Emulating a trial of joint dynamic strategies: An application to monitoring and treatment of HIV-positive individuals

Decisions about when to start or switch a therapy often depend on the frequency with which individuals are monitored or tested. For example, the optimal time to switch antiretroviral therapy depends on the frequency with which HIV-positive individuals have HIV RNA measured. This paper describes an approach to use observational data for the comparison of joint monitoring and treatment strategies and applies the method to a clinically relevant question in HIV research: when can monitoring frequency be decreased and when should individuals switch from a first-line treatment regimen to a new regimen? We outline the target trial that would compare the dynamic strategies of interest and then describe how to emulate it using data from HIV-positive individuals included in the HIV-CAUSAL Collaboration and the Centers for AIDS Research Network of Integrated Clinical Systems. When, as in our example, few individuals follow the dynamic strategies of interest over long periods of follow-up, we describe how to leverage an additional assumption: no direct effect of monitoring on the outcome of interest. We compare our results with and without the “no direct effect” assumption. We found little differences on survival and AIDS-free survival between strategies where monitoring frequency was decreased at a CD4 threshold of 350 cells/μl compared with 500 cells/μl and where treatment was switched at an HIV-RNA threshold of 1000 copies/ml compared with 200 copies/ml. The “no direct effect” assumption resulted in efficiency improvements for the risk difference estimates ranging from an 7- to 53-fold increase in the effective sample size.     

Ultimate journey of the terminally ill: Ways and pathways of hope

ObjectiveTo better understand the role of hope among terminally ill cancer patients.DesignQualitative analysis.SettingA tertiary specialized cancer centre in Canada.ParticipantsCancer patients in palliative care with an estimated remaining life expectancy of 12 months or less (N = 12) and their loved ones (N = 12) and treating physicians (N = 12).MethodsEach patient underwent up to 3 interviews and identified a loved one who participated in 1 interview. Treating physicians were also interviewed. All interviews were fully transcribed and analyzed by at least 2 investigators. Interviews were collected until saturation occurred.ConclusionApproaches aimed at sustaining hope need to reflect that patients’ reactions might fluctuate between despair and a form of acceptance that leads to a certain serenity. Clinicians need to maintain some degree of hope while remaining as realistic as possible. The findings also raise questions about how hope influences patients’ perceptions and acceptance of their treatments.     

Activity of Isavuconazole and Other Azoles against Candida Clinical Isolates and Yeast Model Systems with Known Azole Resistance Mechanisms

Isavuconazole is a novel, broad-spectrum, antifungal azole. In order to evaluate its interactions with known azole resistance mechanisms, isavuconazole susceptibility among different yeast models and clinical isolates expressing characterized azole resistance mechanisms was tested and compared to those of fluconazole, itraconazole, posaconazole, and voriconazole. Saccharomyces cerevisiae expressing the Candida albicans and C. glabrata ATP binding cassette (ABC) transporters (CDR1, CDR2, and CgCDR1), major facilitator (MDR1), and lanosterol 14-α-sterol-demethylase (ERG11) alleles with mutations were used. In addition, pairs of C. albicans and C. glabrata strains from matched clinical isolates with known azole resistance mechanisms were investigated. The expression of ABC transporters increased all azole MICs, suggesting that all azoles tested were substrates of ABC transporters. The expression of MDR1 did not increase posaconazole, itraconazole, and isavuconazole MICs. Relative increases of azole MICs (from 4- to 32-fold) were observed for fluconazole, voriconazole, and isavuconazole when at least two mutations were present in the same ERG11 allele. Upon MIC testing of azoles with clinical C. albicans and C. glabrata isolates with known resistance mechanisms, the MIC₉₀s of C. albicans for fluconazole, voriconazole, itraconazole, posaconazole, and isavuconazole were 128, 2, 1, 0.5, and 2 μg/ml, respectively, while in C. glabrata they were 128, 2, 4, 4, and 16 μg/ml, respectively. In conclusion, the effects of azole resistance mechanisms on isavuconazole did not differ significantly from those of other azoles. Resistance mechanisms in yeasts involving ABC transporters and ERG11 decreased the activity of isavuconazole, while MDR1 had limited effect.     

Lithium poisoning in the intensive care unit: predictive factors of severity and indications for extracorporeal toxin removal to improve outcome

Context: Lithium is responsible for life-threatening poisoning, not consistently improved by extracorporeal toxin removal (ECTR).

Objective: Our aim was to identify predictive factors on admission of poisoning severity and based on an evaluation of practice, report indications for ECTR susceptible to improve outcome

Methods: We performed a retrospective cohort study including all lithium-poisoned patients admitted to the ICU in a university hospital. The usual clinical, biological and toxicological variables were collected. Poisoning severity was defined by seizures, catecholamine infusion, mechanical ventilation >48?h and/or fatality. Univariate followed by multiple logistic regression analyses were performed to identify prognosticators of poisoning severity and ECTR use.

Results: From 1992 to 2013, 128 lithium-poisoned patients including acutely (10%), acute-on-chronically (63%) and chronically poisoned patients (27%) were included. The presumed ingested dose of lithium was 17.0?g [8.0–24.5] (median [25th–75th percentiles]). Serum lithium concentrations were 2.6?mmol/l [1.5–4.6], 2.8?mmol/l [1.8–4.5] and 2.8?mmol/l [2.1–3.0] on admission, peaking at 3.6?mmol/l [2.6; 6.2], 4.3?mmol/l [2.4; 6.2] and 2.8?mmol/l [2.1; 3.1] in the three groups, respectively. Severe poisoning occurred in 48 patients (38%) including four fatalities. Using the regression analysis, predictive factors of poisoning severity were Glasgow coma score ≤10 (Odds ratio (OR), 11.1; 95% confidence interval (CI), [4.1–33.3], p?p?=?0.005). Ninety-eight patients (77%) developed acute kidney injury according to KDIGO criteria and 22 (17%) were treated with ECTR. Peak lithium concentration ≥5.2?mmol/l (OR, 22.4; CI, [6.4–96.4]; p?p?=?0.01) were associated with ECTR use. Only 21/46 patients who presented one of these two criteria were actually treated with ECTR. More significant neurological impairment persisted on discharge in patients not treated with ECTR (p?=?0.0007) despite not significantly shorter length of ICU stay.

Conclusions: Lithium poisoning is responsible for severe impairments but rare fatalities. Severity can be predicted on admission using Glasgow coma score and lithium concentration. Our results suggest that ECTR could be indicated if serum lithium ≥5.2?mmol/l or creatinine ≥200?μmol/l.     

Activation of recombinant alphaIIbbeta3 expressed in Chinese hamster ovary cells exposes different binding sites for fibrinogen or von Willebrand factor: evidence using monoclonal antibodies to alphaIIbbeta3

We have investigated the interaction of von Willebrand factor (VWF) and fibrinogen (Fg) with recombinant integrin alphaIIbbeta3 expressed in Chinese hamster ovary (CHO) cells either in its native conformation or following partial reduction by dithiothreitol (DTT). We found that DTT-treated cells aggregated in the presence of soluble VWF as well as Fg, whereas non-treated cells did not. Furthermore, we demonstrated that DTT was required to specifically induce alphaIIbbeta3-dependent cell adhesion to immobilized VWF, while Fg-dependent cell adhesion occurred independently of the activation state of alphaIIbbeta3. By comparing the effects of two potent platelet alphaIIbbeta3 inhibitors, monoclonal antibodies (mAbs) AP2 and 10E5, we highlighted the different blocking properties of these mAbs on VWF or Fg binding to activated alphaIIbbeta3. In particular, AP2 prevented VWF-dependent but not Fg-dependent CHO cell aggregation. Furthermore, AP2 inhibited cell adhesion to VWF, but had no effect on adhesion to Fg. In contrast to this distinct effect of AP2 towards these two ligands, mAb 10E5 inhibited activated alphaIIbbeta3-dependent aggregation completely and adhesion partially, whether in the presence of Fg or VWF. These data provide evidence that interaction of VWF and Fg with DTT-activated alphaIIbbeta3 relies on distinct contact sites exposed on the activated receptor that can be selectively blocked by monoclonal antibodies.