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L Penning de Vries BB, Groenwold RHH. Identification of causal effects in case-control studies. BMC Med Res Methodol 2022; 22:7. [PMID: 34996386 PMCID: PMC8742362 DOI: 10.1186/s12874-021-01484-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/29/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Case-control designs are an important yet commonly misunderstood tool in the epidemiologist's arsenal for causal inference. We reconsider classical concepts, assumptions and principles and explore when the results of case-control studies can be endowed a causal interpretation. RESULTS We establish how, and under which conditions, various causal estimands relating to intention-to-treat or per-protocol effects can be identified based on the data that are collected under popular sampling schemes (case-base, survivor, and risk-set sampling, with or without matching). We present a concise summary of our identification results that link the estimands to the (distribution of the) available data and articulate under which conditions these links hold. CONCLUSION The modern epidemiologist's arsenal for causal inference is well-suited to make transparent for case-control designs what assumptions are necessary or sufficient to endow the respective study results with a causal interpretation and, in turn, help resolve or prevent misunderstanding. Our approach may inform future research on different estimands, other variations of the case-control design or settings with additional complexities.
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Affiliation(s)
- Bas B L Penning de Vries
- Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, PO Box 9600, 2300 RC, The Netherlands.
| | - Rolf H H Groenwold
- Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, PO Box 9600, 2300 RC, The Netherlands.,Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands
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Hsu SC, Chang SS, Lee MTG, Lee SH, Tsai YW, Lin SC, Chen ST, Weng YC, Porta L, Wu JY, Lee CC. Risk of gastrointestinal perforation in patients taking oral fluoroquinolone therapy: An analysis of nationally representative cohort. PLoS One 2017; 12:e0183813. [PMID: 28873440 PMCID: PMC5584983 DOI: 10.1371/journal.pone.0183813] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 08/13/2017] [Indexed: 01/14/2023] Open
Abstract
Background Fluoroquinolone is a commonly prescribed antimicrobial agent, and up to 20% of its users registers adverse gastroenterological symptoms. We aimed to evaluate the association between use of fluoroquinolone and gastrointestinal tract perforation. Methods We conducted a nested case-control study on a national health insurance claims database between 1998 and 2011. The use of fluoroquinolones was classified into current (< 60 days), past (61–365 days prior to the index date) and any prior year use of fluoroquinolones. We used the conditional logistic regression model to estimate rate ratios (RRs), adjusting or matching by a disease risk score (DRS). Results We identified a cohort of 17,510 individuals diagnosed with gastrointestinal perforation and matched them to 1,751,000 controls. Current use of fluoroquinolone was associated with the greatest increase in risk of gastrointestinal perforations after DRS score adjustment (RR, 1.90; 95% CI, 1.62–2.22). The risk of gastrointestinal perforation was attenuated for past (RR, 1.33; 95% CI, 1.20–1.47) and any prior year use (RR, 1.46; 95% CI, 1.34–1.59). To gain insights into whether the observed association can be explained by unmeasured confounder, we compared the risk of gastrointestinal perforation between fluoroquinolone and macrolide. Use of macrolide, an active comparator, was not associated with a significant increased risk of gastrointestinal perforation (RR, 1.11, 95%CI, 0.15–7.99). Sensitivity analysis focusing on perforation requiring in-hospital procedures also demonstrated an increased risk associated with current use. To mitigate selection bias, we have also excluded people who have never used fluoroquinolone before or people with infectious colitis, enteritis or gastroenteritis. In both of the analysis, a higher risk of gastrointestinal perforation was still associated with the use of fluoroquinolone. Conclusions We found that use of fluoroquinolones was associated with a non-negligible increased risk of gastrointestinal perforation, and physicians should be aware of this possible association.
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Affiliation(s)
- Shou-Chien Hsu
- Department of Emergency Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Shy-Shin Chang
- Department of Family Medicine, Taipei Medical University Hospital and School of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Meng-tse Gabriel Lee
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Si-Huei Lee
- Department of Rehabilitation and Physical Medicine, Taipei Veteran General Hospital, Taipei, Taiwan
- Department of Medicine, College of Medicine, National Yang Ming University, Taipei, Taiwan
| | - Yi-Wen Tsai
- Department of Family Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Shen-Che Lin
- Department of Emergency Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Szu-Ta Chen
- Department of Pediatrics, National Taiwan University Hospital Yun-Lin Branch, Douliou, Taiwan
- Department of Pediatrics, National Taiwan University and College of Medicine, Taipei, Taiwan
- Graduate Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Chieh Weng
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Lorenzo Porta
- Dipartimento di scienze Biomediche e Cliniche, Ospedale "L. Sacco", Università degli Studi di Milano, Milan, Italy
| | - Jiunn-Yih Wu
- Department of Emergency Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan and Chang Gung University College of Medicine, Taoyuan, Taiwan
- * E-mail: (JYW); (CCL)
| | - Chien-Chang Lee
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
- * E-mail: (JYW); (CCL)
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Seymour JF, Döhner H, Minden MD, Stone R, Gambini D, Dougherty D, Beach C, Weaver J, Dombret H. Incidence rates of treatment-emergent adverse events and related hospitalization are reduced with azacitidine compared with conventional care regimens in older patients with acute myeloid leukemia. Leuk Lymphoma 2016; 58:1412-1423. [DOI: 10.1080/10428194.2016.1243680] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- John F. Seymour
- Peter MacCallum Cancer Center, University of Melbourne, Parkville, Melbourne, Australia
| | | | | | | | | | | | | | | | - Hervé Dombret
- Hôpital Saint Louis, Institut Universitaire d’Hématologie, Paris, France
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Pazianas M, Abrahamsen B, Wang Y, Russell RGG. Incidence of fractures of the femur, including subtrochanteric, up to 8 years since initiation of oral bisphosphonate therapy: a register-based cohort study using the US MarketScan claims databases. Osteoporos Int 2012; 23:2873-84. [PMID: 22431012 DOI: 10.1007/s00198-012-1952-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 01/04/2012] [Indexed: 10/28/2022]
Abstract
UNLABELLED In a cohort study of users of bisphosphonates, we evaluated the incidence of fragility fractures at all sites on the femur following for up to 8 years of therapy with alendronate or risedronate. We did not find evidence for a reversal of fracture protection with long-term use of bisphosphonates. INTRODUCTION Few studies have acquired adequate data with prolonged follow-up on bisphosphonate users in the general population to evaluate their long-term effects on the risk of hip fractures including those in the subtrochanteric region. METHODS This cohort study utilizes a large USA database (January 1, 2000 to June 30, 2009). We compared patients with higher versus lower degrees of compliance [medication possession ratio, MPR <1/3 (the reference), 1/3-<2/3, or ≥ 2/3]. Radiographic adjudication of fracture site and features were not performed. Hazard ratios (HR) for fracture were estimated using time-dependent Cox models. Restricted cubic splines (RCS) were used to plot HRs for fracture against duration of therapy. RESULTS There were 3,655 incident cases of femoral fracture (764 subtrochanteric/shaft, 2,769 hip) identified during 917,741 person-years of follow-up (median = 3 years) on 287,099 patients (267,374 were women) from the date when they initiated oral bisphosphonate therapy. The corresponding HRs (95% confidence interval, CI) for overall femoral fractures associated with each additional year of therapy were 0.93 (0.86-1.01) within 5 years, and 0.89 (0.77-1.03) beyond 5 years for risedronate and 0.86 (0.81-0.91) and 0.95 (0.84-1.07) for alendronate, respectively. The corresponding estimates for subtrochanteric/shaft fractures were 1.05 (0.87-1.26) and 0.89 (0.60-1.33) for risedronate and 0.99 (0.92-1.05) and 1.05 (0.92-1.20) for alendronate, respectively. The HRs (95% CI) for overall femoral fractures associated with each additional year of alendronate or risedronate therapy within 5 and beyond 5 years were not significantly different. CONCLUSION Our study showed persistence of overall hip fracture protection with long-term use of alendronate or risedronate.
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Affiliation(s)
- M Pazianas
- The Botnar Research Centre, Oxford University, Oxford, UK.
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Hebert C, Delaney JAC, Hemmelgarn B, Lévesque LE, Suissa S. Benzodiazepines and elderly drivers: a comparison of pharmacoepidemiological study designs. Pharmacoepidemiol Drug Saf 2007; 16:845-9. [PMID: 17563091 DOI: 10.1002/pds.1432] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
PURPOSE Contradictory results were published from two studies in the late 1990s about the effects of long half-life benzodiazepine use on the risk of motor vehicle crashes (MVCs) in the elderly. The use of different study designs could explain the differences observed in these studies. METHODS The results of an unmatched case-control study were compared to those of a case-crossover study using the same prescription claims database to determine whether the current use of benzodiazepines increased the risk of MVCs. RESULTS There were 5579 cases and 12 911 controls identified between the years 1990 and 1993 in the province of Quebec, Canada. The case-control approach demonstrated an increased rate of injurious MVC associated with the current use of long-acting benzodiazepines [odds ratio (OR) 1.45; 95% confidence interval (CI): 1.12-1.88]. The case-crossover approach applied to all cases did not show any association [OR 0.99; 95%CI: 0.83-1.19]. However, among the cases restricted to subjects with four or less prescriptions filled in the previous year, corresponding more to transient exposures, the OR was elevated [OR 1.53; 95%CI: 1.08-2.16]. CONCLUSIONS Differences in study design and analysis may explain some of the discrepancies in previous results. Both study designs provide evidence that long-acting benzodiazepines appear to be associated with an increased risk of MVC.
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Affiliation(s)
- Caroline Hebert
- Division of Clinical Epidemiology, McGill University Health Center, Montreal, Canada
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