Acute kidney injury in statin initiators

Effects of statins on the incidence and outcomes of acute kidney injury in critically ill patients: a systematic review and meta-analysis

INTRODUCTION

In critically ill patients, acute kidney injury (AKI) is a common complication with very high mortality rates. Several studies indicated that statin therapy, primarily due to its so-called pleiotropic effects, may beneficially affect the course of the disease, otherwise leading to significant clinical complications. However, both the original research as well as available meta-analyses on these associations report equivocal results. This leaves open a question whether pre- and perioperative statins might prevent AKI and improve overall prognosis in patients undergoing surgery.

MATERIAL AND METHODS

Following a systematic search of the literature, we performed a meta-analysis of selected clinical studies investigating the impact of statin treatment on the development and the clinical outcomes of AKI among subjects undergoing surgeries. The pooled odds ratios (OR) with 95% confidence intervals (CI) for the development of AKI and AKI-associated mortality, as well as the pooled mean differences (MD) and 95% CI for mean intensive care unit (ICU) stay and overall hospital length of stay were calculated for statin users compared to non-users.

RESULTS

Our results showed a highly significant association between statin use and the decrease in mortality of patients with AKI (OR = 0.73, 95% CI: 0.69-0.77; p<0.001). The development of AKI (OR = 0.92, 95% CI: 0.63-1.33; p = 0.659) as well as the ICU stay (MD = -0.02, 95% CI: -0.06 - 0.02; p = 0.321) were not significantly affected, while the overall hospital length of stay (MD = -0.49, 95% CI: -0.91 -0.07; p = 0.020) was reduced. Subgroup analysis showed that both pre- and postoperative statin use were not associated with the risk of AKI.

CONCLUSIONS

Our analysis showed a significant association between statin therapy and overall mortality of critically ill surgical patients diagnosed with AKI, while at the same time the use of statins did not affect the length of their stay in ICU.

Influence of statin-potency on the risk of kidney disease - A nationwide cohort study using laboratory data

PURPOSE

To estimate the risk of kidney disease in high-potency statin users compared to those treated with low-potency statins without history of kidney disease at statin initiation, linking the Swedish national healthcare registers and laboratory data.

METHODS

Incident users of statins, ≥40 years of age, with estimated Glomerular Filtration Rate (eGFR) >60 ml/min/1.73 m² and no diagnosis of kidney disease at treatment initiation were identified between 2006 and 2007 and then followed for 2-years. The outcome was the incidence of kidney disease identified by the presence of the diagnostic code in the healthcare registers or eGFR <60 ml/min/1.73 m² . We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) with adjusted and propensity score (PS)-matched Cox proportional hazards models.

RESULTS

A total of 27 385 patients were identified, 25.2% of which treated with a high-potency statin. During the follow-up, 68 (0.25%) patients were identified with a diagnosis of kidney disease from the registers. The number increased to 2498 (9.1%) when the criteria of eGFR <60 ml/min/1.73 m² was added. The adjusted HR of kidney disease in high-potency statin users was 1.14 (95%CI 1.03-1.25) compared to low-potency users; the result was unchanged after the PS approach.

CONCLUSIONS

Adding information from laboratory data to those from the national health registers, a slightly increased risk for kidney disease was found in high-potency statin users without pre-existing kidney disease at treatment initiation compared to those treated with low-potency statins.

Statin use and the risk of acute kidney injury in older adults

BACKGROUND

As more patients at lower cardiovascular (CV) risk are treated with statins, the balance between cardiovascular benefits and the risk of adverse events becomes increasingly important.

METHODS

We did a population-based cohort study (May 1, 2002 to March 30, 2013) using province-wide laboratory and administrative data in Alberta. We studied new statin users aged 66 years of age and older who were not receiving renal replacement therapy at baseline. We assessed statin use at 30-day intervals to allow time-varying assessment of statin exposure in Cox proportional hazards models that examined the relation between statin use and hospitalization with acute kidney injury (AKI).

RESULTS

Of the 128,140 new statin users, 47 and 46% were prescribed high- and medium-intensity regimens at the index date. During median follow-up of 4.6 years (interquartile range 2.2, 7.4), 9118 individuals were hospitalized for AKI. Compared to non-use, the use of high- and medium-intensity statin regimens was associated with significant increases in the adjusted risks of hospitalization with AKI: hazard ratios 1.16 [95% confidence interval (CI) 1.10, 1.23] and 1.07 (95% CI 1.01, 1.13), respectively. Risks of AKI were higher among women than men, and among users of angiotensin converting enzyme inhibitors/angiotensin receptor blockers than non-users, and among diuretic users (p for interaction 0.002, 0.01, and 0.04 respectively).

CONCLUSIONS

We found a graded, independent association between the intensity of statin use and the risk of hospitalization with AKI, although the absolute magnitude of the excess risk was small.

Antimuscarinic use and discontinuation in an older adult population

INTRODUCTION

Although antimuscarinics are typically the first-line pharmacological treatment option for overactive bladder, patients often discontinue therapy. The aim of this research project is to identify the rate of antimuscarinic discontinuation, switching, and continuation and differences in discontinuation among different antimuscarinics.

METHODS

Using the 5% random sample of Medicare Claims Data, we identified a cohort of patients aged ≥ 66 years old who newly initiated antimuscarinics between January 1, 2007 and December 31, 2012. Treatment discontinuation was defined as no subsequent fills of the initial antimuscarinic in the days' supply plus a 30 day grace period. We ascertained percentages of patients who discontinued antimuscarinics, switched antimuscarinics, or died within 12 months of antimuscarinic initiation. Cox proportional hazards models were used to determine time to discontinuation of individual antimuscarinics relative to oxybutynin immediate-release (IR).

RESULTS

Among the 42,886 new-users of antimuscarinics, 71.8% discontinued, 10.8% switched, and 3.2% died prior to antimuscarinic discontinuation or switching while only 14.2% continually filled an antimuscarinic for one year. In the multivariable analysis, patients who were initiated on oxybutynin extended-released (ER), tolterodine, trospium, darifenacin, solifenacin, and fesoterodine were significantly less likely to be discontinued therapy compared to oxybutynin IR (p < 0.001).

CONCLUSION

After one year of antimuscarinic initiation, only 14% of older adult patients continuously utilized their initial antimuscarinic therapy suggesting a need for clinical interventions to improve continual use of antimuscarinics.

Observational Research Using Propensity Scores

In most observational studies, treatments or other "exposures" (in an epidemiologic sense) do not occur at random. Instead, treatments or other such interventions depend on several patient-related and patient-independent characteristics. Such factors, associated with the receipt vs nonreceipt of treatment, may also be-independently-associated with outcomes. Thus, confounding exists making it difficult to ascertain the true association between treatments and outcomes. Propensity scores (PS) represent an intuitive set of approaches to reduce the influence of such "confounding" factors. PS is a computed probability of treatment, a value that is estimated for each patient in an observational study and then applied (in a variety of ways such as matching, stratification, weighting, etc.) to reduce distortion in the true nature of the association between treatment (or any similar exposure) and outcomes. Despite several advantages, PS-based methods cannot account for unmeasured confounding, ie, for factors that are not being included in the computation of PS.

Predictors of prevalent statin use among older adults identified as statin initiators based on Medicare claims data

PURPOSE

Few studies have evaluated the degree to which prescription drug initiators are correctly identified using claims data. We examine the prevalence and predictors of recent statin possession in statin initiators identified using claims data.

METHODS

Among Medicare Current Beneficiary Survey (MCBS) respondents, we used Medicare Part D claims from 2006 to 2011 to identify statin initiators using a 12-month baseline period of no prior statin claims. Using MCBS interview data, we identified those with self-reported statins obtained during the baseline period. We used log-binomial regression to estimate adjusted prevalence ratios (adjPR) and 95% confidence intervals (CI) for predictors of recent statin possession.

RESULTS

Among 766 statin initiators identified in prescription claims, 155 (20%) reported recent statin possession during baseline. Beneficiaries with no Part D claims in the past 30 days (adjPR = 1.49, 95%CI: 1.13, 1.96), those with no inpatient, outpatient or physician visits in the past 30 days (adjPR = 1.50, 95%CI: 1.11, 2.03), those with a brand name statin index claim (adjPR = 1.55, 95%CI: 1.19, 2.02), and those with an index claim in January or February (adjPR = 1.50, 95%CI: 1.00, 2.26) had an increased probability of recent statin possession.

CONCLUSIONS

In a cohort of statin initiators identified using prescription claims, 20% had evidence of statin possession during the baseline period. Pharmacoepidemiologic new user studies may benefit from including sensitivity analyses within subgroups less likely to include prevalent users to assess the robustness of key findings to misidentification of the time of treatment initiation. Copyright © 2016 John Wiley & Sons, Ltd.

Comparative effectiveness research and its utility in In-clinic practice

One of the important components of patient-centered healthcare is comparative effectiveness research (CER), which aims at generating evidence from the real-life setting. The primary purpose of CER is to provide comparative information to the healthcare providers, patients, and policy makers about the standard of care available. This involves research on clinical questions unanswered by the explanatory trials during the regulatory approval process. Main methods of CER involve randomized controlled trials and observational methods. The limitations of these two methods have been overcome with the help of new statistical methods. After the evidence generation, it is equally important to communicate the results to all the interested organizations. CER is beginning to have its impact in the clinical practice as its results become part of the clinical practice guidelines. CER will have far-reaching scientific and financial impact. CER will make both the treating physician and the patient equally responsible for the treatment offered.

Hypernatremia is a significant risk factor for acute kidney injury after subarachnoid hemorrhage: a retrospective analysis

BACKGROUND

Hypertonic saline therapy is often used in critically ill subarachnoid hemorrhage (SAH) patients for indications ranging from control of intracranial hypertension to managing symptomatic hyponatremia. The risk factors for developing acute kidney injury (AKI) in this patient population are not well defined.

SPECIFIC AIM

To study the role of serum sodium in developing AKI (based on the AKIN definition) in the SAH population admitted to a large academic neurocritical care unit.

METHODS

This is an IRB-approved, retrospective cohort study of patients admitted to a tertiary neuro intensive care unit. We included adult (age ≥ 18 years) SAH patients admitted to the neuro intensive care unit for at least 72 h. Development of AKI after admission to the ICU was defined using the AKIN serum creatinine criteria between 72 h and 14 days following admission. A Cox proportional hazards survival model with multiple time varying covariates was developed to evaluate the effect of maximum sodium exposure on the risk of AKI. Sodium exposure was captured as the running maximum of daily maximum serum sodium concentration (mEq/L). Sodium exposure was used as a surrogate for hypertonic saline therapy.

RESULTS

The final cohort of patients included 736 patients admitted to the neuro intensive care unit between 2006 and 2012. The number of patients who developed AKI was 64 (9 %). These patients had an increased length of stay (15.6 ± 9.4 vs. 12.5 ± 8.7 days). The odds of death were more than two fold greater among patients who developed AKI (odds ratio 2.33 95 % CI 1.27, 4.3). Sodium exposure was significantly associated with the hazard of developing AKI, adjusting for age, sex, preexisting renal disease, diabetes mellitus, radiocontrast exposure, number of days on mechanical ventilation, and admission Glasgow Coma Scale score. For each 1 mEq/L increase in the running maximum daily serum sodium, the hazard of developing AKI was increased by 5.4 % (95 % CI 1.4, 9.7).

CONCLUSION

The maximum daily sodium is a significant risk factor for developing AKI in patients with SAH.

Short look-back periods in pharmacoepidemiologic studies of new users of antibiotics and asthma medications introduce severe misclassification

PURPOSE

The aim of this study was to quantify the effect of the look back period on the misclassification of new users of antibiotics and asthma medications.

METHODS

We included all children born in Denmark from 1995 through 2006 and all prescriptions of antibiotics and asthma medication from 1995 through 2011. The study period was 2007 through 2011. True new users redeemed their first prescription in the study period whereas prior users redeemed their first prescription before the study period. Look-back periods ranged from 30 days up to 12 years prior to the study period, and we defined new users as those without a prescription in the look-back period. The relative misclassification (RM) was estimated as the number of defined new users divided by the number of true new users.

RESULTS

For antibiotics, the RM decreased from 4.75 for look-back periods of 30 days to 2.36 for 2 years and 1.33 for 5 years. For asthma medication, the RM decreased from 2.53 for look-back periods of 30 days to 1.48 for 2 years and 1.20 for 5 years. Older age, male gender, and absence of treatment-related diagnoses were associated with higher RM.

CONCLUSIONS

Studies applying the new user design are strongly dependent on the available information on prescriptions. For drug classes with intermittent use such as asthma medications, even a 2-year look-back period produced severe misclassification. Excluding children with a prior treatment-related diagnosis can reduce the level of misclassification.