Characterization of hospital airborne SARS-CoV-2.

BACKGROUND: The mechanism for spread of SARS-CoV-2 has been attributed to large particles produced by coughing and sneezing. There is controversy whether smaller airborne particles may transport SARS-CoV-2. Smaller particles, particularly fine particulate matter (≤ 2.5 µm in diameter), can remain airborne for longer periods than larger particles and after inhalation will penetrate deeply into the lungs. Little is known about the size distribution and location of airborne SARS-CoV-2 RNA. METHODS: As a measure of hospital-related exposure, air samples of three particle sizes (> 10.0 µm, 10.0-2.5 µm, and ≤ 2.5 µm) were collected in a Boston, Massachusetts (USA) hospital from April to May 2020 (N = 90 size-fractionated samples). Locations included outside negative-pressure COVID-19 wards, a hospital ward not directly involved in COVID-19 patient care, and the emergency department. RESULTS: SARS-CoV-2 RNA was present in 9% of samples and in all size fractions at concentrations of 5 to 51 copies m-3. Locations outside COVID-19 wards had the fewest positive samples. A non-COVID-19 ward had the highest number of positive samples, likely reflecting staff congregation. The probability of a positive sample was positively associated (r = 0.95, p < 0.01) with the number of COVID-19 patients in the hospital. The number of COVID-19 patients in the hospital was positively associated (r = 0.99, p < 0.01) with the number of new daily cases in Massachusetts. CONCLUSIONS: More frequent detection of positive samples in non-COVID-19 than COVID-19 hospital areas indicates effectiveness of COVID-ward hospital controls in controlling air concentrations and suggests the potential for disease spread in areas without the strictest precautions. The positive associations regarding the probability of a positive sample, COVID-19 cases in the hospital, and cases in Massachusetts suggests that hospital air sample positivity was related to community burden. SARS-CoV-2 RNA with fine particulate matter supports the possibility of airborne transmission over distances greater than six feet. The findings support guidelines that limit exposure to airborne particles including fine particles capable of longer distance transport and greater lung penetration.

Pilot trial of a transdiagnostic computerized anxiety sensitivity intervention among VA primary care patients.

People in need of mental health treatment do not access care at high rates or in a timely manner, inclusive of Veterans at Department of Veteran's Affairs (VA) medical centers. Barriers to care have been identified, and one potential solution is the use of technology-based interventions within primary care. This study evaluated the Cognitive Anxiety Sensitivity Treatment (CAST), a previously developed computerized treatment that has shown efficacy in community samples for mental health symptoms including: anxiety, depression, post-traumatic stress, and suicidal ideation. VA primary care patients with elevated anxiety sensitivity (N = 25) were recruited to participate in a mixed-method open pilot to examine acceptability, usability, and preliminary effectiveness in a VA primary care setting. Participants completed an initial visit, that included the intervention, and a one-month follow-up. Veterans found CAST to be generally acceptable, with strong usability ratings. Qualitative analyses identified areas of strength and areas for improvement for use with VA primary care Veterans. Repeated measures ANCOVAs revealed significant effects for symptoms of anxiety, depression, traumatic-stress, and suicidal ideation. CAST could potentially have a large public health impact if deployed across VA medical centers as a first-step intervention for a range of mental health presenting concerns.

Outcomes and Trends in Colorectal Surgery in U.S. Veterans: A 10-year Experience at a Tertiary Veterans Affairs Medical Center.

Introduction: The past decade has witnessed numerous advances in colorectal surgery secondary to minimally invasive surgery, evidence-based enhanced recovery programs, and a growing emphasis on patient-centered outcomes. The purpose of this study is to benchmark outcomes and experiences of patients undergoing colorectal surgery at a tertiary Veterans Affairs Medical Center for a 10-year period. Materials and Methods: Veterans who underwent nonemergent colorectal procedures between 2008 and 2018 were identified using targeted Current Procedural Terminology (CPT) codes and the Computerized Patient Record System. Patient outcomes were captured using the Veterans Affairs Surgical Quality Improvement Program and focused on length of stay and aggregate postoperative morbidity profiles. SAS® Version 9.4 (SAS Institute Inc., Cary, NC) was used for all data analysis with P < .05 used to indicate significance. Results: In total, 327 patients underwent colon/rectal resection at our medical center. Of whom 95% of patients were male and the average age was 66 years. The median length of stay after surgery was 8 days. Within the 30-day postoperative period, the composite morbidity score was 24.1%: most notable being superficial surgical site infections (6.5%), wound dehiscence (4.6%), and pneumonia (3.1%). Over the course of the study period, the laparoscopic approach increased in utilization, with 22.2% of cases performed laparoscopically in 2008 that rose to 61.1% in 2018. Conclusion: Cataloging this decade of practice provides a foundation for future changes in the field of colorectal surgery and in the treatment of veterans. Understanding historical outcomes should help identify areas for ongoing process improvement and guide targeted approaches to quality metrics.

Trends in Health Care-Associated Infection Prevention Practices in US Veterans Affairs Hospitals From 2005 to 2017.

Importance: Health care-associated infection (HAI) is associated with substantial harm. To reduce HAI, the largest integrated health care system in the United States-the Veterans Health Administration-was an early adopter of infection prevention policies and initiatives. Whether these efforts translated into increased use of practices to prevent HAI in Veterans Affairs (VA) hospitals is unknown. Objective: To evaluate changes over time in infection prevention practices and the perception of the importance of infection prevention to hospital leadership. Design, Settings, and Participants: For this survey study, every 4 years between 2005 and 2017, infection preventionists were surveyed at all VA hospitals on use of practices associated with common HAIs, including central line-associated bloodstream infection (CLABSI), catheter-associated urinary tract infection (CAUTI), ventilator-associated pneumonia (VAP), and (beginning in 2013) Clostridioides difficile infection. Data analysis was performed from February 1, 2019, to July 1, 2019. Main Outcomes and Measures: Reported regular use of key infection prevention practices and perceived importance of infection prevention to hospital leadership. Results: Between 2005 and 2017, 320 total surveys were completed with response rates ranging from 59% (73 of 124) in 2017 to 80% (95 of 119) in 2005. Use of 12 different infection prevention practices increased. Since 2013, 92% (69 of 75) to 100% of VA hospitals reported regular use of key infection prevention practices for C difficile infection and CLABSI. In contrast, adoption of many practices to prevent CAUTI, although increasing, have lagged. Despite reported increases in the use of some practices for VAP such as semirecumbent positioning (89% [79 of 89] in 2005 vs 97% [61 of 63] in 2017, P = .007 for trend) and subglottic secretion drainage (23% [19 of 84] in 2005 vs 65% [40 of 62] in 2017, P < .001), use of other key practices such as daily interruptions of sedation (85% [55 of 65] in 2009 vs 87% [54 of 62] in 2017, P = .66) and early mobilization (81% [52 of 64] in 2013 vs 82% [51 of 62] in 2017, P = .88) has not increased. Antibiotic stewardship programs are now reported in nearly every VA hospital (97% [71 of 73]); however, some hospitals report practices for microbiologic testing for HAIs (eg, 22% [16 of 72] report routine urine culture testing in 2017) that could also contribute to antibiotic overuse. Conclusions and Relevance: From 2005 to 2017, reported use of 12 different infection prevention practices increased in VA hospitals. Areas for continued improvement of infection prevention practices appear to include CAUTI, certain VAP practices, and diagnostic stewardship for HAI. The reported adoption of many infection prevention practices in VA hospitals was higher than in non-VA hospitals. As hospitals continue to merge and health systems become increasingly integrated, these successes could help inform patient safety broadly.

Trends in Hospitalization, Management, and Clinical Outcomes Among Veterans With Critical Limb Ischemia.

BACKGROUND: Contemporary patterns in management and outcomes of critical limb ischemia among United States veterans are unknown. METHODS: We used Veterans Health Administration data to identify patients admitted for critical limb ischemia between 2005 and 2014. We examined temporal trends in incidence, management, and outcomes. RESULTS: A total of 20 938 veterans with critical limb ischemia were hospitalized between 2005 and 2014. Mean age was 67.8 years. Incidence decreased from 0.3 to 0.24 per 1000 persons from 2005 to 2013, P<0.01. During the study period, there was a temporal increase in use of revascularization within 90 days of hospitalization-endovascular (11.2% in 2005 to 18.4% in 2014), surgical (23.8% in 2005 to 26.4% in 2014), and hybrid (6.2% in 2005 to 13.1% in 2014, P value for trend <0.01). Statin prescriptions increased from 47.4% in 2005 to 60.9% in 2014 (P value for trend <0.01). There was a significant decline in risk-adjusted mortality (11.8% in 2005 to 9.7% in 2014) and major amputation (19.8% in 2005 to 12.9% in 2014; P value for trend <0.01 for both) at 90 days. In adjusted analyses, revascularization was associated with a lower risk of mortality (RR, 0.45 [95% CI, 0.41-0.50]; P<0.001) and major amputation at 90 days (RR, 0.23 [95% CI, 0.21-0.26]; P<0.001). Nearly half of the patients who underwent amputation did not receive an invasive vascular procedure within the preceding 90 days. There was large site-level variation in the use of revascularization (median rate, 41.7% [interquartile range, 12.5%-53.2%]). Differences in patient case-mix explained only 8% of site-level variation in receipt of revascularization. CONCLUSIONS: Over the past decade, use of revascularization increased among veterans with critical limb ischemia, which was accompanied by a reduction in mortality and major amputation. However, opportunities to further improve care in this high-risk population still remain.

Lower Post Myocardial Infarction Mortality Among Women Treated at Veterans Affairs Hospitals Compared to Men.

BACKGROUND: There is conflicting evidence about whether mortality after myocardial infarction is higher among women than among men. This study aimed to compare sex differences in post myocardial infarction mortality in the Veterans Affairs system, a setting where the predominant subjects are men. MATERIALS AND METHODS: The Veterans Affairs Corporate Data Warehouse inpatient and laboratory chemistry databases were used to identify patients diagnosed with acute myocardial infarction from inpatient records from January 1st, 2005 to April 25th, 2015. Mortality data was obtained through the Veterans Affairs death registry. RESULTS: A total of 130,241 patients were identified; 127,711 men (98%) and 2,530 women (2%). Men typically had more comorbidities including congestive heart failure (54% vs. 46%, P value < 0.001), diabetes mellitus (54% vs. 48%, P value < 0.001), and chronic kidney disease (39% vs. 28%, P value < 0.001). The peak troponin-I was significantly higher among men (16.0 vs. 10.7 ng/mL, P value = 0.03). The mean follow-up time was 1490.67 ± 8 days. After adjusting for differences in demographics and comorbidities, women had a significantly lower risk of mortality (hazard ration [HR]: 0.747, P value < 0.0001) as compared to men. CONCLUSIONS: In a health care system where the predominant subjects are men, women had better short- and long-term survival than men after an acute myocardial infarction. Further investigation is warranted to determine the reasons behind the improved outcomes in women post myocardial infarction in the veteran population.

Ketamine Administration During Hospitalization Is Not Associated With Posttraumatic Stress Disorder Outcomes in Military Combat Casualties: A Matched Cohort Study.

BACKGROUND: Ketamine is routinely used within the context of combat casualty care. Despite early concerns that ketamine administration may be associated with elevated risk of posttraumatic stress disorder (PTSD), more recent evidence suggests no relationship. Because PTSD occurs with regular frequency in Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) Service Members (SMs) and combat-related injuries are associated with higher likelihood of PTSD, it is important to investigate the relationship between ketamine exposure during inpatient medical and surgical care and PTSD symptoms in OIF/OEF SMs. METHODS: Medical record data from OIF/OEF SMs medically evacuated from combat (N = 1158) included demographic characteristics, injury severity, body areas injured, and PTSD Checklist (PCL) scores. The primary analysis assessed the association between ketamine versus nonketamine exposure on positive PTSD screen (logistic regression) and PCL scores (linear regression) after using 1:1 propensity score matching to adjust for available potential confounding variables. Because there were 2 primary outcomes, the binary positive PTSD screen (yes/no) and continuous PCL score, the significance level was set at P ≤ .025. In sensitivity analyses, propensity scores were used to match ketamine to nonketamine records in a 1:4 ratio, as well as to conduct inverse probability treatment weighting (IPTW). Regressions examining the relationship between ketamine exposure and outcomes were repeated for unconditional, 1:4 matching, and IPTW models. RESULTS: In the sample, 107 received ketamine and 1051 did not. In the logistic regression, the probability of a positive PTSD screen was not significantly different between ketamine versus nonketamine patients (odds ratio [OR] = 1.28; 95% confidence interval [CI], 0.48-3.47; P = .62). In the linear regression, PCL scores were not significantly different between ketamine versus nonketamine patients (mean difference = 1.98 [95% CI, -0.99 to 4.96]; P = .19). The results were consistent in the unconditional, 1:4 matching, and IPTW models. CONCLUSIONS: No differences in PTSD screening risk or symptom levels between ketamine exposed and nonexposed were found. Given the small sample size, wide CIs of the effects, and additional confounds inherent to retrospective studies, future studies are needed to examine the complex relationships between ketamine and psychological symptoms.

Outcome of prolonged video-EEG monitoring in a new VA monitoring unit.

BACKGROUND AND OBJECTIVE: For patients with refractory seizures or seizure-like activity, prolonged inpatient video-electroencephalography (EEG) (v-EEG) is standard of care to guide diagnosis and management. The purpose of this study was to describe the outcome of v-EEG in a new Veterans' Administration (VA) hospital epilepsy monitoring unit (EMU). METHODS: We reviewed all prolonged (>24 h) inpatient v-EEGs performed in our EMU (2 beds) at the James A Haley VA in Tampa, FL over a five-and-a-half-year period (11/2013-07/2019). A total of 216 prolonged v-EEGs were performed. The patient population consisted of adult veterans (185 males, 31 females) ranging from 21 years to 89 years old (mean 52.5). The duration of monitoring ranged from 24 h to 9 days (mean 3.6 days). RESULTS: Of the 216 studies, 39 (18%) exclusively had epileptic seizures (ES). Of these, 37 (95%) had focal seizures, and 2 (5%) had generalized seizures. Of the 37 cases with focal seizures, all but 2 had clear ictal changes on EEG. Eighteen (8.5%) EEG studies revealed interictal epileptiform abnormalities without a clinical event. Sixty-eight (31.5%) of the v-EEGs had exclusively nonepileptic events (NEE). Of these, 27 (12.5%) were psychogenic nonepileptic seizures (PNES), and 41 (19%) were other NEE. Ninety-one (42%) of the studies were inconclusive, either because of lack of events captured (63) or because the events recorded were not the patient's typical episodes (27). SIGNIFICANCE: Compared to non-VA series, we found a lower proportion of PNES, and a higher proportion of inconclusive studies.

DNA methylation profiles are associated with complex regional pain syndrome after traumatic injury.

Factors contributing to development of complex regional pain syndrome (CRPS) are not fully understood. This study examined possible epigenetic mechanisms that may contribute to CRPS after traumatic injury. DNA methylation profiles were compared between individuals developing CRPS (n = 9) and those developing non-CRPS neuropathic pain (n = 38) after undergoing amputation following military trauma. Linear Models for Microarray (LIMMA) analyses revealed 48 differentially methylated cytosine-phosphate-guanine dinucleotide (CpG) sites between groups (unadjusted P's < 0.005), with the top gene COL11A1 meeting Bonferroni-adjusted P < 0.05. The second largest differential methylation was observed for the HLA-DRB6 gene, an immune-related gene linked previously to CRPS in a small gene expression study. For all but 7 of the significant CpG sites, the CRPS group was hypomethylated. Numerous functional Gene Ontology-Biological Process categories were significantly enriched (false discovery rate-adjusted q value <0.15), including multiple immune-related categories (eg, activation of immune response, immune system development, regulation of immune system processes, and antigen processing and presentation). Differentially methylated genes were more highly connected in human protein-protein networks than expected by chance (P < 0.05), supporting the biological relevance of the findings. Results were validated in an independent sample linking a DNA biobank with electronic health records (n = 126 CRPS phenotype, n = 19,768 non-CRPS chronic pain phenotype). Analyses using PrediXcan methodology indicated differences in the genetically determined component of gene expression in 7 of 48 genes identified in methylation analyses (P's < 0.02). Results suggest that immune- and inflammatory-related factors might confer risk of developing CRPS after traumatic injury. Validation findings demonstrate the potential of using electronic health records linked to DNA for genomic studies of CRPS.

Mitral Valve Repair Rate at a Veterans Affairs Hospital Utilizing a Multidisciplinary Heart Team.

Between 2000 and 2008, the mitral valve (MV) repair rate in patients with severe mitral regurgitation at our low-volume Veterans Affairs hospital was 21%. After instituting a multidisciplinary valve team in 2009, we determined whether this rate increased and characterized the outcomes of patients with degenerative disease. We retrospectively reviewed data from 103 MV operations performed at our hospital between 1/2009 and 8/2016. MV pathology was categorized as degenerative, rheumatic, endocarditis, ischemic, hypertrophic cardiomyopathy, or failed prior MV repair. The surgical techniques used for MV repair were reviewed. For the patients with degenerative disease who underwent MV repair, we assessed leaflet involvement and postoperative valve function. For the full cohort, the MV repair rate was 67% and the 30-day mortality rate was 0.97%. Of the 74 patients with degenerative disease, 64 (86.5%) underwent MV repair (none required reoperation). For these patients, the MV repair rate was significantly higher when the surgical approach was sternotomy rather than minimally invasive right minithoracotomy (92.5% vs 71.4%, P = 0.03). After MV repair, 95.3% of the degenerative disease patients had mild or less mitral regurgitation; median echocardiography follow-up time was 555 days. Anatomic features associated with a reduced MV repair rate in patients with degenerative disease were dystrophic leaflet calcification and severe mitral annular calcification. In an institution with a low volume of MV operations, preoperative surgical planning with a multidisciplinary valve team was associated with improved MV repair rates and excellent repair quality in patients with degenerative valve disease.

Risk Trajectories for Readmission and Death After Cirrhosis-Related Hospitalization.

INTRODUCTION: Patients hospitalized for cirrhosis are at high risk for readmission and death for the first 30 days following discharge. However, there is no information on how these risks dynamically change over a full year after discharge. Our aim was to determine the absolute risks of first readmission and death and characterize these changes in the first year following hospital discharge. METHODS: We conducted a retrospective cohort study of patients who were hospitalized with cirrhosis at all Veterans Affairs hospitals and discharged home between 01/01/2010 and 12/31/2013. We used separate survival models to determine risk of first readmission and death after hospital discharge. We also examined the absolute daily risks for first readmission and death by day and identified the time required for risks of readmission and death to decline 50% and 75% from maximum values. RESULTS: Of the 38,955 patients who survived index hospitalization for cirrhosis, 23,318 patients (59.9%) had at least one readmission and 11,567 patients (29.7%) died within the first year. Daily risk of readmission was the highest on day 1 (1.23%) and declined 50% by day 71 and 75% by day 260. After 1 year, daily risk of readmission did not plateau. Daily risk of death was the highest on day 1 (0.78%) and declined 50% by day 31 and 75% by day 64. CONCLUSION: The risk of readmission and death after cirrhosis-related hospitalization remains elevated for prolonged periods. Patients and providers should remain vigilant for clinical health deterioration beyond the first 30 days following hospitalization.

Long-term prescribing of nitrofurantoin for urinary tract infections (UTI) in veterans with spinal cord injury (SCI).

CONTEXT/OBJECTIVE: To evaluate the impact of long-term nitrofurantoin for UTI prophylaxis in veterans with SCI. DESIGN: Matched pairs study. SETTING: Veterans cared for at VA facilities from 10/1/2012-9/30/2013. PARTICIPANTS: Veterans. INTERVENTIONS: n/a. OUTCOMES MEASURES: UTI, positive urine cultures, resistant cultures. METHODS: Cases receiving long-term nitrofurantoin (≥90 days supply) were matched to controls by facility. Controls were patients who did not receive long-term nitrofurantoin with a history of ≥3 positive urine cultures and at least one diagnosis of UTI or asymptomatic bacteriuria in the previous year. RESULTS: 122 SCI cases were identified and matched to 196 controls. After adjusting for differences in baseline demographic characteristics, UTIs were less frequent in cases (OR = 0.60 [95% CI 0.44-0.72]). Cases had a greater mean number of days between positive urine cultures as compared to controls (<0.0001). Cases were more likely to have isolates resistant to nitrofurantoin (P ≤ 0.0001); however, the frequency of multi-drug resistant organisms isolated from the urine was not significantly different. CONCLUSIONS: Long-term prescription of nitrofurantoin may reduce UTIs in veterans with SCI and there is no evidence that it promotes multi-drug resistance. Future prospective studies should be conducted prior to incorporating routine use of long-term nitrofurantoin into clinical care.

Off-Pump Versus On-Pump: Long-Term Outcomes After Coronary Artery Bypass in a Veteran Population.

OBJECTIVES: The authors sought to investigate long-term outcomes after revascularization with and without use of cardiopulmonary bypass and hypothesized that off-pump would be comparable with on-pump. The primary outcome of interest was survival, and secondary outcomes were need for reintervention for revascularization or new diagnosis of myocardial infarction occurring any time after surgery during the 8- to 12-year follow-up period. DESIGN: Retrospective cohort analysis. SETTING: Veterans Affairs Medical Center. PARTICIPANTS: All patients undergoing primary isolated coronary bypass between January 1, 2004, and December 31, 2008 (n = 555). INTERVENTIONS: Coronary artery bypass on-pump (n = 238) or off-pump (n = 317). MEASUREMENTS AND MAIN RESULTS: Demographic and clinical variables were documented, including information on mortality, new myocardial infarction, and need for reintervention in the 8- to 12-year period after surgery. The on-pump and off-pump groups were similar regarding all demographic and clinical variables (p > 0.05), except for higher incidence of prior percutaneous coronary intervention in the off-pump group. There were more perioperative complications in the on-pump group (p = 0.007) and a greater number of grafts used (p = 0.000). Kaplan-Meier survival analysis demonstrated no significant difference (p > 0.05) in overall survival, reintervention-free survival, or postoperative myocardial infarction-free survival between patients who underwent bypass grafting on-pump or off-pump over extended follow-up averaging 10years. CONCLUSIONS: The present study's data did not show differences in key long-term outcomes between patients who underwent revascularization with or without cardiopulmonary bypass, supporting the idea that both methods achieve similar late results regarding overall survival, need for reintervention, and postoperative myocardial infarction.

Barriers and Facilitators to Implementation of Pharmacotherapy for Opioid Use Disorders in VHA Residential Treatment Programs.

OBJECTIVE: Despite evidence of effectiveness, pharmacotherapy-methadone, buprenorphine, or naltrexone-is prescribed to less than 35% of Veterans Health Administration (VHA) patients diagnosed with opioid use disorder (OUD). Among veterans whose OUD treatment is provided in VHA residential programs, factors influencing pharmacotherapy implementation are unknown. We examined barriers to and facilitators of pharmacotherapy for OUD among patients diagnosed with OUD in VHA residential programs to inform the development of implementation strategies to improve medication receipt. METHOD: VHA electronic health records and program survey data were used to describe pharmacotherapy provided to a national cohort of VHA patients with OUD in residential treatment programs (N = 4,323, 6% female). Staff members (N = 63, 57% women) from 44 residential programs (response rate = 32%) participated in interviews. Barriers to and facilitators of pharmacotherapy for OUD were identified from transcripts using thematic analysis. RESULTS: Across all 97 residential treatment programs, the average rate of pharmacotherapy for OUD was 21% (range: 0%-67%). Reported barriers included provider or program philosophy against pharmacotherapy, a lack of care coordination with nonresidential treatment settings, and provider perceptions of low patient interest or need. Facilitators included having a prescriber on staff, education and training for patients and staff, and support from leadership. CONCLUSIONS: Contrary to our hypothesis, barriers to and facilitators of pharmacotherapy for OUD in VHA residential treatment programs were consistent with prior research in outpatient settings. Intensive educational programs, such as academic detailing, and policy changes such as mandating buprenorphine waiver training for VHA providers, may help improve receipt of pharmacotherapy for OUD.

Risk factors of opioid-induced adverse reactions in elderly male outpatients of Korea Veterans Hospital.

BACKGROUND: Risk factors associated with opioid-induced adverse reactions (OIARs) in the elderly population have not been well defined. The objective of this study was to determine effects of various risk factors on incidence of OIARs in male elderly patients. METHODS: A retrospective cohort study in Korea Veterans Hospital was performed. Data were analyzed in male patients aged 65 years and older who received morphine, oxycodone, or codeine. Binomial variables describing patient-related and drug-related characteristics were constructed. Associations between these variables and frequency of OIARs were determined. Odds ratio (OR) and adjusted odds ratio (AOR) were calculated from univariate and multivariable analyses, respectively. Attributable risk was obtained by (1-1/OR)*100%. RESULTS: Of 316 patients, 28% experienced at least one adverse event. The most common adverse events were gastrointestinal problems (n = 59) and central nerve system adverse effects (n = 20). The odds of OIARs in patients with opioid use ≥12 weeks was increased by 80% compared to those with opioid use < 12 weeks. Attributable risk of GABA analogues was 64~78% in constructed Models. Compared to codeine users, patients using morphine and oxycodone had 653 and 473% increased odds for OIARs, respectively. MME ≥ 60 mg/day had a 317% increased odds for OIARs (95% CI: 1.92-9.04) compared to MME < 60 mg/day. Opioid combination therapy had a 139% increased odds for OIARs compared to monotherapy. CONCLUSIONS: These findings have significant implications for clinical use of opioid in elderly patients. Our study suggests that low dose short-term use will pose less risk of OIARs for the elderly, whereas concomitant use of GABA analogues, strong opioids and dual-opioid therapy may increase the risk of OIARs. Therefore, clinician should carefully monitor patients when starting opioid therapy in older population.

Identifying Latent Subgroups of High-Risk Patients Using Risk Score Trajectories.

OBJECTIVE: Many healthcare systems employ population-based risk scores to prospectively identify patients at high risk of poor outcomes, but it is unclear whether single point-in-time scores adequately represent future risk. We sought to identify and characterize latent subgroups of high-risk patients based on risk score trajectories. STUDY DESIGN: Observational study of 7289 patients discharged from Veterans Health Administration (VA) hospitals during a 1-week period in November 2012 and categorized in the top 5th percentile of risk for hospitalization. METHODS: Using VA administrative data, we calculated weekly risk scores using the validated Care Assessment Needs model, reflecting the predicted probability of hospitalization. We applied the non-parametric k-means algorithm to identify latent subgroups of patients based on the trajectory of patients' hospitalization probability over a 2-year period. We then compared baseline sociodemographic characteristics, comorbidities, health service use, and social instability markers between identified latent subgroups. RESULTS: The best-fitting model identified two subgroups: moderately high and persistently high risk. The moderately high subgroup included 65% of patients and was characterized by moderate subgroup-level hospitalization probability decreasing from 0.22 to 0.10 between weeks 1 and 66, then remaining constant through the study end. The persistently high subgroup, comprising the remaining 35% of patients, had a subgroup-level probability increasing from 0.38 to 0.41 between weeks 1 and 52, and declining to 0.30 at study end. Persistently high-risk patients were older, had higher prevalence of social instability and comorbidities, and used more health services. CONCLUSIONS: On average, one third of patients initially identified as high risk stayed at very high risk over a 2-year follow-up period, while risk for the other two thirds decreased to a moderately high level. This suggests that multiple approaches may be needed to address high-risk patient needs longitudinally or intermittently.