scholarly journals Prior event rate ratio adjustment for hidden confounding in observational studies of treatment effectiveness: a pairwise Cox likelihood approach

2016 ◽  
Vol 35 (28) ◽  
pp. 5149-5169 ◽  
Author(s):  
Nan Xuan Lin ◽  
William Edward Henley
2020 ◽  
Vol 190 (1) ◽  
pp. 142-149
Author(s):  
Robertus van Aalst ◽  
Edward Thommes ◽  
Maarten Postma ◽  
Ayman Chit ◽  
Issa J Dahabreh

Abstract A growing number of studies use data before and after treatment initiation in groups exposed to different treatment strategies to estimate “causal effects” using a ratio measure called the prior event rate ratio (PERR). Here, we offer a causal interpretation for PERR and its additive scale analog, the prior event rate difference (PERD). We show that causal interpretation of these measures requires untestable rate-change assumptions about the relationship between 1) the change of the counterfactual rate before and after treatment initiation in the treated group under hypothetical intervention to implement the control strategy; and 2) the change of the factual rate before and after treatment initiation in the control group. The rate-change assumption is on the multiplicative scale for PERR but on the additive scale for PERD; the 2 assumptions hold simultaneously under testable, but unlikely, conditions. Even if investigators can pick the most appropriate scale, the relevant rate-change assumption might not hold exactly, so we describe sensitivity analysis methods to examine how assumption violations of different magnitudes would affect study results. We illustrate the methods using data from a published study of proton pump inhibitors and pneumonia.


2020 ◽  
Vol 122 ◽  
pp. 78-86
Author(s):  
Lauren R. Rodgers ◽  
John M. Dennis ◽  
Beverley M. Shields ◽  
Luke Mounce ◽  
Ian Fisher ◽  
...  

2014 ◽  
Vol 24 (5) ◽  
pp. 468-477 ◽  
Author(s):  
Md Jamal Uddin ◽  
Rolf H. H. Groenwold ◽  
Tjeerd P. van Staa ◽  
Anthonius de Boer ◽  
Svetlana V. Belitser ◽  
...  

2019 ◽  
Vol 39 (5) ◽  
pp. 639-659 ◽  
Author(s):  
Edward W. Thommes ◽  
Salaheddin M. Mahmud ◽  
Yinong Young‐Xu ◽  
Julia Thornton Snider ◽  
Robertus Aalst ◽  
...  

2020 ◽  
pp. 2002795
Author(s):  
Fergus Hamilton ◽  
David Arnold ◽  
William Henley ◽  
Rupert A. Payne

BackgroundIschaemic stroke and myocardial infarction (MI) are common after pneumonia and are associated with long-term mortality. Aspirin may attenuate this risk and should be explored as a therapeutic option.MethodsWe extracted all patients with pneumonia, aged over 50, from the Clinical Practice Research Datalink (CPRD), a large UK primary care database, from inception until January 2019. We then performed a prior event rate ratio analysis (PERR) with propensity score matching, an approach that allows for control of measured and unmeasured confounding, with aspirin usage as the exposure, and ischaemic events as the outcome. The primary outcome was the combined outcome of ischaemic stroke and myocardial infarction. Secondary outcomes were ischaemic stroke and myocardial infarction individually. Relevant confounders were included in the analysis (smoking, comorbidities, age, gender).Findings48 743 patients were eligible for matching. 8099 of these were aspirin users who were matched to 8099 non-users. Aspirin users had a reduced risk of the primary outcome (adjusted hazard ratio, HR 0.64; 95% confidence interval 0.52–0.79) in the PERR analysis. For both secondary outcomes, aspirin use was also associated with a reduced risk HR 0.46 (0.30–0.72) and HR 0.70 (0.55–0.91) for myocardial infarction and stroke respectively).InterpretationThis study provides supporting evidence that aspirin use is associated with reduced ischaemic events after pneumonia in a primary care setting. This drug may have a future clinical role in preventing this important complication.


2017 ◽  
Vol 10 ◽  
pp. 1178623X1773004 ◽  
Author(s):  
Jan Endrikat ◽  
Nicoletta Anzalone

Gadobutrol is a gadolinium (Gd)-based contrast agent for magnetic resonance imaging (MRI). In India, gadobutrol is approved for MRI of the central nervous system (CNS), liver, kidneys, breast and for MR angiography for patients 2 years and older. The standard dose for all age groups is 0.1 mmol/kg body weight. The safety profile has been demonstrated in 42 clinical phase 2 to 4 studies (>6800 patients), 7 observational studies, and by assessing pharmacovigilance data of 29 million applications. Furthermore, studies in children, adults, and elderly and in patients with impaired liver or kidney function did not show any increased adverse event rate. Diagnostic efficacy was demonstrated in numerous studies and various indications, such as diseases of the CNS, peripheral and supra-aortic vessels, kidneys, liver, and breast.


2020 ◽  
pp. 193229682095766
Author(s):  
Morten Hasselstrøm Jensen ◽  
Peter Vestergaard ◽  
Irl B. Hirsch ◽  
Ole Hejlesen

Aims: Continuous glucose monitoring (CGM) has the potential to promote diabetes self-management at home with a better glycemic control as outcome. Investigation of the effect of CGM has typically been carried out based on randomized controlled trials with prespecified CGM devices on CGM-naïve participants. The aim of this study was to investigate the effect on glycemic control in people using their personal CGM before and during the trial. Materials and Methods: Data from the Onset 5 trial of 472 people with type 1 diabetes using either their personal CGM ( n = 117) or no CGM ( n = 355) and continuous subcutaneous insulin infusion in a 16-week treatment period were extracted. Change from baseline in glycated hemoglobin A1c (HbA1c), number of hypoglycemic episodes, and CGM metrics at the end of treatment were analyzed with analysis of variance repeated-measures models. Results: Use of personal CGM compared with no CGM was associated with a reduction in risk of documented symptomatic hypoglycemia (event rate ratio: 0.82; 95% CI: 0.69-0.97) and asymptomatic hypoglycemia (event rate ratio: 0.72; 95% CI: 0.53-0.97), reduced time spent in hypoglycemia ( P = .0070), and less glycemic variability ( P = .0043) without a statistically significant increase in HbA1c ( P = .2028). Conclusions: Results indicate that use of personal CGM compared with no CGM in a population of type 1 diabetes is associated with a safer glycemic control without a statistically significantly deteriorated effect on HbA1c, which adds to the evidence about the real-world use of CGM, where device type is not prespecified, and users are not CGM naïve.


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