Association between antidepressants and the risk of diabetic foot ulcers and amputation in antidepressant-naïve type 2 diabetes mellitus patients: A nested case-control study

AIMS

Antidepressants are widely used by individuals with type 2 diabetes mellitus (T2DM). This study aimed to explore the correlation between antidepressant use, considering specific antidepressant subclasses or cumulative doses, and diabetic foot ulcer (DFU) risk.

METHODS

This nested case-control study was conducted using a representative population-based Korean cohort database from 2002 to 2019. Participants with DFUs were matched with participants without DFUs based on age, sex, date of T2DM diagnosis, and follow-up duration. In total, 791 DFUs and 3900 controls were included. The association between antidepressant use or cumulative dose of each antidepressant subclass, DFU risk and amputation risk was examined using a conditional logistic regression model.

RESULTS

Antidepressant ever-use was associated with an increased incidence of DFUs compared with non-use. Furthermore, an increase in DFU risk was evident with increasing cumulative antidepressant dosage, particularly among tricyclic antidepressant (TCA) ever-users and selective serotonin reuptake inhibitors (SSRIs) ever-users. Additionally, antidepressant ever-users displayed a higher risk of DFUs requiring amputation, which was consistently observed when the cumulative dosages of overall antidepressants and TCAs were considered.

CONCLUSION

Caution is advised when administering TCAs and SSRIs in antidepressant-naïve T2DM patients to reduce DFU and the consequent amputation risk.

Carotid intima-media thickness in adults with and without psoriasis - a nested case-control study from baseline data of ELSA-Brasil cohort

There is a lack of consensus about the association between psoriasis (PSO) and carotid intima-media thickness (cIMT) in literature, since previous studies considered dermatologic clinic patients or general population. This study aimed to compare cIMT levels according to PSO in a sample of 10,530 civil servants form the ELSA-Brasil cohort study and analyze its association with the disease. The PSO cases and disease duration were identified by medical diagnosis self-reported at study enrollment. A paired group was identified by propensity score matching among all the participants without PSO. Mean cIMT values were considered for continuous analysis while cIMT above 75th percentile was considered for categorical analysis. Multivariate conditional regression models were used to analyze association between cIMT and PSO diagnosis, by comparing PSO cases against paired controls and overall sample without disease. A total of n = 162 PSO cases were identified (1.54%) and no difference in cIMT values was observed between participants with PSO and overall sample or control group. PSO was not associated with linear increment of cIMT (vs. overall sample: β = 0.003, p = 0.690; vs. matched controls: β = 0.004, p = 0.633) neither with increased chance of having cIMT above 75th percentile (vs. overall sample: OR = 1.06, p = 0.777; vs. matched controls: OR = 1.19, p = 0.432; conditional regression: OR = 1.31, p = 0.254). There was no relationship between disease duration and cIMT (β = 0.000, p = 0.627). Although no significant relationship between mild cases of psoriasis and cIMT was observed among a wide cohort of civil servants, longitudinal investigation about cIMT progression and severity of disease are still needed.

Does early surgery prevent Postoperative ICU admission after surgery for the fracture of the hip. Nested case control study of 911 patients

Introduction

Since most hip fractures are treated surgically, it is imperative to find an optimum fracture-to-surgery time to decrease the potential complications and enhance postoperative outcomes. In comparison to the vast plethora of literature available on surgical delay and its implications on mortality, very little, if any, research is available on the impact of delayed surgery on postoperative ICU admission. The primary objective of our study is to examine the factors influencing post-surgical ICU admission in order to work on preventive strategies to reduce the potential associated morbidity.

Material and methods

Investigators did a nested case control study in a university hospital. A case was defined as a patient who had postoperative ICU admission while controls were patients who did not have postoperative ICU admission after hip fracture surgery. The primary outcome variable was postoperative ICU admission. The exposure variable was defined as the time to surgery which was categorized into two categories; early and late; the early surgery included patients who were operated within ≤ 48 h and the late included patients who had their surgery >48 h. Information on potential confounders including age, type of the procedure and comorbidities were also obtained. Result reported in-line with STROCSS criteria.

Results

A total cohort of 1084 hip fracture surgeries were performed from January 2010 to December 2018. After screening for eligibility criteria, 911 patients were eligible for the final simple logistic regression analysis (48 cases and 863 controls). Our exposure variable i.e. time from admission to surgery showed no difference between cases and controls. The odds of being treated with Hemiarthroplasty among cases admitted in ICU was 2.42 times as compared to controls (aOR = 2.42; 95% C.I. 1.21–4.86).

Conclusion

Our study did not find an association between surgical delay and post-operative ICU admission after accounting for other covariates and potential confounders.

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There is a controversy of the benefits of early hip fracture surgery.

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Delay in surgery is postulated to carry higher risk of postoperative ICU admission.

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However, this higher risk was statistically insignificant in the current study.

Application of the matched nested case-control design to the secondary analysis of trial data

BACKGROUND

A nested case-control study is an efficient design that can be embedded within an existing cohort study or randomised trial. It has a number of advantages compared to the conventional case-control design, and has the potential to answer important research questions using untapped prospectively collected data.

METHODS

We demonstrate the utility of the matched nested case-control design by applying it to a secondary analysis of the Abnormal Doppler Enteral Prescription Trial. We investigated the role of milk feed type and changes in milk feed type in the development of necrotising enterocolitis in a group of 398 high risk growth-restricted preterm infants.

RESULTS

Using matching, we were able to generate a comparable sample of controls selected from the same population as the cases. In contrast to the standard case-control design, exposure status was ascertained prior to the outcome event occurring and the comparison between the cases and matched controls could be made at the point at which the event occurred. This enabled us to reliably investigate the temporal relationship between feed type and necrotising enterocolitis.

CONCLUSIONS

A matched nested case-control study can be used to identify credible associations in a secondary analysis of clinical trial data where the exposure of interest was not randomised, and has several advantages over a standard case-control design. This method offers the potential to make reliable inferences in scenarios where it would be unethical or impractical to perform a randomised clinical trial.

Hospitalization, surgery, and incident dementia

INTRODUCTION

We evaluated whether hospitalization with or without surgery increases risk for dementia or Alzheimer's disease.

METHODS

A clinical sample (843 clinically diagnosed dementia cases; 1686 matched nondemented individuals) was identified from Swedish Twin Registry studies. A register-based sample (4293 cases; 21,465 matched controls) was identified by linkage of Swedish Twin Registry to Swedish Patient Registry records. Apolipoprotein E (APOE) status and within-pair comparisons of dementia discordant twins indicated genetic susceptibility.

RESULTS

Nonsurgical hospitalization is associated with greater dementia risk than hospitalization with surgical intervention. In the register sample, thoracic, abdominal, and major orthopedic procedures entailed dementia risk; in the clinical sample, orthopedic alone. Within-pair analyses indicate that associations in part reflect genetic susceptibility in common to hospitalization and dementia. Potential gene-environment interactions were indicated by greater risk due to hospitalization among APOE ε4 noncarriers.

DISCUSSION

We confirm hospitalization as a risk factor for dementia, with repeated hospitalizations a more important risk factor than surgery.

Impact of oral osteoarthritis therapy usage among other risk factors on knee replacement: a nested case-control study using the Osteoarthritis Initiative cohort

BACKGROUND

The aim of this study was to measure the association between exposure to commonly used oral osteoarthritis (OA) therapies and relevant confounding risk factors on the occurrence of knee replacement (KR), using the Osteoarthritis Initiative (OAI) database.

METHODS

In this nested case-control design study, participants who had a KR after cohort entry were defined as "cases" and were matched with up to four controls for age, gender, income, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, Kellgren-Lawrence grade, and duration of follow up. Exposure to oral OA therapies (acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase-2 (COX-2) inhibitors, narcotics, and glucosamine/chondroitin sulfate) was determined within the 3 years prior to the date of the KR. Conditional regression analyses were performed to estimate the association between KR and exposure to oral OA therapies and other potential confounding risk factors.

RESULTS

A total of 218 participants who underwent a KR (cases) were matched to 540 controls. The median time to KR was 4.3 years among cases. The majority in both groups were Caucasian with mean age of 69 years and 61% were female. Numerically, cases were more exposed to acetaminophen, NSAIDs, and COX-2 inhibitors. Exposure to narcotics and glucosamine/chondroitin sulfate was relatively similar between cases and controls. No significant association was found between the occurrence of KR and exposure to any of the oral OA therapies within the 3 years prior to KR. A significantly higher occurrence of KR was found in Caucasian subjects (OR 1.84; 95% CI, 1.13-2.99; p = 0.015) and subjects with body mass index (BMI) ≥ 27 kg/m² (OR 1.65; 95% CI, 1.06-2.58; p = 0.027).

CONCLUSION

This study provides evidence that the main risk factors leading to KR are disease severity, symptoms and high BMI. Importantly, exposure to oral OA therapies was not associated with the occurrence of KR.

Associations between ambient air pollution and daily mortality in a cohort of congestive heart failure: Case-crossover and nested case-control analyses using a distributed lag nonlinear model

BACKGROUND

Persons with congestive heart failure may be at higher risk of the acute effects related to daily fluctuations in ambient air pollution. To meet some of the limitations of previous studies using grouped-analysis, we developed a cohort study of persons with congestive heart failure to estimate whether daily non-accidental mortality were associated with spatially-resolved, daily exposures to ambient nitrogen dioxide (NO₂) and ozone (O₃), and whether these associations were modified according to a series of indicators potentially reflecting complications or worsening of health.

METHODS

We constructed the cohort from the linkage of administrative health databases. Daily exposure was assigned from different methods we developed previously to predict spatially-resolved, time-dependent concentrations of ambient NO₂ (all year) and O₃ (warm season) at participants' residences. We performed two distinct types of analyses: a case-crossover that contrasts the same person at different times, and a nested case-control that contrasts different persons at similar times. We modelled the effects of air pollution and weather (case-crossover only) on mortality using distributed lag nonlinear models over lags 0 to 3 days. We developed from administrative health data a series of indicators that may reflect the underlying construct of "declining health", and used interactions between these indicators and the cross-basis function for air pollutant to assess potential effect modification.

RESULTS

The magnitude of the cumulative as well as the lag-specific estimates of association differed in many instances according to the metric of exposure. Using the back-extrapolation method, which is our preferred exposure model, we found for the case-crossover design a cumulative mean percentage changes (MPC) in daily mortality per interquartile increment in NO₂ (8.8 ppb) of 3.0% (95% CI: -0.4, 6.6%) and for O₃ (16.5 ppb) 3.5% (95% CI: -4.5, 12.1). For O₃ there was strong confounding by weather (unadjusted MPC = 7.1%; 95% CI: 1.7, 12.7%). For the nested case-control approach the cumulative MPC for NO₂ in daily mortality was 2.9% (95% CI: -0.9, 6.9%) and for O₃ 7.3% (95% CI: 3.0, 11.9%). We found evidence of effect modification between daily mortality and cumulative NO₂ and O₃ according to the prescribed dose of furosemide in the nested case-control analysis, but not in the case-crossover analysis.

CONCLUSIONS

Mortality in congestive heart failure was associated with exposure to daily ambient NO₂ and O₃ predicted from a back-extrapolation method using a land use regression model from dense sampling surveys. The methods used to assess exposure can have considerable influence on the estimated acute health effects of the two air pollutants.

Alternative statistical methods and their application to research in intensive care setting

In nested case-control studies, sampling of controls is usually done by density of incidence and pairing. With regard to the classic control cases studies, nested ones are more efficient, allow the calculation of the incidence of the disease and they have more internal validity due to the lower presence of bias. Competitive risks techniques can be used if we study different types of events and focus on the time and type of the first event. Recursive partitioning is a type of multivariate analysis whose purpose is the construction of classification algorithms, and it is especially useful when there are a large number of predictive variables with complex relationships with the event.

Association between sleep disorder and panic disorder in South Korea: Nationwide nested case-control study of data from 2004 to 2013

After 2010, panic disorders became relatively common in South Korea, with many celebrities confessing to the public that they have panic disorder. The annual number of patients with panic disorder and sleep disorder have been gradually increasing. In light of these increases, we analyzed the relationship between sleep disorder and panic disorder. We used national claim data to design a 1:3 nested case-control study. The study included medical claims filed for 29,312 patients during 2004-2013. We performed conditional logistic regression analysis to investigate the relationship between sleep disorder and panic disorder. There were 7436 patients who were diagnosed with panic disorder, and 21,876 patients who were gender- and age-matched as controls. Patients with sleep disorder had higher incidence of panic disorder. In particular, patients with insomnia had the strongest association with panic disorder (adjusted, OR, 1.386; 95% CI, 1.201-1.599; p < 0.05). These associations were stronger in healthy patients and those with worse socioeconomic status. In conclusion, sleep disorder, in particular, insomnia was positively associated with panic disorder. Thus, healthcare professionals and policy makers should effectively control insomnia and consider strategies for early intervention for vulnerable patients with risk of panic disorder.

Distant and proximate factors associated with maternal near-miss: a nested case-control study in selected public hospitals of Addis Ababa, Ethiopia

Background

Ethiopia is one of the sub-Saharan Africa countries with the highest maternal mortality. Maternal near-misses are more common than deaths and statistically stronger for a comprehensive analysis of the determinants. The study aimed to identify the factors associated with maternal near-miss in selected public hospitals of Addis Ababa, Ethiopia.

Methods

We conducted a nested case-control study in five selected public hospitals of Addis Ababa, Ethiopia from May 1, 2015 to April 30, 2016. Participants were interviewed by well-trained data collectors using pre-tested questionnaire. Medical records were also reviewed to gather relevant information. World Health Organization criteria were used to identify maternal near-miss cases. A total of three controls matched for age and study area was selected for each maternal near-miss case. Bivariate and multivariable conditional logistic regressions were performed using Stata version 13.0.

Results

A total of 216 maternal near-miss cases and 648 controls were included in the study. The main factors associated with maternal near-miss were: history of chronic hypertension (AOR = 10.80,95% CI; 5.16–22.60), rural residency (AOR = 10.60,95% CI;4.59–24.46), history of stillbirth (AOR = 6.03,95% CI;2.09–17.41), no antenatal care attendance (AOR = 5.58,95% CI;1.94–16.07) and history of anemia (AOR = 5.26,95% CI;2.89–9.57).

Conclusions

There is a need for appropriate interventions in order to improve the identified factors. The factors can be modified through a better access to medical and maternity care, scaling up of antenatal care in rural areas, improve in infrastructure to fulfill referral chain from primary level to secondary and tertiary health care levels, and health education to pregnant women.

Are there risk factors for false-positive malformation diagnoses on obstetric ultrasound? A nested case-control study

INTRODUCTION

In a population-based study, we found an overall false-positive rate of 8.8% for the second and third trimester ultrasounds. Although numerous studies have been performed to examine factors which lead to false negatives, the same is not true for the factors associated with false positives. The principal objective of this study was to look for risk factors for false-positive diagnoses of fetal malformations on obstetric ultrasound scans.

MATERIAL AND METHODS

In this nested case-control study, the case infants were those whose mother had a false-positive antenatal ultrasound diagnosis of a malformation during the second or third trimester (ultrasound false-positives) and who were live - or stillborn in Auvergne in 2006-2010. The control group comprised all children who were ultrasound true-negatives in 2005 and 2007. The study included 46 cases and 184 controls, matched according to the level of the maternity unit in which they were born.

RESULTS

Most false-positive diagnoses were minor malformations. The mean term at this false-positive diagnosis was 27.7±5.4 weeks; in 46.8% of cases, the diagnosis was made during the second-trimester ultrasound. A single malformation was suspected in 95.7% of the cases. In 97.9% of cases, only one anatomical system was affected. In all, 49 malformations were identified among the 46 cases and their distribution differed according to anatomical system. The only risk factor identified was a body mass index (BMI)<25 (ORa=1.7; 95%CI: 1.2-2.4).

DISCUSSION

A maternal BMI<25 was the only risk factor identified for a false-positive ultrasound diagnosis of a fetal malformation.

A new framework for prediction and variable selection for uncommon events in a large prospective cohort study

When prediction is a goal, validation utilizing data outside of the prediction effort is desirable. Typically, data is split into two parts: one for a development and one for validation. But this approach becomes less attractive when predicting uncommon events, as it substantially reduces power. When predicting uncommon events within a large prospective cohort study, we propose the use of a nested case-control design, which is an alternative to the full cohort analysis. By including all cases but only a subset of the non-cases, this design is expected to produce a result similar to the full cohort analysis. In our framework, variable selection is conducted and a prediction model is fit on those selected variables in the case-control cohort. Then, the fraction of true negative predictions (specificity) of the fitted prediction model in the case-control cohort is compared to that in the rest of the cohort (non-cases) for validation. In addition, we propose an iterative variable selection using random forest for missing data imputation, as well as a strategy for a valid classification. Our framework is illustrated with an application featuring high-dimensional variable selection in a large prospective cohort study.

Risk factors for diabetic macular oedema in type 2 diabetes: A case-control study in a United Kingdom primary care setting

AIM

To identify risk factors associated with the development of DMO among patients diagnosed with type 2 diabetes managed in a primary care setting in the UK.

METHODS

A case-control study nested in a cohort of incident Type 2 diabetes identified in The Health Improvement Network database from 2000-2007. Cases were people with DMO (N=211) and controls were a DMO-free sample (N=2194). No age restrictions were applied. Adjusted odds ratios and 95%CIs were estimated (OR; 95%CI).

RESULTS

DMO increased with high alcohol use (2.88; 1.49-5.55), cataracts (4.10; 2.73-6.15), HbA1c ≥7% (1.58; 1.08-2.32), systolic blood pressure ≥160mm Hg (2.03; 1.17-3.53), total cholesterol ≥5mmol/L (1.66; 1.15-2.39), LDL ≥3mmol/L (1.73; 1.14-2.61), and microalbuminuria (1.78; 1.16-2.73). Diuretic drugs were associated with a reduced risk of DMO (0.68; 0.47-0.99), as did smoking (0.47; 0.28-0.77), overweight (0.53; 0.30-0.96) or obesity (0.52; 0.30-0.91) at diabetes diagnosis, and high triglyceride levels (0.51; 0.35-0.74). Patients treated with anti-diabetic drugs showed higher risk of DMO than non-treated patients, particularly those with sulphonylureas (3.40; 2.42-4.78), insulin (3.21; 1.92-5.36) or glitazones (1.88; 1.17-3.04).

CONCLUSION

In patients with type 2 diabetes managed in primary care, multiple factors associated with DMO were identified, such as cataracts, microalbuminuria and high levels of HbA1c, systolic BP, total cholesterol, and LDL. Diuretic drugs were associated with a reduced risk of DMO. Treated diabetes, particularly with sulphonylureas, insulin or glitazones showed highest risk of DMO. The inverse association between smoking, obesity, and triglycerides and DMO deserves further research.

Feasibility of reusing time-matched controls in an overlapping cohort

The methods developed for secondary analysis of nested case-control data have been illustrated only in simplified settings in a common cohort and have not found their way into biostatistical practice. This paper demonstrates the feasibility of reusing prior nested case-control data in a realistic setting where a new outcome is available in an overlapping cohort where no new controls were gathered and where all data have been anonymised. Using basic information about the background cohort and sampling criteria, the new cases and prior data are "aligned" to identify the common underlying study base. With this study base, a Kaplan-Meier table of the prior outcome extracts the risk sets required to calculate the weights to assign to the controls to remove the sampling bias. A weighted Cox regression, implemented in standard statistical software, provides unbiased hazard ratios. Using the method to compare cases of contralateral breast cancer to available controls from a prior study of metastases, we identified a multifocal tumor as a risk factor that has not been reported previously. We examine the sensitivity of the method to an imperfect weighting scheme and discuss its merits and pitfalls to provide guidance for its use in medical research studies.

Efficient estimation for accelerated failure time model under case-cohort and nested case-control sampling

Case-cohort (Prentice, 1986) and nested case-control (Thomas, 1977) designs have been widely used as a cost-effective alternative to the full-cohort design. In this article, we propose an efficient likelihood-based estimation method for the accelerated failure time model under case-cohort and nested case-control designs. An EM algorithm is developed to maximize the likelihood function and a kernel smoothing technique is adopted to facilitate the estimation in the M-step of the EM algorithm. We show that the proposed estimators for the regression coefficients are consistent and asymptotically normal. The asymptotic variance of the estimators can be consistently estimated using an EM-aided numerical differentiation method. Simulation studies are conducted to evaluate the finite-sample performance of the estimators and an application to a Wilms tumor data set is also given to illustrate the methodology.

Reduction in Serum Uric Acid May Be Related to Methotrexate Efficacy in Early Rheumatoid Arthritis: Data from the Canadian Early Arthritis Cohort (CATCH)

OBJECTIVES

The mechanism of action of methotrexate in rheumatoid arthritis (RA) is complex. It may increase adenosine levels by blocking its conversion to uric acid (UA). This study was done to determine if methotrexate lowers UA in early RA (ERA).

METHODS

Data were obtained from Canadian Early Arthritis Cohort, an incident ERA cohort. All ERA patients with serial UA measurements were included, comparing those with methotrexate use vs. no methotrexate exposure (controls). Analyses were exploratory. Patients with concomitant gout or taking UA-lowering therapies were excluded.

RESULTS

In total, 49 of the 2,524 ERA patients were identified with data available for both pre-methotrexate UA levels and post-methotrexate UA levels (300 µmol/L and 273 µmol/L, respectively; P = 0.035). The control group not taking methotrexate had a mean baseline UA level of 280 µmol/L and a follow-up level of 282 µmol/L (P = 0.448); mean change in UA with methotrexate was −26.8 µmol/L vs. 2.3 µmol/L in the no methotrexate group (P = 0.042). Methotrexate users with a decrease in UA had a disease activity score of 2.37 for 28 joints when compared with the controls (3.26) at 18 months (P = 0.042). Methotrexate users with decreased UA had a lower swollen joint count (SJC) of 0.9 at 18 months, whereas methotrexate users without lowering of UA had an SJC of 4.5 (P = 0.035). Other analyses were not significant.

CONCLUSIONS

Methotrexate response is associated with lowering of serum UA in ERA compared to nonusers. This may be due to changes in adenosine levels. Methotrexate response is associated with lower UA and fewer swollen joints compared to nonresponders.