper IUC placed, and 23,965 patients who underwent laparoscopic tubal ligation. In unadjusted analyses, rates of pregnancy within 1 year were similar following levonorgestrel IUC (2.40%) or copper IUC placement (2.99%) or tubal ligation (2.64%). In adjusted analyses, compared to tubal ligation, pregnancy was less common following placement of a levonorgestrel IUC (adj IRR 0.72, 95% CI 0.64-0.82) and similar with placement of a copper IUC (adj IRR 0.92, 95% CI 0.82-1.05). Procedural complications such as infection (0.35% vs. 2.91%) were significantly less common with IUC placement than tubal ligation. Claims for pelvic and abdominal pain decreased in frequency with time since all procedures; 6 to 12 months post-procedure, pelvic pain claims were less common after levonorgestrel IUC (adj IRR 0.69, 95% CI 0.65-0.73) or copper IUC placement (adj IRR 0.70, 95% CI 0.66-0.75) than tubal ligation.

CONCLUSIONS

IUC appears at least as effective as laparoscopic tubal ligation at 1-year post-procedure with lower rates of infection and pelvic pain 6 to 12 months post-procedure.

CLINICAL TRIAL REGISTRATION

NCT03438682.