Propensity score matching and persistence correction to reduce bias in comparative effectiveness: the effect of cinacalcet use on all-cause mortality

Concerns About the Generalizability Associated With a South African Randomized Controlled Trial on Prenatal Mothers

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Concerns on Generalizability

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Cinacalcet Treatment Significantly Improves All-Cause and Cardiovascular Survival in Dialysis Patients: Results from a Meta-Analysis

OBJECTIVE

To assess the long-term effects including all-cause mortality, cardiovascular mortality, and fracture incidence, of cinacalcet on secondary hyperparathyroidism (SHPT) in patients on dialysis.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched from their inception to October 2018. Randomized controlled trials (RCTs) and cohort design prospective observational studies assessing cinacalcet for the treatment of SHPT in dialysis patients were included. Data extraction was independently completed by 2 authors who determined the methodological quality of the studies and extracted data in duplicate. Study-specific risk estimates were tested by using a fixed effects model.

RESULTS

A total of 14 articles with 38,219 participants were included, of which 10 RCTs with 7,471 participants and 4 prospective observational studies with 30,748 participants fulfilled the eligibility criteria. Compared with no cinacalcet, cinacalcet administration reduced all-cause mortality (relative risk [RR] 0.91, 95% CI 0.89-0.94, p < 0.001) and cardiovascular mortality (RR 0.92, 95% CI 0.89-0.95, p < 0.001), but it did not significantly reduce the incidence of fractures (RR 0.93, 95% CI 0.87-1.00, p = 0.05).

CONCLUSIONS

The results of this meta-analysis indicated that the treatment of SHPT with cinacalcet may in fact reduce all-cause mortality and cardiovascular mortality among patients receiving maintenance dialysis.

Industrial air pollution and mortality in the Taranto area, Southern Italy: A difference-in-differences approach

BACKGROUND

A large steel plant close to the urban area of Taranto (Italy) has been operating since the sixties. Several studies conducted in the past reported an excess of mortality and morbidity from various diseases at the town level, possibly due to air pollution from the plant. However, the relationship between air pollutants emitted from the industry and adverse health outcomes has been controversial. We applied a variant of the "difference-in-differences" (DID) approach to examine the relationship between temporal changes in exposure to industrial PM₁₀ from the plant and changes in cause-specific mortality rates at area unit level.

METHODS

We examined a dynamic cohort of all subjects (321,356 individuals) resident in the Taranto area in 1998-2010 and followed them up for mortality till 2014. In this work, we included only deaths occurring on 2008-2014. We observed a total of 15,303 natural deaths in the cohort and age-specific annual death rates were computed for each area unit (11 areas in total). PM₁₀ and NO₂ concentrations measured at air quality monitoring stations and the results of a dispersion model were used to estimate annual average population weighted exposures to PM₁₀ of industrial origin for each year, area unit and age class. Changes in exposures and in mortality were analyzed using Poisson regression.

RESULTS

We estimated an increased risk in natural mortality (1.86%, 95% confidence interval [CI]: -0.06, 3.83%) per 1 μg/m³ annual change of industrial PM₁₀, mainly driven by respiratory causes (8.74%, 95% CI: 1.50, 16.51%). The associations were statistically significant only in the elderly (65+ years).

CONCLUSIONS

The DID approach is intuitively simple and reduces confounding by design. Under the multiple assumptions of this approach, the study indicates an effect of industrial PM₁₀ on natural mortality, especially in the elderly population.

Effects of calcimimetics on long-term outcomes in dialysis patients: literature review and Bayesian meta-analysis

Aim: Randomized controlled trials (RCTs) with clinical outcomes are considered the gold standard for regulatory approval. However, by design they are only able to answer a small number of clinical questions. Other high-quality studies are required for clinical decision-making. The EVOLVE was the largest RCT, evaluating the effects of cinacalcet on clinical outcomes among adult patients receiving maintenance dialysis suffering from secondary hyperparathyroidism. While the EVOLVE trial did not reach its primary end point, imbalance in subjects’ age at randomization and discontinuation rates are two of the reasons that the lack of mortality benefit is in question. We undertook a systematic literature review and Bayesian meta-analysis combining randomized and observational studies on the estimated effects of the oral calcimimetic cinacalcet on clinical outcomes including all-cause mortality, cardiovascular-related mortality, hospitalization for cardiovascular events, fracture and parathyroidectomy among patients on maintenance dialysis. Methods: Data sources included MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials databases. RCTs and observational studies were included. Data extraction was completed by two authors independently and in duplicate determined the methodological quality of the studies and extracted data. Results: Of 564 unique citations identified, 16 studies were included: six observational studies and ten RCTs. Four high-quality studies (two observational and two RCTs) were deemed suitable for meta-analysis. Results indicated a statistically significant reduction in the risk of death associated with cinacalcet (hazard ratio: 0.83; 95% credible interval: 0.78–0.89).Conclusion: The results of this meta-analysis indicate that treatment of secondary hyperparathyroidism with calcimimetic therapy may in fact reduce mortality among patients receiving maintenance dialysis. This finding provides justification for a well-designed and adequately powered randomized trial to definitively address the question.

Cost-consequence analysis of salvianolate injection for the treatment of coronary heart disease

Background

Complicated with the impact of aging population and urbanization, coronary heart disease (CHD) incurs more and more disease burdens in China. Salvianolate injection is a Chinese patent drug widely used for treating CHD in China. A series of studies have verified the efficacy of salvianolate injection , but the high drug cost has raised concerns. It is, therefore, important to conduct cost-consequence analysis to demonstrate whether salvianolate injection is associated with outcome improvement and cost containment. The aim of this study was to retrospectively evaluate the cost-consequence of salvianolate injection for the treatment of coronary heart disease by combining salvianolate injection with conventional treatment from a societal perspective.

Methods

We retrospectively studied hospitalized patients with CHD from August 2011 to December 2015 by using electronic medical record database. Patients who received salvianolate injection combined with conventional treatment were selected as exposed group, while those who received conventional treatment alone were selected as unexposed group. Propensity score matching (PSM) analysis was used to balance the characteristics of patients. After PSM, we evaluated hospital stay, total nitrates dosage, total medical costs, and subcategories costs. Patients with chronic ischemic heart disease were analyzed as a highly selected subcohort.

Results

For the overall group, hospital stay was significantly decreased by 2.9 days (P < 0.05) and total nitrates dosage was significantly decreased by 172.4 mg (P < 0.05) in exposed group; cost savings of pharmacy cost, examination cost, laboratory cost, operation cost and treatment was observed as significant (at P < 0.05); and the additional expenditure of Chinese patent drug (1174.9 CNY) was less than the saving of total medical costs (2636.4 CNY). For chronic ischemic heart disease subcohort, compared with unexposed group, significant decreases were also found in hospital stay and total nitrates dosage (P < 0.05); cost savings were significant (P < 0.05) for exposed group in terms of total medical costs (4339.5 CNY) and subcategories costs (including pharmacy cost, examination cost, operation cost and treatment cost); and the additional expenditure of Chinese patent drug (1189.3 CNY) was less than the saving of total medical costs.

Conclusion

Compared with conventional treatment for the treatment of CHD, combination of salvianolate injection and conventional treatment was associated with a reduction in hospital stay and total nitrates dosage. The acquisition cost of Chinese patent drug (including salvianolate injection) was offset by a higher reduction in total medical costs, especially for chronic ischemic heart disease.

Electronic supplementary material

The online version of this article (10.1186/s13020-018-0185-x) contains supplementary material, which is available to authorized users.

Old and new calcimimetics for treatment of secondary hyperparathyroidism: impact on biochemical and relevant clinical outcomes

Secondary hyperparathyroidism (SHPT) is associated with increased bone turnover, risk of fractures, vascular calcifications, and cardiovascular and all-cause mortality. The classical treatment for SHPT includes active vitamin D compounds and phosphate binders. However, achieving the optimal laboratory targets is often difficult because vitamin D sterols suppress parathyroid hormone (PTH) secretion, while also promoting calcium and phosphate intestinal absorption. Calcimimetics increase the sensitivity of the calcium-sensing receptor, so that even with lower levels of extracellular calcium a signal can still exist, leading to a decrease of the set-point for systemic calcium homeostasis. This enables a decrease in plasma PTH levels and, consequently, of calcium levels. Cinacalcet was the first calcimimetic to be approved for clinical use. More than 10 years since its approval, cinacalcet has been demonstrated to effectively reduce PTH and improve biochemical control of mineral and bone disorders in chronic kidney patients. Three randomized controlled trials have analysed the effects of treatment with cinacalcet on hard clinical outcomes such as vascular calcification, bone histology and cardiovascular mortality and morbidity. However, a final conclusion on the effect of cinacalcet on hard outcomes remains elusive. Etelcalcetide is a new second-generation calcimimetic with a pharmacokinetic profile that allows thrice-weekly dosing at the time of haemodialysis. It was recently approved in Europe, and is regarded as a second opportunity to improve outcomes by optimizing treatment for SHPT. In this review, we summarize the impact of cinacalcet with regard to biochemical and clinical outcomes. We also discuss the possible implications of the new calcimimetic etelcalcetide in the quest to improve outcomes.

The association between cinacalcet use and missed in-center hemodialysis treatment rate

PURPOSE

Missed in-center hemodialysis treatments (MHT) are a general indicator of health status in hemodialysis patients. This analysis was conducted to estimate the association between cinacalcet use and MHT rate.

METHODS

We studied patients receiving hemodialysis and prescription benefits services from a large dialysis organization. Incident cinacalcet users were propensity score matched to controls on 31 demographic, clinical, and laboratory variables. We applied inverse probability (IP) of censoring and crossover weights to account for informative censoring. Weighted negative binomial modeling was used to estimate MHT rates and pooled logistics models were used to estimate the association between cinacalcet use and MHT.

RESULTS

Baseline demographic and clinical variables included serum calcium, phosphorus, parathyroid hormone, and vitamin D use, and were balanced between 15,474 new cinacalcet users and 15,474 matched controls. In an analysis based on intention-to-treat principles, 40.8% of cinacalcet users and 46.5% of nonusers were censored. MHT rate was 13% lower among cinacalcet initiators versus controls: IP of censoring weighted incidence rate ratio was 0.87 (95% confidence interval [CI]: 0.84-0.90 p < 0.001). In analyses based on as-treated principles, 72.8% and 61.5% of cinacalcet users and nonusers, respectively, crossed over or were censored. MHT rate was 15% lower among cinacalcet initiators versus controls: IP of censoring/crossover weighted incidence rate ratio was 0.85 (95%CI: 0.82-0.87 p < 0.001).

CONCLUSIONS

After controlling for indication and differential censoring, cinacalcet treatment was associated with lower MHT rates, which may reflect better health status. Copyright © 2016 John Wiley & Sons, Ltd.

Propensity score matching and persistence correction to reduce bias in comparative effectiveness: the effect of cinacalcet use on all-cause mortality

Purpose

The generalisability of randomised controlled trials (RCTs) may be limited by restrictive entry criteria or by their experimental nature. Observational research can provide complementary findings but is prone to bias. Employing propensity score matching, to reduce such bias, we compared the real‐life effect of cinacalcet use on all‐cause mortality (ACM) with findings from the Evaluation of Cinacalcet Therapy to Lower Cardiovascular Events (EVOLVE) RCT in chronic haemodialysis patients.

Methods

Incident adult haemodialysis patients receiving cinacalcet, recruited in a prospective observational cohort from 2007–2009 (AROii; n = 10,488), were matched to non‐exposed patients regardless of future exposure status. The effect of treatment crossover was investigated with inverse probability of censoring weighted and lag‐censored analyses. EVOLVE ACM data were analysed largely as described for the primary composite endpoint.

Results

AROii patients receiving cinacalcet (n = 532) were matched to 1790 non‐exposed patients. The treatment effect of cinacalcet on ACM in the main AROii analysis (hazard ratio 1.03 [95% confidence interval (CI) 0.78–1.35]) was closer to the null than for the Intention to Treat (ITT) analysis of EVOLVE (0.94 [95%CI 0.85–1.04]). Adjusting for non‐persistence by 0‐ and 6‐month lag‐censoring and by inverse probability of censoring weight, the hazard ratios in AROii (0.76 [95%CI 0.51–1.15], 0.84 [95%CI 0.60–1.18] and 0.79 [95%CI 0.56–1.11], respectively) were comparable with those of EVOLVE (0.82 [95%CI 0.67–1.01], 0.83 [95%CI 0.73–0.96] and 0.87 [95%CI 0.71–1.06], respectively).

Conclusions

Correcting for treatment crossover, we observed results in the ‘real‐life’ setting of the AROii observational cohort that closely mirrored the results of the EVOLVE RCT. Persistence‐corrected analyses revealed a trend towards reduced ACM in haemodialysis patients receiving cinacalcet therapy. © 2015 The Authors. Pharmacoepidemiology and Drug Safety Published by John Wiley & Sons Ltd.