Defining measures of kidney function in observational studies using routine health care data: methodological and reporting considerations

Estimated Effect of Restarting Renin-Angiotensin System Inhibitors after Discontinuation on Kidney Outcomes and Mortality

Key Points

Restarting renin-angiotensin system inhibitor after discontinuation was associated with a lower risk of kidney outcomes and mortality but not related to hyperkalemia. Our findings support a proactive approach to restarting renin-angiotensin system inhibitor among patients with CKD.

Background

While renin-angiotensin system inhibitors (RASi) have been the mainstream treatment for patients with CKD, they are often discontinued because of adverse effects such as hyperkalemia and AKI. It is unknown whether restarting RASi after discontinuation improves clinical outcomes.

Methods

Using the Osaka Consortium for Kidney disease Research database, we performed a target trial emulation study including 6065 patients with an eGFR of 10–60 ml/min per 1.73 m2 who were followed up by nephrologists and discontinued RASi between 2005 and 2021. With a clone-censor-weight approach, we compared a treatment strategy for restarting RASi within a year after discontinuation with that for not restarting RASi. Patients were followed up for 5 years at maximum after RASi discontinuation. The primary outcome was a composite kidney outcome (initiation of KRT, a ≥50% decline in eGFR, or kidney failure [eGFR <5 ml/min per 1.73 m2]). Secondary outcomes were all-cause death and incidence of hyperkalemia (serum potassium levels ≥5.5 mEq/L).

Results

Among those who discontinued RASi (mean [SD] age 66 [15] years, 62% male, mean [SD] eGFR 40 [26] ml/min per 1.73 m2), 2262 (37%) restarted RASi within a year. Restarting RASi was associated with a lower hazard of the composite kidney outcome (hazard ratio [HR], 0.85; 95% confidence intervals [CIs], 0.78 to 0.93]) and all-cause death (HR, 0.70; 95% CI, 0.61 to 0.80) compared with not restarting RASi. The incidence of hyperkalemia did not differ significantly between the two strategies (HR, 1.11; 95% CI, 0.96 to 1.27).

Conclusions

Restarting RASi after discontinuation was associated with a lower risk of kidney outcomes and mortality but not related to the incidence of hyperkalemia.

Individual and neighborhood-level social and deprivation factors impact kidney health in the GLOMMS-CORE study

Prospective cohort studies of kidney equity are limited by a focus on advanced rather than early disease and selective recruitment. Whole population studies frequently rely on area-level measures of deprivation as opposed to individual measures of social disadvantage. Here, we linked kidney health and individual census records in the North of Scotland (Grampian area), 2011-2021 (GLOMMS-CORE) and identified incident kidney presentations at thresholds of estimated glomerular filtration rate (eGFR) under 60 (mild/early), under 45 (moderate), under 30 ml/min/1.73m2 (advanced), and acute kidney disease (AKD). Household and neighborhood socioeconomic measures, living circumstances, and long-term mortality were compared. Case-mix adjusted multivariable logistic regression (living circumstances), and Cox models (mortality) incorporating an interaction between the household and the neighborhood were used. Among census respondents, there were 48546, 29081, 16116, 28097 incident presentations of each respective eGFR cohort and AKD. Classifications of socioeconomic position by household and neighborhood were related but complex, and frequently did not match. Compared to households of professionals, people with early kidney disease in unskilled or unemployed households had increased mortality (adjusted hazard ratios: 95% confidence intervals) of (1.26: 1.19-1.32) and (1.77: 1.60-1.96), respectively with adjustment for neighborhood indices making little difference. Those within either a deprived household or deprived neighborhood experienced greater mortality, but those within both had the poorest outcomes. Unskilled and unemployed households frequently reported being limited by illness, adverse mental health, living alone, basic accommodation, lack of car ownership, language difficulties, and visual and hearing impairments. Thus, impacts of deprivation on kidney health are spread throughout society-complex, serious, and not confined to those living in deprived neighborhoods.

Common mistakes in biostatistics

Biostatistics plays a pivotal role in developing, interpreting and drawing conclusions from clinical, biological and epidemiological data. However, the improper application of statistical methods can lead to erroneous conclusions and misinterpretations. This paper provides a comprehensive examination of the most frequent mistakes encountered in the biostatistical analysis process. We identified and elucidated 10 common errors in biostatistical analysis. These include using the wrong metric to describe data, misinterpreting P-values, misinterpreting the 95% confidence interval, misinterpreting the hazard ratio as an index of prognostic accuracy, ignoring the sample size calculation, misinterpreting analysis by strata in randomized clinical trials, confusing correlation and causation, misunderstanding confounders and mediators, inadequately codifying variables during the data collection, and bias arising when group membership is attributed on the basis of future exposure in retrospective studies. We discuss the implications of these errors and propose some practical strategies to mitigate their impact. By raising awareness of these pitfalls, this paper aims to enhance the rigor and reproducibility of biostatistical analyses, thereby fostering more robust and reliable biomedical research findings.

Effect of severity and etiology of chronic kidney disease in patients with heart failure with mildly reduced ejection fraction

OBJECTIVE

The study investigates the prognostic impact of the severity and etiology of chronic kidney disease (CKD) in patients with heart failure with mildly reduced ejection fraction (HFmrEF).

BACKGROUND

Data regarding the outcomes in patients with CKD in HFmrEF is scarce.

METHODS

Consecutive patients with HFmrEF were retrospectively included at one institution from 2016 to 2022. Prognosis of patients with different stages and etiologies of CKD was investigated with regard to the primary endpoint of all-cause mortality at 30 months.

RESULTS

A total of 2155 consecutive patients with HFmrEF were included with an overall prevalence of CKD of 31%. Even milder stages of CKD (i.e., KDIGO stage 3a) were associated with an increased risk of 30-months all-cause mortality (HR = 1.242; 95% CI 1.147-1.346; p = 0.001). However, long-term prognosis did not differ in patients with KDIGO stage 5 compared to patients with stage 4 (HR = 0.886; 95% CI 0.616-1.275; p = 0.515). Furthermore, the highest risk of HF-related rehospitalization was observed in patients with KDIGO stages 3b and 4 (log rank p ≤ 0.015), whereas patients with KDIGO stage 5 had a lower risk of HF-related rehospitalization compared to patients with KDIGO stage 4 (HR = 0.440; 95% CI 0.228-0.849; p = 0.014). In contrast, the etiology of CKD was not associated with the risk of 30-month all-cause mortality (log rank p ≥ 0.347) and HF-related rehospitalization (log rank p ≥ 0.149).

CONCLUSION

In patients with HFmrEF, even milder stages of CKD were independently associated with increased risk of 30-months all-cause mortality.

Variations in Incidence and Prognosis of Stage 4 CKD Among Adults Identified Using Different Algorithms: A Population-Based Cohort Study

RATIONALE & OBJECTIVE

Clinical guidelines define chronic kidney disease (CKD) as abnormalities of kidney structure or function for>3 months. Assessment of the duration criterion may be implemented in different ways, potentially impacting estimates of disease incidence or prevalence in the population, individual diagnosis, and treatment decisions, especially for more severe cases. We investigated differences in incidence and prognosis of CKD stage G4 identified by 1 of 4 algorithms.

STUDY DESIGN

Population-based cohort study in Alberta, Canada.

SETTING & PARTICIPANTS

Residents>18 years old with incident CKD stage G4 (eGFR 15-29mL/min/1.73m2) diagnosed between April 1, 2015, and March 31, 2018, based on administrative and laboratory data.

EXPOSURE

Four outpatient eGFR-based algorithms, increasing in stringency, for defining cohorts with CKD G4 were evaluated: (1) a single test, (2) first eGFR<30mL/min/1.73m2 and a second eGFR 15-29mL/min/1.73m2 measured>90 days apart (2 tests), (3) ≥2 eGFR measurements of<30mL/min/1.73m2 sustained for>90 days (qualifying period) and the last eGFR in the qualifying period of 15-29mL/min/1.73m2 (relaxed sustained), and (4) ≥2 consecutive measurements of 15-29mL/min/1.73m2 for>90 days (rigorous sustained).

OUTCOME

Time to the earliest of death, eGFR improvement (a sustained increase in eGFR to≥30mL/min/1.73m2 for>90 days and>25% increase from the index eGFR), or kidney failure.

ANALYTICAL APPROACH

For each of the 4 cohorts, incidence rates and event-specific cumulative incidence functions at 1 year from cohort entry were estimated.

RESULTS

The incidence rates of CKD G4 decreased as algorithms became more stringent, from 190.7 (single test) to 79.9 (rigorous sustained) per 100,000 person-years. The 2 cohorts based on sustained reductions in eGFR were of comparable size and 1-year event-specific probabilities. The 2 cohorts based on a single test and a 2-test sequence were larger and experienced higher probabilities of eGFR improvement.

LIMITATIONS

A short follow-up period of 1 year and a predominantly White population.

CONCLUSIONS

The use of more stringent algorithms for defining CKD G4 results in substantially lower estimates of disease incidence, the identification of a group with a lower probability of eGFR improvement, and a higher risk of kidney failure. These findings can inform implementation decisions of disease definitions in clinical reporting systems and research studies.

PLAIN-LANGUAGE SUMMARY

Although guidelines recommend>3 months to define chronic kidney disease (CKD), the methods for defining specific stages, particularly G4 (eGFR 15-29mL/min/1.73m2) when referral to nephrology services is recommended, have been implemented differently across studies and surveillance programs. We studied differences in incidence and prognosis of CKD G4 cohorts identified by 4 algorithms using administrative and outpatient laboratory databases in Alberta, Canada. We found that, compared with a single-test definition, more stringent definitions resulted in a lower disease incidence and identified a group with worse short-term kidney outcomes. These findings highlight the impact of the choice of algorithm used to define CKD G4 on disease burden estimates at the population level, on individual prognosis, and on treatment/referral decisions.

Acute Kidney Injury Duration and 20-Year Risks of CKD and Cardiovascular Disease

Introduction

Acute kidney injury (AKI) is associated with chronic kidney disease (CKD) and cardiovascular disease (CVD); however, it is unclear whether AKI duration affects the long-term risks of CKD and CVD. Therefore, we performed a population-based cohort study examining the associations between AKI duration and CKD and CVD.

Methods

We identified patients with laboratory-recorded AKI in Denmark from 1990 through 2018. AKIs were categorized as rapid reversal AKI (≤48 hours), persistent AKI (2-7 days), and acute kidney disease (AKD) (>7 days). We estimated 20-year risks and adjusted hazard ratios (aHRs) of incident CKD and CVD.

Results

The study comprised 169,582 patients with AKI, with 100,478 and 76,838 included in the analysis of CKD and CVD, respectively. The 20-year risks of CKD were 26.3%, 29.5%, and 28.7% for rapid reversal AKI, persistent AKI, and AKD, respectively. Compared with rapid reversal AKI, aHRs were 1.13 (95% confidence interval [CI], 1.08-1.19) for persistent AKI and 1.36 (95% CI, 1.30-1.41) for AKD. Risks and rates of overall CVD were similar for rapid reversal AKI, persistent AKI, and AKD. However, persistent AKI was associated with a slightly increased aHR of heart failure (1.09; 95% CI, 1.02-1.16), and aHRs of heart failure, ischemic heart disease, and peripheral artery disease were slightly increased for AKD (1.09 [95% CI, 1.03-1.15], 1.11 [95% CI, 1.03-1.19], and 1.10 [95% CI, 1.02-1.17], respectively).

Conclusion

AKI duration was associated with development of CKD, but not overall CVD; however, rates of heart failure, ischemic heart disease, and peripheral artery disease increased slightly with AKI duration.

Association of Low Glomerular Filtration Rate With Adverse Outcomes at Older Age in a Large Population With Routinely Measured Cystatin C

BACKGROUND

The commonly accepted threshold of glomerular filtration rate (GFR) to define chronic kidney disease (CKD) is less than 60 mL/min/1.73 m2. This threshold is based partly on associations between estimated GFR (eGFR) and the frequency of adverse outcomes. The association is weaker in older adults, which has created disagreement about the appropriateness of the threshold for these persons. In addition, the studies measuring these associations included relatively few outcomes and estimated GFR on the basis of creatinine level (eGFRcr), which may be less accurate in older adults.

OBJECTIVE

To evaluate associations in older adults between eGFRcr versus eGFR based on creatinine and cystatin C levels (eGFRcr-cys) and 8 outcomes.

DESIGN

Population-based cohort study.

SETTING

Stockholm, Sweden, 2010 to 2019.

PARTICIPANTS

82 154 participants aged 65 years or older with outpatient creatinine and cystatin C testing.

MEASUREMENTS

Hazard ratios for all-cause mortality, cardiovascular mortality, and kidney failure with replacement therapy (KFRT); incidence rate ratios for recurrent hospitalizations, infection, myocardial infarction or stroke, heart failure, and acute kidney injury.

RESULTS

The associations between eGFRcr-cys and outcomes were monotonic, but most associations for eGFRcr were U-shaped. In addition, eGFRcr-cys was more strongly associated with outcomes than eGFRcr. For example, the adjusted hazard ratios for 60 versus 80 mL/min/1.73 m2 for all-cause mortality were 1.2 (95% CI, 1.1 to 1.3) for eGFRcr-cys and 1.0 (CI, 0.9 to 1.0) for eGFRcr, and for KFRT they were 2.6 (CI, 1.2 to 5.8) and 1.4 (CI, 0.7 to 2.8), respectively. Similar findings were observed in subgroups, including those with a urinary albumin-creatinine ratio below 30 mg/g.

LIMITATION

No GFR measurements.

CONCLUSION

Compared with low eGFRcr in older patients, low eGFRcr-cys was more strongly associated with adverse outcomes and the associations were more uniform.

PRIMARY FUNDING SOURCE

Swedish Research Council, National Institutes of Health, and Dutch Kidney Foundation.

A population-based cohort defined risk of hyperkalemia after initiating SGLT-2 inhibitors, GLP1 receptor agonists or DPP-4 inhibitors to patients with chronic kidney disease and type 2 diabetes

Hyperkalemia is a common adverse event in patients with chronic kidney disease (CKD) and type 2 diabetes and limits the use of guideline-recommended therapies such as renin-angiotensin system inhibitors. Here, we evaluated the comparative effects of sodium-glucose cotransporter-2 inhibitors (SGLT-2i), glucagon-like peptide-1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-4 inhibitors (DPP-4i) on the risk of hyperkalemia. We conducted a population-based active-comparator, new-user cohort study using claims data from Medicare and two large United States commercial insurance databases (April 2013-April 2022). People with CKD stages 3-4 and type 2 diabetes who newly initiated SGLT-2i vs. DPP-4i (141671 patients), GLP-1RA vs. DPP-4i (159545 patients) and SGLT-2i vs. GLP-1RA (93033 patients) were included. The primary outcome was hyperkalemia diagnosed in inpatient or outpatient settings. Secondary outcomes included hyperkalemia diagnosed in inpatient or emergency department setting, and serum potassium levels of 5.5 mmol/L or more. Pooled hazard ratios and rate differences were estimated after propensity score matching to adjust for over 140 potential confounders. Initiation of SGLT-2i was associated with a lower risk of hyperkalemia compared with DPP-4i (hazard ratio 0.74; 95% confidence interval 0.68-0.80) and contrasted to GLP-1RA (0.92; 0.86-0.99). Compared with DPP-4i, GLP-1RA were also associated with a lower risk of hyperkalemia (0.80; 0.75-0.86). Corresponding absolute rate differences/1000 person-years were -24.8 (95% confidence interval -31.8 to -17.7), -5.0 (-10.9 to 0.8), and -17.7 (-23.4 to -12.1), respectively. Similar findings were observed for the secondary outcomes, among subgroups, and across single agents within the SGLT-2i and GLP-1RA classes. Thus, SGLT-2i and GLP-1RA are associated with a lower risk of hyperkalemia than DPP-4i in patients with CKD and type 2 diabetes, further supporting the use of these drugs in this population.

Comparative Safety and Effectiveness of Warfarin or Rivaroxaban Versus Apixaban in Patients With Advanced CKD and Atrial Fibrillation: Nationwide US Cohort Study

RATIONALE & OBJECTIVE

Head-to-head data comparing the effectiveness and safety of oral anticoagulants in patients with atrial fibrillation (AF) and advanced chronic kidney disease (CKD) are lacking. We compared the safety and effectiveness of warfarin or rivaroxaban versus apixaban in patients with AF and non-dialysis-dependent CKD stage 4/5.

STUDY DESIGN

Propensity score-matched cohort study.

SETTING & PARTICIPANTS

2 nationwide US claims databases, Medicare and Optum's deidentified Clinformatics Data Mart Database, were searched for the interval from January 1, 2013, through March 31, 2022, for patients with nonvalvular AF and CKD stage 4/5 who initiated warfarin versus apixaban (matched cohort, n=12,488) and rivaroxaban versus apixaban (matched cohort, n = 5,720).

EXPOSURES

Warfarin, rivaroxaban, or apixaban.

OUTCOMES

Primary outcomes included major bleeding and ischemic stroke. Secondary outcomes included all-cause mortality, major gastrointestinal bleeding, and intracranial bleeding.

ANALYTICAL APPROACH

Cox regression was used to estimate HRs, and 1:1 propensity-score matching was used to adjust for 80 potential confounders.

RESULTS

Compared with apixaban, warfarin initiation was associated with a higher rate of major bleeding (HR, 1.85; 95% CI, 1.59-2.15), including major gastrointestinal bleeding (1.86; 1.53-2.25) and intracranial bleeding (2.15; 1.42-3.25). Compared with apixaban, rivaroxaban was also associated with a higher rate of major bleeding (1.69; 1.33-2.15). All-cause mortality was similar for warfarin (1.08; 0.98-1.18) and rivaroxaban (0.94; 0.81-1.10) versus apixaban. Furthermore, no statistically significant differences for ischemic stroke were observed for warfarin (1.14; 0.83-1.57) or rivaroxaban (0.71; 0.40-1.24) versus apixaban, but the CIs were wide. Similar results were observed for warfarin versus apixaban in the positive control cohort of patients with CKD stage 3, consistent with randomized trial findings.

LIMITATIONS

Few ischemic stroke events, potential residual confounding.

CONCLUSIONS

In patients with AF and advanced CKD, rivaroxaban and warfarin were associated with higher rates of major bleeding compared with apixaban, suggesting a superior safety profile for apixaban in this high-risk population.

PLAIN-LANGUAGE SUMMARY

Different anticoagulants have been shown to reduce the risk of stroke in patients with atrial fibrillation, such as warfarin and direct oral anticoagulants like apixaban and rivaroxaban. Unfortunately, the large-scale randomized trials that compared direct anticoagulants versus warfarin excluded patients with advanced chronic kidney disease. Therefore, the comparative safety and effectiveness of warfarin, apixaban, and rivaroxaban are uncertain in this population. In this study, we used administrative claims data from the United States to answer this question. We found that warfarin and rivaroxaban were associated with increased risks of major bleeding compared with apixaban. There were few stroke events, with no major differences among the 3 drugs in the risk of stroke. In conclusion, this study suggests that apixaban has a better safety profile than warfarin and rivaroxaban.

Comparative Safety of Antidepressants in Adults with CKD

BACKGROUND

Depression is prevalent in patients with CKD and is related to poor prognosis. Despite the widespread use of antidepressants in the CKD population, their safety remains unclear.

METHODS

We identified adults with CKD stages G3-5 (eGFR <60 ml/min per 1.73 m 2 not treated with dialysis) and incident depression diagnosis during 2007-2019 from the Stockholm Creatinine Measurements project. Using the target trial emulation framework, we compared the following treatment strategies: ( 1 ) initiating versus not initiating antidepressants, ( 2 ) initiating mirtazapine versus selective serotonin reuptake inhibitors (SSRIs), and ( 3 ) initiating SSRIs with a lower dose versus a standard dose.

RESULTS

Of 7798 eligible individuals, 5743 (74%) initiated antidepressant treatment. Compared with noninitiation, initiation of antidepressants was associated with higher hazards of short-term outcomes, including hip fracture (hazard ratio [HR], 1.23; 95% confidence interval [CI], 0.88 to 1.74) and upper gastrointestinal bleeding (HR, 1.38; 95% CI, 0.82 to 2.31), although not statistically significant. Initiation of antidepressants was not associated with long-term outcomes, including all-cause mortality, major adverse cardiovascular event, CKD progression, and suicidal behavior. Compared with SSRIs, initiation of mirtazapine was associated with a lower hazard of upper gastrointestinal bleeding (HR, 0.52; 95% CI, 0.29 to 0.96), but a higher hazard of mortality (HR, 1.11; 95% CI, 1.00 to 1.22). Compared with the standard dose, initiation of SSRIs with a lower dose was associated with nonstatistically significantly lower hazards of upper gastrointestinal bleeding (HR, 0.68; 95% CI, 0.35 to 1.34) and CKD progression (HR, 0.80; 95% CI, 0.63 to 1.02), but a higher hazard of cardiac arrest (HR, 2.34; 95% CI, 1.02 to 5.40).

CONCLUSIONS

Antidepressant treatment was associated with short-term adverse outcomes but not long-term outcomes in people with CKD and depression.

Oral anticoagulant treatment and risk of kidney disease-a nationwide, population-based cohort study

Background

Direct oral anticoagulants (DOACs) are recommended as first-line treatment of atrial fibrillation. Whether DOAC use is associated with lower risks of kidney complications compared with vitamin K antagonists (VKAs) remains unclear. We examined this association in a nationwide, population-based cohort study.

Methods

We conducted a cohort study including patients initiating oral anticoagulant treatment within 3 months after an atrial fibrillation diagnosis in Denmark during 2012-18. Using routinely collected creatinine measurements from laboratory databases, we followed patients in an intention-to-treat approach for acute kidney injury (AKI) and chronic kidney disease (CKD) progression. We used propensity-score weighting to balance baseline confounders, computed weighted risks and weighted hazard ratios (HRs) with 95% confidence intervals (CIs) comparing DOACs with VKAs. We performed several subgroup analyses and a per-protocol analysis.

Results

We included 32 781 persons with atrial fibrillation initiating oral anticoagulation (77% initiating DOACs). The median age was 75 years, 25% had a baseline estimated glomerular filtration rate <60 mL/min/1.73 m2, and median follow-up was 2.3 (interquartile range 1.1-3.9) years. The weighted 1-year risks of AKI were 13.6% in DOAC users and 15.0% in VKA users (HR 0.86, 95% CI 0.82; 0.91). The weighted 5-year risks of CKD progression were 13.9% in DOAC users and 15.4% in VKA users (HR 0.85, 95% CI 0.79; 0.92). Results were similar across subgroups and in the per-protocol analysis.

Conclusions

Initiation of DOACs was associated with a decreased risk of AKI and CKD progression compared with VKAs. Despite the potential limitations of observational studies, our findings support the need for increased clinical awareness to prevent kidney complications among patients who initiate oral anticoagulants.

Absolute and Relative Risks of Kidney and Urological Complications in Patients With Inflammatory Bowel Disease

INTRODUCTION

The burden of kidney and urological complications in patients with inflammatory bowel disease (IBD) remains poorly characterized.

METHODS

We analyzed association between developing IBD (as a time-varying exposure) and relative risks of receiving diagnoses of chronic kidney disease (CKD), acute kidney injury (AKI), or kidney stones, and experiencing a clinically-relevant decline in estimated glomerular filtration rate (eGFR) (CKD progression; composite of kidney failure or an eGFR decline ≥30%) in 1,682,795 individuals seeking healthcare in Stockholm, Sweden, during 2006-2018. We quantified 5- and 10-year absolute risks of these complications in a parallel matched cohort of IBD cases and random controls matched (1:5) on sex, age, and eGFR.

RESULTS

During median 9 years, 10,117 participants developed IBD. Incident IBD was associated with higher risks of kidney-related complications compared with non-IBD periods: hazard ratio (HR) (95% confidence interval) was 1.24 (1.10-1.40) for receiving a CKD diagnosis and 1.11 (1.00-1.24) for CKD progression. For absolute risks, 11.8% IBD cases had a CKD event within 10-year. Of these, 6.4% received a CKD diagnosis, and 7.9% reached CKD progression. The risks of AKI (HR 1.97 [1.70-2.29]; 10-year absolute risk 3.6%) and kidney stones (HR 1.69 [1.48-1.93]; 10-year absolute risk 5.6%) were also elevated. Risks were similar in Crohn's disease and ulcerative colitis.

DISCUSSION

More than 10% of patients with IBD developed CKD within 10-year from diagnosis, with many not being identified through diagnostic codes. This, together with their elevated AKI and kidney stone risks, highlights the need of established protocols for kidney function monitoring and referral to nephrological/urological care for patients with IBD.

Acute kidney injury associated with nephrotoxic drugs in critically ill patients: a multicenter cohort study using electronic health record data

Background

Nephrotoxic drugs frequently cause acute kidney injury (AKI) in adult intensive care unit (ICU) patients. However, there is a lack of large pharmaco-epidemiological studies investigating the associations between drugs and AKI. Importantly, AKI risk factors may also be indications or contraindications for drugs and thereby confound the associations. Here, we aimed to estimate the associations between commonly administered (potentially) nephrotoxic drug groups and AKI in adult ICU patients whilst adjusting for confounding.

Methods

In this multicenter retrospective observational study, we included adult ICU admissions to 13 Dutch ICUs. We measured exposure to 44 predefined (potentially) nephrotoxic drug groups. The outcome was AKI during ICU admission. The association between each drug group and AKI was estimated using etiological cause-specific Cox proportional hazard models and adjusted for confounding. To facilitate an (independent) informed assessment of residual confounding, we manually identified drug group-specific confounders using a large drug knowledge database and existing literature.

Results

We included 92 616 ICU admissions, of which 13 492 developed AKI (15%). We found 14 drug groups to be associated with a higher hazard of AKI after adjustment for confounding. These groups included established (e.g. aminoglycosides), less well established (e.g. opioids) and controversial (e.g. sympathomimetics with α- and β-effect) drugs.

Conclusions

The results confirm existing insights and provide new ones regarding drug associated AKI in adult ICU patients. These insights warrant caution and extra monitoring when prescribing nephrotoxic drugs in the ICU and indicate which drug groups require further investigation.

Leisure-Time Physical Activity and Risk of Microvascular Complications in Individuals With Type 2 Diabetes: A UK Biobank Study

OBJECTIVE

The aim of this study was to determine dose-response associations, including the minimal effective level, between leisure-time physical activity and risk of incident neuropathy, nephropathy, and retinopathy.

RESEARCH DESIGN AND METHODS

This cohort study included 18,092 individuals with type 2 diabetes from the UK Biobank. Self-reported leisure-time physical activity was converted into MET-hours per week. Participants were categorized into no physical activity (0 MET-h/week), below recommendations (0-7.49 MET-h/week), at recommendations (7.5-14.9 MET-h/week), and above recommendations (≥15 MET-h/week). Microvascular complications were identified from hospital inpatient records using diagnosis codes. We used Cox proportional hazards regression analysis to calculate adjusted hazard ratios (aHRs) and restricted cubic splines to identify the minimal effective level of physical activity.

RESULTS

During a median follow-up of 12.1 years, 672 individuals (3.7%) were diagnosed with neuropathy, 1,839 (10.2%) with nephropathy, and 2,099 (11.7%) with retinopathy. Any level of physical activity was associated with a lower risk of neuropathy and nephropathy but not retinopathy. Compared with those reporting no physical activity, the aHR of neuropathy was 0.71 (95% CI 0.53, 0.90) below recommendations, 0.73 (0.56, 0.96) at recommendations, and 0.67 (0.52, 0.87) above recommendations. Corresponding aHRs for nephropathy were 0.79 (0.68, 0.92), 0.80 (0.67, 0.95), and 0.80 (0.68, 0.95). The association with retinopathy was weaker, with aHRs of 0.91 (0.78, 1.06), 0.91 (0.77, 1.08), and 0.98 (0.84, 1.15), respectively.

CONCLUSIONS

Any level of leisure-time physical activity was associated with a lower risk of neuropathy and nephropathy but not retinopathy in individuals with type 2 diabetes. For both neuropathy and nephropathy, the minimal effective physical activity level may correspond to <1.5 h of walking per week.

A nationwide cohort study comparing the effectiveness of diuretics and calcium channel blockers on top of renin-angiotensin system inhibitors on chronic kidney disease progression and mortality

It is unknown whether initiating diuretics on top of renin-angiotensin system inhibitors (RASi) is superior to alternative antihypertensive agents such as calcium channel blockers (CCBs) in patients with chronic kidney disease (CKD). For this purpose, we emulated a target trial in the Swedish Renal Registry 2007-2022 that included nephrologist-referred patients with moderate-advanced CKD and treated with RASi, who initiated diuretics or CCB. Using propensity score-weighted cause-specific Cox regression, we compared risks of major adverse kidney events (MAKE; composite of kidney replacement therapy [KRT], experiencing over a 40% eGFR decline from baseline, or an eGFR under 15 ml/min per 1.73m2), major cardiovascular events (MACE; composite of cardiovascular death, myocardial infarction or stroke), and all-cause mortality. We identified 5875 patients (median age 71 years, 64% men, median eGFR 26 ml/min per 1.73m2), of whom 3165 started a diuretic and 2710 a CCB. After a median follow-up of 6.3 years, 2558 MAKE, 1178 MACE and 2299 deaths occurred. Compared to CCB, diuretic use was associated with a lower risk of MAKE (weighted hazard ratio 0.87 [95% confidence interval: 0.77-0.97]), consistent across single components (KRT: 0.77 [0.66-0.88], over 40% eGFR decline: 0.80 [0.71-0.91] and eGFR under 15ml/min/1.73m2: 0.84 [0.74-0.96]). The risks of MACE (1.14 [0.96-1.36]) and all-cause mortality (1.07 [0.94-1.23]) did not differ between therapies. Results were consistent when modeling the total time drug exposure, across sub-groups and a broad range of sensitivity analyses. Thus, our observational study suggests that in patients with advanced CKD, using a diuretic rather than a CCB on top of RASi may improve kidney outcomes without compromising cardioprotection.

Prevalence of chronic kidney disease in women of reproductive age and observed birth rates

INTRODUCTION

Women of reproductive age with chronic kidney disease (CKD) are recognised to have decreased fertility and a higher risk of adverse pregnancy outcomes. How often CKD afflicts women of reproductive age is not well known. This study aimed to evaluate the burden of CKD and associated birth rates in an entire region.

METHODS

This was a retrospective cohort study including women of childbearing age in Stockholm during 2006-2015. We estimated the prevalence of "probable CKD" by the presence of an ICD-10 diagnosis of CKD, a single estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 or history of maintenance dialysis. By linkage with the Swedish Medical Birth Register we identified births during the subsequent three years from study inclusion and evaluated birth rates.

RESULTS

We identified 817,730 women in our region, of whom 55% had at least one creatinine measurement. A total of 3938 women were identified as having probable CKD, providing an age-averaged CKD prevalence of 0.50%. Women with probable CKD showed a lower birth rate 3 years after the index date (35.7 children per 1000 person years) than the remaining women free from CKD (46.5 children per 1000 person years).

CONCLUSION

As many as 0.50% of individuals in this cohort had probable CKD, defined on the basis of at least one eGFR<60 ml/min1.73 m2 test result, dialysis treatment (i.e. CKD stages 3-5) or an ICD-10 diagnosis of CKD. This prevalence is lower than previous estimates. Women with probable CKD, according to a study mainly capturing CKD 3-5, had a lower birth rate than those without CKD, illustrating the challenges of this population to successfully conceive.

Factors associated with incidence of acute kidney injury: a Japanese regional population-based cohort study, the Shizuoka study

BACKGROUND

Acute kidney injury (AKI) is a globally critical issue. Most studies about AKI have been conducted in limited settings on perioperative or critically ill patients. As a result, there is little information about the epidemiology and risk factors of AKI in the general population.

METHODS

We conducted a population-based cohort study using the Shizuoka Kokuho Database. We included subjects with records of health checkup results. The observation period for each participant was defined as from the date of insurance enrollment or April 2012, whichever occurred later, until the date of insurance withdrawal or September 2020, whichever was later. Primary outcome was AKI associated with admission based on the ICD-10 code. We described the incidence of AKI and performed a multivariate analysis using potential risk factors selected from comorbidities, medications, and health checkup results.

RESULTS

Of 627,814 subjects, 8044 were diagnosed with AKI (incidence 251 per 100,000 person-years). The AKI group was older, with more males. Most comorbidities and prescribed medications were more common in the AKI group. As novel factors, statins (hazard ratio (HR) 0.84, 95% confidence interval (CI) 0.80-0.89) and physical activity habits (HR 0.79, 95% CI 0.75-0.83) were associated with reduced incidence of AKI. Other variables associated with AKI were approximately consistent with those from previous studies.

CONCLUSIONS

The factors associated with AKI and the incidence of AKI in the general Japanese population are indicated. This study generates the hypothesis that statins and physical activity habits are novel protective factors for AKI.

Factors associated with COVID-19 vaccine uptake in people with kidney disease: an OpenSAFELY cohort study

OBJECTIVE

To characterise factors associated with COVID-19 vaccine uptake among people with kidney disease in England.

DESIGN

Retrospective cohort study using the OpenSAFELY-TPP platform, performed with the approval of NHS England.

SETTING

Individual-level routine clinical data from 24 million people across GPs in England using TPP software. Primary care data were linked directly with COVID-19 vaccine records up to 31 August 2022 and with renal replacement therapy (RRT) status via the UK Renal Registry (UKRR).

PARTICIPANTS

A cohort of adults with stage 3-5 chronic kidney disease (CKD) or receiving RRT at the start of the COVID-19 vaccine roll-out was identified based on evidence of reduced estimated glomerular filtration rate (eGFR) or inclusion in the UKRR.

MAIN OUTCOME MEASURES

Dose-specific vaccine coverage over time was determined from 1 December 2020 to 31 August 2022. Individual-level factors associated with receipt of a 3-dose or 4-dose vaccine series were explored via Cox proportional hazards models.

RESULTS

992 205 people with stage 3-5 CKD or receiving RRT were included. Cumulative vaccine coverage as of 31 August 2022 was 97.5%, 97.0% and 93.9% for doses 1, 2 and 3, respectively, and 81.9% for dose 4 among individuals with one or more indications for eligibility. Delayed 3-dose vaccine uptake was associated with younger age, minority ethnicity, social deprivation and severe mental illness-associations that were consistent across CKD severity subgroups, dialysis patients and kidney transplant recipients. Similar associations were observed for 4-dose uptake.

CONCLUSION

Although high primary vaccine and booster dose coverage has been achieved among people with kidney disease in England, key disparities in vaccine uptake remain across clinical and demographic groups and 4-dose coverage is suboptimal. Targeted interventions are needed to identify barriers to vaccine uptake among under-vaccinated subgroups identified in the present study.