Severe Hypocalcemia With Denosumab Among Older Female Dialysis-Dependent Patients

Importance

Dialysis-dependent patients experience high rates of morbidity from fractures, yet little evidence is available on optimal treatment strategies. Chronic kidney disease-mineral and bone disorder is nearly universal in dialysis-dependent patients, complicating diagnosis and treatment of skeletal fragility.

Objective

To examine the incidence and comparative risk of severe hypocalcemia with denosumab compared with oral bisphosphonates among dialysis-dependent patients treated for osteoporosis.

Design, Setting, and Participants

Retrospective cohort study of female dialysis-dependent Medicare patients aged 65 years or older who initiated treatment with denosumab or oral bisphosphonates from 2013 to 2020. Clinical performance measures including monthly serum calcium were obtained through linkage to the Consolidated Renal Operations in a Web-Enabled Network database.

Exposures

Denosumab, 60 mg, or oral bisphosphonates.

Main Outcomes and Measures

Severe hypocalcemia was defined as total albumin-corrected serum calcium below 7.5 mg/dL (1.88 mmol/L) or a primary hospital or emergency department hypocalcemia diagnosis (emergent care). Very severe hypocalcemia (serum calcium below 6.5 mg/dL [1.63 mmol/L] or emergent care) was also assessed. Inverse probability of treatment-weighted cumulative incidence, weighted risk differences, and weighted risk ratios were calculated during the first 12 treatment weeks.

Results

In the unweighted cohorts, 607 of 1523 denosumab-treated patients and 23 of 1281 oral bisphosphonate-treated patients developed severe hypocalcemia. The 12-week weighted cumulative incidence of severe hypocalcemia was 41.1% with denosumab vs 2.0% with oral bisphosphonates (weighted risk difference, 39.1% [95% CI, 36.3%-41.9%]; weighted risk ratio, 20.7 [95% CI, 13.2-41.2]). The 12-week weighted cumulative incidence of very severe hypocalcemia was also increased with denosumab (10.9%) vs oral bisphosphonates (0.4%) (weighted risk difference, 10.5% [95% CI, 8.8%-12.0%]; weighted risk ratio, 26.4 [95% CI, 9.7-449.5]).

Conclusions and Relevance

Denosumab was associated with a markedly higher incidence of severe and very severe hypocalcemia in female dialysis-dependent patients aged 65 years or older compared with oral bisphosphonates. Given the complexity of diagnosing the underlying bone pathophysiology in dialysis-dependent patients, the high risk posed by denosumab in this population, and the complex strategies required to monitor and treat severe hypocalcemia, denosumab should be administered after careful patient selection and with plans for frequent monitoring.

Limited health literacy and adverse outcomes among kidney transplant candidates

More than one-third of US adults have limited health literacy, putting them at risk of adverse clinical outcomes. We evaluated the prevalence of limited health literacy among 1578 adult kidney transplant (KT) candidates (May 2014-November 2017) and examined its association with listing for transplant and waitlist mortality in this pilot study. Limited health literacy was assessed at KT evaluation by using a standard cutoff score ≤5 on the Brief Health Literacy Screen (score range 0-12, lower scores indicate worse health literacy). We used logistic regression and adjusted Cox proportional hazards models to identify risk factors for limited health literacy and to quantify its association with listing and waitlist mortality. We found that 8.9% of candidates had limited health literacy; risk factors included less than college education (adjusted odds ratio [aOR] = 2.87, 95% confidence interval [CI]:1.86-4.43), frailty (aOR = 1.85, 95% CI:1.22-2.80), comorbidity (Charlson comorbidity index [1-point increase] aOR = 1.12, 95% CI: 1.04-1.20), and cognitive impairment (aOR = 3.45, 95% CI: 2.20-5.41) after adjusting for age, sex, race, and income. Candidates with limited health literacy had a 30% (adjusted hazard ratio = 0.70, 95% CI: 0.54-0.91) decreased likelihood of listing and a 2.42-fold (95% CI: 1.16- to 5.05-fold) increased risk of waitlist mortality. Limited health literacy may be a salient mechanism in access to KT; programs to aid candidates with limited health literacy may improve outcomes and reduce disparities.

Development and optimization of a doxorubicin loaded poly(lactic acid) contrast agent for ultrasound directed drug delivery

An echogenic, intravenous drug delivery platform is proposed in which an encapsulated chemotherapeutic can travel to a desired location and drug delivery can be triggered using external, focused ultrasound at the area of interest. Three methods of loading poly(lactic acid) (PLA) shelled ultrasound contrast agents (UCA) with doxorubicin are presented. Effects on encapsulation efficiency, in vitro enhancement, stability, particle size, morphology and release during UCA rupture are compared by loading method and drug concentration. An agent containing doxorubicin within the shell was selected as an ideal candidate for future hepatocellular carcinoma studies. The agent achieved a maximal drug load of 6.2 mg Dox/g PLA with an encapsulation efficiency of 20.5%, showed a smooth surface morphology and tight size distribution (poly dispersity index=0.309) with a peak size of 1865 nm. Acoustically, the agent provided 19 dB of enhancement in vitro at a dosage of 10 microg/ml, with a half life of over 15 min. In vivo, the agent provided ultrasound enhancement of 13.4+/-1.6 dB within the ascending aorta of New Zealand rabbits at a dose of 0.15 ml/kg. While the drug-incorporated agent is thought to be well suited for future drug delivery experiments, this study has shown that agent properties can be tailored for specific applications based on choice of drug loading method.