AKI is an important complication of abdominal surgery. In addition to sex, hypertension, and chronic kidney disease, ASA physical status classification is an independent predictor of AKI. Individuals who develop AKI have substantially worse short-term outcomes, including higher 30-day mortality, even after correcting for multiple patient- and procedure-related risk factors.

The number of patients prescribed long-term opioids and benzodiazepines and complications from their long-term use have increased. Information regarding the perioperative outcomes of patients prescribed these medications before surgery is limited.OBJECTIVE To determine whether patients prescribed opioids and/or benzodiazepines within 6 months preoperatively would have greater short-and long-term mortality and increased opioid consumption postoperatively. DESIGN, SETTING, AND PARTICIPANTSThis retrospective, single-center, population-based cohort study included all patients 18 years or older, undergoing noncardiac surgical procedures at a national hospital in Iceland from December 12, 2005, to December 31, 2015, with follow-up through May 20, 2016. A propensity score-matched control cohort was generated using individuals from the group that received prescriptions for neither medication class within 6 months preoperatively. Data analysis was performed from April 10, 2018, to March 9, 2019.EXPOSURES Patients who filled prescriptions for opioids only, benzodiazepines only, both opioids and benzodiazepines, or neither medication within 6 months preoperatively. MAIN OUTCOMES AND MEASURESLong-term survival compared with propensity score-matched controls. Secondary outcomes were 30-day survival and persistent postoperative opioid consumption, defined as a prescription filled more than 3 months postoperatively. RESULTS Among 41 170 noncardiac surgical cases in 27 787 individuals (16 004 women [57.6%]; mean [SD] age, 56.3 [18.8] years), a preoperative prescription for opioids only was filled for 7460 cases (17.7%), benzodiazepines only for 3121 (7.4%), and both for 2633 (6.2%). Patients who filled preoperative prescriptions for either medication class had a greater comorbidity burden compared with patients receiving neither medication class (Elixhauser comorbidity index >0 for 16% of patients filling prescriptions for opioids only, 22% for benzodiazepines only, and 21% for both medications compared with 14% for patients filling neither). There was no difference in 30-day (opioids only: 1.3% vs 1.0%; P = .23; benzodiazepines only: 1.9% vs 1.5%; P = .32) or long-term (opioids only: hazard ratio [HR], 1.12 [95% CI, 1.01-1.24]; P = .03; benzodiazepines only: HR, 1.11 [95% CI, 0.98-1.26]; P = .11) survival among the patients receiving opioids or benzodiazepines only compared with controls. However, patients prescribed both opioids and benzodiazepines had greater 30-day mortality (3.2% vs 1.8%; P = .004) and a greater hazard of long-term mortality (HR, 1.41; 95% CI, 1.22-1.64; P < .001). The rate of persistent postoperative opioid consumption was higher for patients filling prescriptions for opioids only (43%), benzodiazepines only (23%), or both (66%) compared with patients filling neither (12%) (P < .001 for all). CONCLUSIONS AND RELEVANCEThe findings suggest that opioid and benzodiazepine prescription fills in the 6 months before surgery are associated with increased short-and long-term mortality and an increased rate of pers...

Serum free light chain (FLC) concentration is greatly affected by kidney function. Using a large prospective population-based cohort, we aimed to establish a reference interval for FLCs in persons with chronic kidney disease (CKD). A total of 75422 participants of the iStopMM study were screened with serum FLC, serum protein electrophoresis and immunofixation. Estimated glomerular filtration rate (eGFR) was calculated from serum creatinine. Central 99% reference intervals were determined, and 95% confidence intervals calculated. Included were 6461 (12%) participants with measured FLCs, eGFR < 60 mL/min/1.73 m2, not receiving renal replacement therapy, and without evidence of monoclonality. Using current reference intervals, 60% and 21% had kappa and lambda FLC values outside the normal range. The FLC ratio was outside standard reference interval (0.26–1.65) in 9% of participants and outside current kidney reference interval (0.37–3.10) in 0.7%. New reference intervals for FLC and FLC ratio were established. New reference intervals for the FLC ratio were 0.46–2.62, 0.48–3.38, and 0.54–3.30 for eGFR 45–59, 30–44, and < 30 mL/min/1.73 m2 groups, respectively. The crude prevalence of LC-MGUS in CKD patients was 0.5%. We conclude that current reference intervals for FLC and FLC ratio are inaccurate in CKD patients and propose new eGFR based reference intervals to be implemented.