The importance and implications of comparator selection in pharmacoepidemiologic research

Bariatric surgery and all-cause mortality: A methodological review of studies using a non-surgical comparator

AIM

Non-randomized studies on bariatric surgery have reported large reductions in mortality within 6-12 months after surgery compared with non-surgical patients. It is unclear whether these findings are the result of bias.

STUDY DESIGN AND SETTING

We searched PubMed to identify all non-randomized studies investigating the effect of bariatric surgery on all-cause mortality compared with non-surgical patients. We assessed these studies for potential confounding and time-related biases. We conducted bias analyses to quantify the effect of these biases.

RESULTS

We identified 21 cohort studies that met our inclusion criteria. Among those, 11 were affected by immortal time bias resulting from the misclassification or exclusion of relevant follow-up time. Five studies were subject to potential confounding bias because of a lack of adjustment for body mass index (BMI). All studies used an inadequate comparator group that lacked indications for bariatric surgery. Bias analyses to correct for potential confounding from BMI shifted the effect estimates towards the null [reported hazard ratio (HR): 0.78 vs. bias-adjusted HR: 0.92]. Bias analyses to correct for the presence of immortal time also shifted the effect estimates towards the null (adjustment for 2-year wait time: reported HR: 0.57 vs. bias-adjusted HR: 0.81).

CONCLUSION

Several important sources of bias were identified in non-randomized studies of the effectiveness of bariatric surgery versus non-surgical comparators on mortality. Future studies should ensure that confounding by BMI is accounted for, considering the choice of the comparator group, and that the design or analysis avoids immortal time bias from the misclassification or exclusion.

Association between sodium-glucose cotransporter-2 inhibitors and arrhythmic outcomes in patients with diabetes and pre-existing atrial fibrillation

AIMS

Prior studies suggest that sodium-glucose cotransporter-2 inhibitors (SGLT2is) may decrease the incidence of atrial fibrillation (AF). However, it is unknown whether SGLT2i can attenuate the disease course of AF among patients with pre-existing AF and Type II diabetes mellitus (DM). In this study, our objective was to examine the association between SGLT2i prescription and arrhythmic outcomes among patients with DM and pre-existing AF.

METHODS AND RESULTS

We conducted a population-based cohort study of adults with DM and AF between 2014 and 2019. Using a prevalent new-user design, individuals prescribed SGLT2i were matched 1:1 to those prescribed dipeptidyl peptidase-4 inhibitors (DPP4is) based on time-conditional propensity scores. The primary endpoint was a composite of AF-related healthcare utilization (i.e. hospitalization, emergency department visits, electrical cardioversion, or catheter ablation). Secondary outcome measures included all-cause mortality, heart failure (HF) hospitalization, and ischaemic stroke or transient ischaemic attack (TIA). Cox proportional hazard models were used to examine the association of SGLT2i with the study endpoint. Among 2242 patients with DM and AF followed for an average of 3.0 years, the primary endpoint occurred in 8.7% (n = 97) of patients in the SGLT2i group vs. 10.0% (n = 112) of patients in the DPP4i group [adjusted hazard ratio 0.73 (95% confidence interval 0.55-0.96; P = 0.03)]. Sodium-glucose cotransporter-2 inhibitors were associated with significant reductions in all-cause mortality and HF hospitalization, but there was no difference in the risk of ischaemic stroke/TIA.

CONCLUSION

Among patients with DM and pre-existing AF, SGLT2is are associated with decreased AF-related health resource utilization and improved arrhythmic outcomes compared with DPP4is.

Framework for the Use of External Controls to Evaluate Treatment Outcomes in Precision Oncology Trials

Advances in genomics have enabled anticancer therapies to be tailored to target specific genomic alterations. Single-arm trials (SATs), including those incorporated within umbrella, basket, and platform trials, are widely adopted when it is not feasible to conduct randomized controlled trials in rare biomarker-defined subpopulations. External controls (ECs), defined as control arm data derived outside the clinical trial, have gained renewed interest as a strategy to supplement evidence generated from SATs to allow comparative analysis. There are increasing examples demonstrating the application of EC in precision oncology trials. The prospective application of EC in conducting comparative studies is associated with distinct methodological challenges, the specific considerations for EC use in biomarker-defined subpopulations have not been adequately discussed, and a formal framework is yet to be established. In this review, we present a framework for conducting a prospective comparative analysis using EC. Key steps are (1) defining the purpose of using EC to address the study question, (2) determining if the external data are fit for purpose, (3) developing a transparent study protocol and a statistical analysis plan, and (iv) interpreting results and drawing conclusions on the basis of a prespecified hypothesis. We specify the considerations required for the biomarker-defined subpopulations, which include (1) specifying the comparator and biomarker status of the comparator group, (2) defining lines of treatment, (3) assessment of the biomarker testing panels used, and (4) assessment of cohort stratification in tumor-agnostic studies. We further discuss novel clinical trial designs and statistical techniques leveraging EC to propose future directions to advance evidence generation and facilitate drug development in precision oncology.

Comparative Safety and Attributable Healthcare Expenditures Following Inappropriate Versus Appropriate Outpatient Antibiotic Prescriptions Among Adults With Upper Respiratory Infections

BACKGROUND

Little is known about the clinical and financial consequences of inappropriate antibiotics. We aimed to estimate the comparative risk of adverse drug events and attributable healthcare expenditures associated with inappropriate versus appropriate antibiotic prescriptions for common respiratory infections.

METHODS

We established a cohort of adults aged 18 to 64 years with an outpatient diagnosis of a bacterial (pharyngitis, sinusitis) or viral respiratory infection (influenza, viral upper respiratory infection, nonsuppurative otitis media, bronchitis) from 1 April 2016 to 30 September 2018 using Merative MarketScan Commercial Database. The exposure was an inappropriate versus appropriate oral antibiotic (ie, non-guideline-recommended vs guideline-recommended antibiotic for bacterial infections; any vs no antibiotic for viral infections). Propensity score-weighted Cox proportional hazards models were used to estimate the association between inappropriate antibiotics and adverse drug events. Two-part models were used to calculate 30-day all-cause attributable healthcare expenditures by infection type.

RESULTS

Among 3 294 598 eligible adults, 43% to 56% received inappropriate antibiotics for bacterial and 7% to 66% for viral infections. Inappropriate antibiotics were associated with increased risk of several adverse drug events, including Clostridioides difficile infection and nausea/vomiting/abdominal pain (hazard ratio, 2.90; 95% confidence interval, 1.31-6.41 and hazard ratio, 1.10; 95% confidence interval, 1.03-1.18, respectively, for pharyngitis). Thirty-day attributable healthcare expenditures were higher among adults who received inappropriate antibiotics for bacterial infections ($18-$67) and variable (-$53 to $49) for viral infections.

CONCLUSIONS

Inappropriate antibiotic prescriptions for respiratory infections were associated with increased risks of patient harm and higher healthcare expenditures, justifying a further call to action to implement outpatient antibiotic stewardship programs.

A Cross-Sectional Study of Tampering in Xtampza ER, an Abuse-Deterrent Formulation of an Extended-Release Opioid, in a Treatment Center Population

BACKGROUND AND OBJECTIVE

While the current landscape of opioid use disorder (OUD) is complicated by the increase in use of non-prescription opioids, prescription opioids continue to be frequently used in non-medical ways. In response to this abuse, pharmaceutical companies have developed abuse deterrent formulations (ADFs) for extended-release (ER) opioids. To test the effectiveness of Xtampza ER ADF (oxycodone myristate) at reducing tampering, its rate of tampering in a treatment-center population was compared to immediate release (IR) single entity (SE) oxycodone, other ER oxycodone opioids, and ER oxymorphone.

METHODS

Data were collected between the third quarter of 2018 and the third quarter of 2021 from individuals entering nationally distributed opioid treatment programs. To determine odds of tampering with Xtampza ER compared to each comparator, a logistic model was fit with a random intercept allowing for multiple drugs in each subject. Within-subject correlation was assumed to have a compound symmetric relationship.

RESULTS

Overlap among the categories of drug tampering was high. Logistic regression analyses found that oxycodone myristate had lower odds of tampering when compared to both IR SE oxycodone (OR = 0.23 [95% CI 0.11, 0.50], p = 0.0002) and ER oxymorphone (OR = 0.30 [95% CI 0.14, 0.67], p = 0.0038). Oxycodone myristate was not significantly different from other ER oxycodone opioids (OR = 0.5 [95% CI 0.24, 1.03], p = 0.0612). These findings did not change when the estimates were adjusted for age and sex.

CONCLUSIONS

Drugs employing ADF technology may reduce the likelihood of tampering when compared to non-ADF formulations in a treatment-center population, which represents an opportunity for intervention in OUD among those still requiring pain management.

Noninterventional studies in the COVID-19 era: methodological considerations for study design and analysis

The global COVID-19 pandemic has generated enormous morbidity and mortality, as well as large health system disruptions including changes in use of prescription medications, outpatient encounters, emergency department admissions, and hospitalizations. These pandemic-related disruptions are reflected in real-world data derived from electronic medical records, administrative claims, disease or medication registries, and mobile devices. We discuss how pandemic-related disruptions in healthcare utilization may impact the conduct of noninterventional studies designed to characterize the utilization and estimate the effects of medical interventions on health-related outcomes. Using hypothetical studies, we highlight consequences that the pandemic may have on study design elements including participant selection and ascertainment of exposures, outcomes, and covariates. We discuss the implications of these pandemic-related disruptions on possible threats to external validity (participant selection) and internal validity (for example, confounding, selection bias, missing data bias). These concerns may be amplified in populations disproportionately impacted by COVID-19, such as racial/ethnic minorities, rural residents, or people experiencing poverty. We propose a general framework for researchers to carefully consider during the design and analysis of noninterventional studies that use real-world data from the COVID-19 era.

ISPE-Endorsed Guidance in Using Electronic Health Records for Comparative Effectiveness Research in COVID-19: Opportunities and Trade-Offs

As the scientific research community along with healthcare professionals and decision makers around the world fight tirelessly against the coronavirus disease 2019 (COVID-19) pandemic, the need for comparative effectiveness research (CER) on preventive and therapeutic interventions for COVID-19 is immense. Randomized controlled trials markedly under-represent the frail and complex patients seen in routine care, and they do not typically have data on long-term treatment effects. The increasing availability of electronic health records (EHRs) for clinical research offers the opportunity to generate timely real-world evidence reflective of routine care for optimal management of COVID-19. However, there are many potential threats to the validity of CER based on EHR data that are not originally generated for research purposes. To ensure unbiased and robust results, we need high-quality healthcare databases, rigorous study designs, and proper implementation of appropriate statistical methods. We aimed to describe opportunities and challenges in EHR-based CER for COVID-19-related questions and to introduce best practices in pharmacoepidemiology to minimize potential biases. We structured our discussion into the following topics: (1) study population identification based on exposure status; (2) ascertainment of outcomes; (3) common biases and potential solutions; and (iv) data operational challenges specific to COVID-19 CER using EHRs. We provide structured guidance for the proper conduct and appraisal of drug and vaccine effectiveness and safety research using EHR data for the pandemic. This paper is endorsed by the International Society for Pharmacoepidemiology (ISPE).

Metformin is Associated with Reduced COVID-19 Severity in Patients with Prediabetes

Background

With the continuing COVID-19 pandemic, identifying medications that improve COVID-19 outcomes is crucial. Studies suggest that use of metformin, an oral antihyperglycemic, is associated with reduced COVID-19 severity in individuals with diabetes compared to other antihyperglycemic medications. Some patients without diabetes, including those with polycystic ovary syndrome (PCOS) and prediabetes, are prescribed metformin for off-label use, which provides an opportunity to further investigate the effect of metformin on COVID-19.

Participants

In this observational, retrospective analysis, we leveraged the harmonized electronic health record data from 53 hospitals to construct cohorts of COVID-19 positive, metformin users without diabetes and propensity-weighted control users of levothyroxine (a medication for hypothyroidism that is not known to affect COVID-19 outcome) who had either PCOS (n = 282) or prediabetes (n = 3136). The primary outcome of interest was COVID-19 severity, which was classified as: mild, mild ED (emergency department), moderate, severe, or mortality/hospice.

Results

In the prediabetes cohort, metformin use was associated with a lower rate of COVID-19 with severity of mild ED or worse (OR: 0.630, 95% CI 0.450 - 0.882, p < 0.05) and a lower rate of COVID-19 with severity of moderate or worse (OR: 0.490, 95% CI 0.336 - 0.715, p < 0.001). In patients with PCOS, we found no significant association between metformin use and COVID-19 severity, although the number of patients was relatively small.

Conclusions

Metformin was associated with less severe COVID-19 in patients with prediabetes, as seen in previous studies of patients with diabetes. This is an important finding, since prediabetes affects between 19 and 38% of the US population, and COVID-19 is an ongoing public health emergency. Further observational and prospective studies will clarify the relationship between metformin and COVID-19 severity in patients with prediabetes, and whether metformin usage may reduce COVID-19 severity.

Association of Inappropriate Outpatient Pediatric Antibiotic Prescriptions With Adverse Drug Events and Health Care Expenditures

IMPORTANCE

Nonguideline antibiotic prescribing for the treatment of pediatric infections is common, but the consequences of inappropriate antibiotics are not well described.

OBJECTIVE

To evaluate the comparative safety and health care expenditures of inappropriate vs appropriate oral antibiotic prescriptions for common outpatient pediatric infections.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included children aged 6 months to 17 years diagnosed with a bacterial infection (suppurative otitis media [OM], pharyngitis, sinusitis) or viral infection (influenza, viral upper respiratory infection [URI], bronchiolitis, bronchitis, nonsuppurative OM) as an outpatient from April 1, 2016, to September 30, 2018, in the IBM MarketScan Commercial Database. Data were analyzed from August to November 2021.

EXPOSURES

Inappropriate (ie, non-guideline-recommended) vs appropriate (ie, guideline-recommended) oral antibiotic agents dispensed from an outpatient pharmacy on the date of infection.

MAIN OUTCOMES AND MEASURES

Propensity score-weighted Cox proportional hazards models were used to estimate hazards ratios (HRs) and 95% CIs for the association between inappropriate antibiotic prescriptions and adverse drug events. Two-part models were used to calculate 30-day all-cause attributable health care expenditures by infection type. National-level annual attributable expenditures were calculated by scaling attributable expenditures in the study cohort to the national employer-sponsored insurance population.

RESULTS

The cohort included 2 804 245 eligible children (52% male; median [IQR] age, 8 [4-12] years). Overall, 31% to 36% received inappropriate antibiotics for bacterial infections and 4% to 70% for viral infections. Inappropriate antibiotics were associated with increased risk of several adverse drug events, including Clostridioides difficile infection and severe allergic reaction among children treated with a nonrecommended antibiotic agent for a bacterial infection (among patients with suppurative OM, C. difficile infection: HR, 6.23; 95% CI, 2.24-17.32; allergic reaction: HR, 4.14; 95% CI, 2.48-6.92). Thirty-day attributable health care expenditures were generally higher among children who received inappropriate antibiotics, ranging from $21 to $56 for bacterial infections and from -$96 to $97 for viral infections. National annual attributable expenditure estimates were highest for suppurative OM ($25.3 million), pharyngitis ($21.3 million), and viral URI ($19.1 million).

CONCLUSIONS AND RELEVANCE

In this cohort study of children with common infections treated in an outpatient setting, inappropriate antibiotic prescriptions were common and associated with increased risks of adverse drug events and higher attributable health care expenditures. These findings highlight the individual- and national-level consequences of inappropriate antibiotic prescribing and further support implementation of outpatient antibiotic stewardship programs.

Core concepts in pharmacoepidemiology: Confounding by indication and the role of active comparators

Confounding by indication poses a significant threat to the validity of nonexperimental studies assessing effectiveness and safety of medical interventions. While no different from other forms of confounding in theory, confounding by indication often requires specific methods to address the bias it creates in addition to common epidemiological adjustment or restriction methods. Clinical indication influencing treatment prescription is patient-specific and complex, making it challenging to measure within nonexperimental research. Restriction of the study population to patients with the indication for treatment would effectively mitigate confounding by indication and bring about comparability between exposure and comparator populations with respect to probability of the exposure. Active comparators are often an effective practical solution to restrict the study population in this manner when indication cannot be measured accurately. This article discusses various forms of confounding by indication, the utility of active comparators for nonexperimental studies of treatment effects, and the active comparator, new user (ACNU) study design to implicitly condition on indication. Considerations for selecting active comparators and conducting an ACNU study design are discussed to enable increased adoption of these methods, improve quality of nonexperimental studies, and ultimately strengthen our evidence base for intended and unintended treatment effects in relevant target populations.

Use of Proton Pump Inhibitors and Risk of Pancreatic Cancer: A Nationwide Case-Control Study Based on the French National Health Data System (SNDS)

BACKGROUND

Only a few studies investigated the association between proton pump inhibitor (PPI) use and pancreatic cancer, with inconsistent results. Moreover, these studies had a number of methodologic limitations. Our objective was to assess this association in a nationwide case-control study.

METHODS

We used the French National Health Data System (SNDS), covering 99% of the French population since 2006. Incident cases of pancreatic cancer, identified between 2014 and 2018, were matched with up to four controls on year of birth, sex, frequency of hospitalization within 8 years prior to index date, and department of residence. Associations between PPIs and pancreatic cancer were estimated using conditional logistic regression models adjusted for sociodemographic characteristics, risk factors of pancreatic cancer (including diabetes mellitus, tobacco-related diseases, and morbid obesity), and other comorbidities.

RESULTS

A total of 23,321 cases of pancreatic cancer (mean age, 69.8 years; 51.7% males) and 75,937 matched controls were included. Overall, 77.8% of cases and 75.5% of controls were PPI ever users. Ever (vs. never) PPI use was associated with an increased risk of pancreatic cancer [adjusted OR (aOR) = 1.05, 95% confidence interval (CI), 1.01-1.09]. A dose-response relationship was observed [1-30 cumulative defined daily dose (cDDD): aOR = 0.92, 95% CI, 0.87-0.97; 31-180 cDDD: aOR = 1.05, 95% CI, 1.00-1.11; 181-1,080 cDDD: aOR = 1.18, 95% CI, 1.12-1.24; >1,080 cDDD: aOR = 1.17, 95% CI, 1.10-1.23].

CONCLUSIONS

On the basis of these findings, a slight increase in the risk of pancreatic cancer associated with high cumulative doses of PPIs cannot be excluded.

IMPACT

Given the overuse of PPIs, efforts should be continued to limit treatments to appropriate indications and durations.

Emulating a target trial of proton pump inhibitors and dementia risk using claims data

BACKGROUND

Understanding the adverse effects of proton pump inhibitors (PPIs) is important due to their widespread use, but the available evidence for an increased dementia risk among patients taking PPIs is inconclusive. The present study aimed to estimate the causal effect of PPIs on the risk of dementia by target trial emulation and time-varying exposure modeling.

METHODS

Using claims data of 2,698,176 insured people of a large German statutory health insurer, we conceptualized a target trial in which individuals aged 40 years and older were classified as PPI initiators or non-initiators between 2008 and 2018, and followed until diagnosis of dementia, death, loss to follow-up or end of study. Incidence of dementia (ICD-10 codes F00, F01, F03, F05.1, G30, G31.0, G31.1, G31.9, and F02.8+G31.82) was defined applying a 1-year lag window. We used weighted Cox models to estimate the effect of PPI initiation vs. non-initiation on dementia risk and weighted pooled logistic regression to estimate the effect of time-varying use vs. non-use.

RESULTS

29,746 PPI initiators (4.4%) and 26,830 non-initiators (1.3%) were diagnosed with dementia. Comparing PPI initiation with no initiation, the hazard ratio (HR) for dementia was 1.54 (95% confidence interval [CI]: 1.51-1.58). The HR for time-dependent PPI use vs. non-use was 1.56 (95% CI: 1.50-1.63). Differentiated subtypes, including unspecified dementia, Alzheimer's disease (AD), and vascular dementia (VaD), showed increased risk by PPI initiation and time-varying PPI use.

CONCLUSIONS

This study suggests that PPI initiation and time-varying PPI use may increase overall dementia risk.

Risk of COPD Exacerbations Associated with Statins versus Fibrates: A New User, Active Comparison, and High-Dimensional Propensity Score Matched Cohort Study

Background

Several observational studies have found that statins may materially decrease the risk of chronic obstructive pulmonary disease (COPD) exacerbations. However, most of these studies used a prevalent user, non-user comparison approach, which may lead to overestimation of the clinical benefits of statins. We aimed to explore the risk of COPD exacerbations associated with statins with a new user, active comparison approach to address potential methodological concerns. We selected fibrates, another class of lipid-lowering agents, as the reference group because no evidence suggests that fibrates have an effect on COPD exacerbations.

Methods

We identified patients with COPD who initiated statins or fibrates from a nationwide Taiwanese database. Patients were followed from cohort entry to the earliest of the following: hospitalization for COPD exacerbations, death, end of the data, or 180 days after cohort entry. Stratified Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of COPD exacerbations comparing statins with fibrates after variable-ratio propensity score (PS) matching and high-dimensional PS (hd-PS) matching, respectively.

Results

We identified a total of 134,909 eligible patients (110,726 initiated statins; 24,183 initiated fibrates); 1979 experienced COPD exacerbations during follow-up. The HRs were 1.10 (95% CI, 0.96 to 1.26) after PS matching and 1.08 (95% CI, 0.94 to 1.24) after hd-PS matching. The results did not differ materially by type of statins and patient characteristic and did not change with longer follow-up durations.

Conclusion

This large-scale, population-based cohort study did not show that use of statins was associated with a reduced risk of acute exacerbations in patients with COPD using state-of-the-art pharmacoepidemiologic approaches. The findings emphasize the importance of applying appropriate methodology in exploring statin effectiveness in real-world settings.

The long-term risk for myocardial infarction or stroke after proton pump inhibitor therapy (2008-2018)

BACKGROUND

Proton pump inhibitors (PPIs) are well tolerated in the short term but have recently been associated with increased long-term cardiovascular risk in observational studies.

AIMS

To evaluate long-term risks of myocardial infarction (MI) and ischaemic stroke (IS) associated with PPI vs H₂ -receptor antagonist (H₂ RA) therapy in adults without pre-existing cardiovascular or cerebrovascular disease METHODS: Using administrative claims data (2008-2018), we emulated a target trial comparing MI and IS risks in new users of PPIs vs H₂ RAs. Treatment was identified using dispensed prescriptions. MI and IS were defined using hospital discharge codes. Inverse probability weighting was used to adjust for confounding, and Cox models to estimate hazard ratios (HRs). Survival curves were estimated using weighted Kaplan-Meier estimators.

RESULTS

We identified 1 143 948 new users of PPIs and 36 229 new users of H₂ RAs who were free of prevalent cardiovascular or cerebrovascular disease. The mean follow-up time was 6.2 years for PPI initiators and 5.3 years for H₂ RA initiators. After 10 years, the HRs for MI and IS were 0.96 (95% confidence interval (CI): 0.80-1.16) and 0.98 (95% CI: 0.89-1.08), respectively.

CONCLUSIONS

This analysis of claims data of a large German health insurer did not provide evidence that PPI therapy increased the risk of MI or IS in the first decade after treatment initiation.

The Use of Active Comparators in Self-Controlled Designs

For self-controlled studies of medication-related effects, time-varying confounding by indication can occur if the indication varies over time. We describe how active comparators might mitigate such bias, using an empirical example. Approaches to using active comparators are described for case-crossover design, case-time-control design, self-controlled case-series, and sequence symmetry analyses. In the empirical example, we used Danish data from 1996-2018 to study the association between penicillin and venous thromboembolism (VTE), using roxithromycin, a macrolide antibiotic, as comparator. Upper respiratory infection is a transient risk factor for VTE, thus representing time-dependent confounding by indication. Odds ratios for case-crossover analysis were 3.35 (95% confidence interval: 3.23, 3.49) for penicillin and 3.56 (95% confidence interval: 3.30, 3.83) for roxithromycin. We used a Wald-based method or an interaction term to estimate the odds ratio for penicillin with roxithromycin as comparator. These 2 estimates were 0.94 (95% confidence interval: 0.87, 1.03) and 1.03 (95% confidence interval: 0.95, 1.13). Results were similar for the case-time-control analysis, but both the self-controlled case-series and sequence symmetry analysis suggested a weak protective effect of penicillin, seemingly explained by VTE affecting future exposure exclusively for penicillin. The strong association of antibiotics with VTE suggests presence of confounding by indication. Such confounding can be mitigated by using an active comparator.

The effect of sodium-glucose transport protein 2 inhibitors on mortality and heart failure in randomized trials versus observational studies

AIM

Randomized clinical trials (RCTs) allocating type 2 diabetes patients to treatment with sodium-glucose transport protein 2 (SGLT-2) inhibitors or placebo have found significant effects on the risk of heart failure and modest effects on mortality. In the wake of the first trials, a number of observational studies have been conducted, some of these reporting a mortality reduction of 50% compared to active comparators. In this review, we systematically assess and compare the results on all-cause mortality, cardiovascular mortality and heart failure hospitalization observed in RCTs with the results obtained in observational studies.

METHOD

We performed a systematic bibliographical search including cardiovascular outcome trials and observational studies assessing the effect of SGLT-2 inhibitors on mortality and heart failure.

RESULTS

Seven RCTs and 23 observational studies were included in the current review. The observed heterogeneity between study results for all-cause mortality (p-interaction < 0.001) and cardiovascular mortality (p-interaction < 0.001) was explained by study type, whereas this was not the case for heart failure (p-interaction = 0.18).

CONCLUSION

Methodological considerations such as the omission of important confounders, immortal-time bias and residual confounding such as unmeasured social economic inequality may be the cause of the inflated results observed in observational studies and that calls for caution when observational studies are used to guide treatment of patients with type 2 diabetes.

Association of Adverse Events with Antibiotic Treatment for Urinary Tract Infection

BACKGROUND

Little is known about the relative harms of different antibiotic regimens prescribed to treat uncomplicated urinary tract infection (UTI). We sought to compare the risk of adverse events associated with commonly-used oral antibiotic regimens for the outpatient treatment of uncomplicated UTI.

METHODS

We identified 1,169,033 otherwise healthy, non-pregnant women aged 18-44 years with uncomplicated UTI who initiated an oral antibiotic with activity against common uropathogens from July 1, 2006 to September 30, 2015. We used propensity score-weighted Kaplan-Meier methods and Cox proportional hazards regression models to estimate the association between antibiotic agent and adverse events.

RESULTS

Of two first-line agents, TMP/SMX (versus nitrofurantoin) was associated with higher risk of several adverse drug events including hypersensitivity reaction (hazard ratio [HR] 2.62, 95% CI 2.30-2.98), acute renal failure (HR 2.56, 95% CI 1.55-4.25), skin rash (HR 2.42, 95% CI 2.13-2.75), urticaria (HR 1.37, 95% CI 1.19-1.57), abdominal pain (HR 1.14, 95% CI 1.09-1.19), and nausea / vomiting (HR 1.18, 95% CI 1.10-1.28), but similar risk of potential microbiome-related adverse events. Compared to nitrofurantoin, non-first-line agents were associated with higher risk of several adverse drug events and potential microbiome-related adverse events including non-C. difficile diarrhea, C. difficile infection, vaginitis / vulvovaginal candidiasis, and pneumonia. Treatment duration modified the risk of potential microbiome-related adverse events.

CONCLUSIONS

The risks of adverse drug events and potential microbiome-related events differ widely by antibiotic agent and duration. These findings underscore the utility of using real-world data to fill evidentiary gaps related to antibiotic safety.

Comparative Effectiveness and Harms of Antibiotics for Outpatient Diverticulitis : Two Nationwide Cohort Studies

BACKGROUND

Outpatient diverticulitis is commonly treated with either a combination of metronidazole and a fluoroquinolone (metronidazole-with-fluoroquinolone) or amoxicillin-clavulanate alone. The U.S. Food and Drug Administration advised that fluoroquinolones be reserved for conditions with no alternative treatment options. The comparative effectiveness of metronidazole-with-fluoroquinolone versus amoxicillin-clavulanate for diverticulitis is uncertain.

OBJECTIVE

To determine the effectiveness and harms of metronidazole-with-fluoroquinolone versus amoxicillin-clavulanate for outpatient diverticulitis.

DESIGN

Active-comparator, new-user, retrospective cohort studies.

SETTING

Nationwide population-based claims data on U.S. residents aged 18 to 64 years with private employer-sponsored insurance (2000 to 2018) or those aged 65 years or older with Medicare (2006 to 2015).

PARTICIPANTS

Immunocompetent adults with diverticulitis in the outpatient setting.

INTERVENTION

Metronidazole-with-fluoroquinolone or amoxicillin-clavulanate.

MEASUREMENTS

1-year risks for inpatient admission, urgent surgery, and Clostridioides difficile infection (CDI) and 3-year risk for elective surgery.

RESULTS

In MarketScan (IBM Watson Health), new users of metronidazole-with-fluoroquinolone (n = 106 361) and amoxicillin-clavulanate (n = 13 160) were identified. There were no differences in 1-year admission risk (risk difference, 0.1 percentage points [95% CI, -0.3 to 0.6]), 1-year urgent surgery risk (risk difference, 0.0 percentage points [CI, -0.1 to 0.1]), 3-year elective surgery risk (risk difference, 0.2 percentage points [CI, -0.3 to 0.7]), or 1-year CDI risk (risk difference, 0.0 percentage points [CI, -0.1 to 0.1]) between groups. In Medicare, new users of metronidazole-with-fluoroquinolone (n = 17 639) and amoxicillin-clavulanate (n = 2709) were identified. There were no differences in 1-year admission risk (risk difference, 0.1 percentage points [CI, -0.7 to 0.9]), 1-year urgent surgery risk (risk difference, -0.2 percentage points [CI, -0.6 to 0.1]), or 3-year elective surgery risk (risk difference, -0.3 percentage points [CI, -1.1 to 0.4]) between groups. The 1-year CDI risk was higher for metronidazole-with-fluoroquinolone than for amoxicillin-clavulanate (risk difference, 0.6 percentage points [CI, 0.2 to 1.0]).

LIMITATION

Residual confounding is possible, and not all harms associated with these antibiotics, most notably drug-induced liver injury, could be assessed.

CONCLUSION

Treating diverticulitis in the outpatient setting with amoxicillin-clavulanate may reduce the risk for fluoroquinolone-related harms without adversely affecting diverticulitis-specific outcomes.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Methods for evaluating the benefit and harms of deprescribing in observational research using routinely collected data

Deprescribing is defined as "the planned and supervised process of dose reduction or stopping of medication that might be causing harm, or no longer be of benefit". Barriers to deprescribing include healthcare professional fear and lack of guidance. These may stem from limited available evidence on benefits and harms of deprescribing medications commonly used among older persons. Advances in pharmacoepidemiology and causal inference methods to evaluate comparative effectiveness and safety of prescribing medications have yet to be considered for deprescribing medication. This paper discusses select methods and how they can be applied to deprescribing research, using case studies of benzodiazepines and low-dose acetylsalicylic acid (aspirin). Target trial emulation involves the explicit application of design principles from randomised controlled trials to observational studies. Several design aspects, including defining eligibility criteria and time zero, require additional considerations for deprescribing studies. The active comparator new user design also presents challenges, including selection of an appropriate comparator. This paper discusses these aspects, and others, in relation to deprescribing studies. Furthermore, methods proposed to control for confounding, in particular, the prior event rate ratio and propensity scores, are discussed. Introduction of billing codes or mechanisms for accurately determining when deprescribing has occurred would enhance the ability to conduct research using routinely collected data. Although the approaches discussed in this paper may strengthen observational studies of deprescribing, their use may be best suited to certain scenarios or research questions, where randomised controlled trials may be less feasible.

The role of the renin-angiotensin system inhibitors in malignancy: a review

Hypertension is one of the most prevalent diseases in cardiology. The angiotensin receptor blockers (ARBs)/angiotensin converting enzyme inhibitors (ACEIs) are widely used drugs to stabilize the blood pressure via inhibition of the renin-angiotensin system (RAS). Studies have found that the exposure to RAS inhibitors (RASi) can suppress the development of cancers via multimodal mechanisms and has attracted increased attentions in the recent past. Owing the potential of RASi to inhibit tumor growth, proliferation and metastasis, they are considered as the potential and exciting candidates to enhance the effect of chemo-radiotherapy and targeted therapy efficacy. However, there are conflicting reports as to the use of ARB/ACEI in all facets of tumor growth. In this study, we comprehensively summarize and review the potential mechanisms of RASi in cancer treatment, like inhibition of tumor angiogenesis, reduction of cancer-associated fibroblasts (CAFs) and extracellular matrix (ECM), regulation of immune cells and improvement of hypoxia. Additionally, based on the basic and clinical experiments, we analyze the views and results regarding the role of RASi plays in tumor from genesis to recurrence, and certainly cancer treatment (chemo-radiotherapy and targeted therapy). In the last, not only do we discuss the prospects of using RASi to enhance cancer treatment efficacy but also point out the conflicting situation with the intention to give some directions and inspiration on this topic.

Association Between Angiotensin II Receptor Blockers and the Risk of Lung Cancer Among Patients With Hypertension From the Korean National Health Insurance Service-National Health Screening Cohort

Objectives:

The objective of this study was to estimate the risk of lung cancer in relation to angiotensin II receptor blocker (ARB) use among patients with hypertension from the Korean National Health Insurance Service-National Health Screening Cohort.

Methods:

We conducted a retrospective cohort study of patients with hypertension who started to take antihypertensive medications and had a treatment period of at least 6 months. We calculated the weighted hazard ratios (HRs) and their 95% confidence intervals (CIs) of lung cancer associated with ARB use compared with calcium channel blocker (CCB) use using inverse probability treatment weighting.

Results:

Among a total of 60 469 subjects with a median follow-up time of 7.8 years, 476 cases of lung cancer were identified. ARB use had a protective effect on lung cancer compared with CCB use (HR, 0.75; 95% CI, 0.59 to 0.96). Consistent findings were found in analyses considering patients who changed or discontinued their medication (HR, 0.50; 95% CI, 0.32 to 0.77), as well as for women (HR, 0.56; 95% CI, 0.34 to 0.93), patients without chronic obstructive pulmonary disease (HR, 0.75; 95% CI, 0.56 to 1.00), never-smokers (HR, 0.64; 95% CI, 0.42 to 0.99), and non-drinkers (HR, 0.69; 95% CI, 0.49 to 0.97). In analyses with different comparison antihypertensive medications, the overall protective effects of ARBs on lung cancer risk remained consistent.

Conclusions:

The results of the present study suggest that ARBs could decrease the risk of lung cancer. More evidence is needed to establish the causal effect of ARBs on the incidence of lung cancer.

Association of Infections and Use of Fluoroquinolones With the Risk of Aortic Aneurysm or Aortic Dissection

IMPORTANCE

Prior observational studies have suggested that fluoroquinolone use may be associated with more than 2-fold increased risk of aortic aneurysm or aortic dissection (AA/AD). These studies, however, did not fully consider the role of coexisting infections and the risk of fluoroquinolones relative to other antibiotics.

OBJECTIVE

To estimate the risk of AA/AD associated with infections and to assess the comparative risk of AA/AD associated with fluoroquinolones vs other antibiotics with similar indication profiles among patients with the same types of infections.

DESIGNS, SETTINGS, AND PARTICIPANTS

This nested case-control study identified 21 651 176 adult patients from a nationwide population-based health insurance claims database from January 1, 2009, to November 30, 2015. Each incident case of AA/AD was matched with 10 control individuals by age, sex, and follow-up duration in the database using risk-set sampling. Analysis of the data was conducted from April 2019 to March 2020.

EXPOSURES

Infections and antibiotic use within a 60-day risk window before the occurrence of AA/AD.

MAIN OUTCOMES AND MEASURES

Conditional logistic regression was used to estimate the odds ratios (ORs) and 95% CIs comparing infections for which fluoroquinolones are commonly used with no infection within a 60-day risk window before outcome occurrence, adjusting for baseline confounders and concomitant antibiotic use. The adjusted ORs comparing fluoroquinolones with antibiotics with similar indication profiles within patients with indicated infections were also estimated.

RESULTS

A total of 28 948 cases and 289 480 matched controls were included (71.37% male; mean [SD] age, 67.41 [15.03] years). Among these, the adjusted OR of AA/AD for any indicated infections was 1.73 (95% CI, 1.66-1.81). Septicemia (OR, 3.16; 95% CI, 2.63-3.78) and intra-abdominal infection (OR, 2.99; 95% CI, 2.45-3.65) had the highest increased risk. Fluoroquinolones were not associated with an increased AA/AD risk when compared with combined amoxicillin-clavulanate or combined ampicillin-sulbactam (OR, 1.01; 95% CI, 0.82-1.24) or with extended-spectrum cephalosporins (OR, 0.88; 95% CI, 0.70-1.11) among patients with indicated infections. The null findings for fluoroquinolone use remained robust in different subgroup and sensitivity analyses.

CONCLUSIONS AND RELEVANCE

These results highlight the importance of accounting for coexisting infections while examining the safety of antibiotics using real-world data; the findings suggest that concerns about AA/AD risk should not deter fluoroquinolone use for patients with indicated infections.

Renin-Angiotensin-Aldosterone System-based Antihypertensive Agents and the Risk of Colorectal Cancer Among Medicare Beneficiaries

BACKGROUND

Biologic evidence suggests that angiotensin II may play a role in tumor progression or growth. We compared the short-term colorectal cancer (CRC) risk among initiators of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) versus guideline-recommended clinical alternatives (beta blockers, calcium channel blockers [CCB], and thiazides).

METHODS

We conducted a new-user cohort study on U.S. Medicare beneficiaries aged over 65 years, who initiated antihypertensive monotherapy during 2007-2013 and were free of cancer diagnosis before drug initiation. Follow-up began 6 months postinitiation to allow time for the diagnostic delay. We estimated hazard ratios (HR) with 95% confidence intervals (CI) using propensity score weighted Cox regression, overall and stratified by time since drug initiation, and 5-year cumulative risk differences (RD) using Kaplan-Meier estimator. We assessed the potential for unmeasured confounding using supplemental data from Medicare Current Beneficiary Survey.

RESULTS

For analyses without censoring for treatment changes, we observed 532 CRC events among 111,533 ACEI/ARB initiators. After a median follow-up of 2.2 years (interquartile range: 1.0-3.7), CRC risk was similar between ACEI/ARB and active comparators, with adjusted HRs of 1.0 (95% CI = 0.85, 1.1) for ACEI/ARB versus beta blockers, 1.2 (95% CI = 0.97, 1.4) for ACEI/ARB versus CCB and 1.0 (95% CI = 0.80, 1.3) for ACEI/ARB versus thiazide. Five-year RDs and as-treated analyses, which censored follow-up at medication changes, produced similar findings.

CONCLUSIONS

Based on real-world antihypertensive utilization patterns in Medicare beneficiaries, our study suggests no association between ACEI/ARB initiation and the short-term CRC risk.

Methodological considerations when analysing and interpreting real-world data

In the absence of relevant data from randomized trials, nonexperimental studies are needed to estimate treatment effects on clinically meaningful outcomes. State-of-the-art study design is imperative for minimizing the potential for bias when using large healthcare databases (e.g. claims data, electronic health records, and product/disease registries). Critical design elements include new-users (begin follow-up at treatment initiation) reflecting hypothetical interventions and clear timelines, active-comparators (comparing treatment alternatives for the same indication), and consideration of induction and latent periods. Propensity scores can be used to balance measured covariates between treatment regimens and thus control for measured confounding. Immortal-time bias can be avoided by defining initiation of therapy and follow-up consistently between treatment groups. The aim of this manuscript is to provide a non-technical overview of study design issues and solutions and to highlight the importance of study design to minimize bias in nonexperimental studies using real-world data.