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1.  Progression of autosomal dominant kidney disease: measurement of the stage transitions of chronic kidney disease 
Drugs in Context  2015;4:212275.
Autosomal dominant polycystic kidney disease (ADPKD) is a progressive genetic disorder characterized by the development of numerous kidney cysts that result in kidney failure. Little is known regarding the key patient characteristics and utilization of healthcare resources for ADPKD patients along the continuum of disease progression. This observational study was designed to describe the characteristics of ADPKD patients and compare them with those of patients with other chronic kidney diseases.
This retrospective cohort study involved patients with a claim for ADPKD or PKD unspecified from 1/1/2000–2/28/2013 and ≥6 months of previous continuous enrollment (baseline) within a large database of administrative claims in the USA. A random sample of chronic kidney disease (CKD) patients served as comparators. For a subset of ADPKD patients who had only a diagnosis code of unspecified PKD, abstraction of medical records was undertaken to estimate the proportion of patients who had medical chart-confirmed ADPKD. In patients with linked electronic laboratory data, the estimated glomerular filtration rate was calculated via serum creatinine values to determine CKD stage at baseline and during follow-up. Proportions of patients transitioning to another stage and the mean age at transition were calculated.
ADPKD patients were, in general, younger and had fewer physician visits, but had more specific comorbidities at observation start compared with CKD patients. ADPKD patients had a longer time in the milder stages and longer duration before recorded transition to a more severe stage compared with CKD patients. Patients with ADPKD at risk of rapid progression had a shorter time-to-end-stage renal disease than patients with CKD and ADPKD patients not at risk, but stage duration was similar between ADPKD patients at risk and those not at risk.
These results suggest that distribution of patients by age at transition to next stage may be useful for identification of ADPKD patients at risk of rapid progression. The results also suggest that medical claims with diagnosis codes for “unspecified PKD”, in absence of a diagnosis code for autosomal recessive polycystic kidney disease, may be a good proxy for ADPKD.
PMCID: PMC4407687  PMID: 25922609
autosomal dominant polycystic kidney disease; ADPKD; chronic kidney disease; serum creatinine; disease stage; end-stage renal disease
2.  Adherence to risk evaluation and mitigation strategies (REMS) requirements for monthly testing of liver function 
Drugs in Context  2015;4:212272.
Risk evaluation and mitigation strategies (REMS), as mandated by the US Food and Drug Administration (FDA) for medications with the potential for harm, are increasingly incorporating rigid protocols for patient evaluation, but little is known about compliance with these programs. Despite the inherent limitations, data on administrative claims may provide an opportunity to investigate adherence to these programs.
We assessed adherence to liver function test (LFT) requirements included in the REMS program for bosentan through use of administrative claims. Patients observed in the Optum Research Database who were initiators of bosentan from November 20, 2001 to March 31, 2013 were included. Adherence to LFTs was calculated using pharmacy claims for bosentan dispensation and medical claims for laboratory services, and was assessed at the time of drug initiation and within specified time intervals throughout follow-up.
Of 742 patients, 523 (70.5%) had ≥1 qualifying LFT. Among patients with ≥12 dispensations, claims for LFTs at individual dispensations were 53.2–64.0%. Median proportion of dispensations with ≥1 LFT was 0.8 among patients with ≥6 (interquartile range, 0.7–1.0) or ≥12 (0.7–0.9) dispensations. Adherence was 90–100% for 33.3% of all initiators, whereas 29.3% of initiators were non-adherent (defined as <50% of on-therapy LFTs).
Analyses of administrative claims suggest that the REMS program for bosentan may not have adequately guaranteed adherence to the program’s monthly monitoring of LFTs. Such investigations of existing REMS programs may provide insight on how to accomplish more successful evaluation of REMS.
PMCID: PMC4335780  PMID: 25709706
risk evaluation; REMS; liver function test; adherence; compliance; FDA; patient assessment; administrative claims
3.  Depression Following Thrombotic Cardiovascular Events in Elderly Medicare Beneficiaries: Risk of Morbidity and Mortality 
Purpose. Depression and antidepressant use may independently increase the risk of acute myocardial infarction and mortality in adults. However, no studies have looked at the effect of depression on a broader thrombotic event outcome, assessed antidepressant use, or evaluated elderly adults. Methods. A cohort of 7,051 community-dwelling elderly beneficiaries who experienced a thrombotic cardiovascular event (TCE) were pooled from the 1997 to 2002 Medicare Current Beneficiary Survey and followed for 12 months. Baseline characteristics, antidepressant utilization, and death were ascertained from the survey, while indexed TCE, recurrent TCE, and depression (within 6 months of indexed TCE) were taken from ICD-9 codes on Medicare claims. Time to death and first recurrent TCE were assessed using descriptive and multivariate statistics. Results. Of the elders with a depression claim, 71.6% had a recurrent TCE and 4.7% died within 12 months of their indexed TCE, compared to 67.6% and 3.9% of those elders without a depression claim. Of the antidepressant users, 72.6% experienced a recurrent TCE and 3.9% died, compared to 73.7% and 4.6% in the subset of selective serotonin reuptake inhibitor (SSRI) users. Depression was associated with a shorter time to death (P = .008) in the unadjusted analysis. However, all adjusted comparisons revealed no effect by depression, antidepressant use, or SSRI use. Conclusions. Depression was not associated with time to death or recurrent TCEs in this study. Antidepressant use, including measures of any antidepressant use and SSRI use, was not associated with shorter time to death or recurrent TCE.
PMCID: PMC2800999  PMID: 20069046
4.  Cachexia & debility diagnoses in hospitalized children and adolescents with complex chronic conditions: evidence from the Kids’ Inpatient Database 
Drugs in Context  2015;4:212277.
To characterize the frequency, cost, and hospital-reported outcomes of cachexia and debility in children and adolescents with complex chronic conditions (CCCs).
We identified children and adolescents (aged ≤20 years) with CCCs, cachexia, and debility in the Kids’ Inpatient Database [Healthcare Cost and Utilization Project, Agency for Healthcare Research & Quality]. We then compared the characteristics of patients and hospitalizations, including cost and duration of stay, for CCCs with and without cachexia and/or debility. We examined factors that predict risk of inpatient mortality in children and adolescents with CCCs using a logistic regression model. We examined factors that impact duration of stay and cost in children and adolescents with CCCs using negative binomial regression models. All costs are reported in US dollars in 2014 using Consumer Price Index inflation adjustment.
We estimated the incidence of hospitalization of cachexia in children and adolescents with CCCs at 1,395 discharges during the sample period, which ranged from 277 discharges in 2003 to 473 discharges in 2012. We estimated the incidence of hospitalization due to debility in children and adolescents with CCCs at 421 discharges during the sample period, which ranged from 39 discharges in 2003 to 217 discharges in 2012. Cachexia was associated with a 60% increase in the risk of inpatient mortality, whereas debility was associated with a 40% decrease in the risk of mortality. Cachexia and debility increased duration of stay in hospital (17% and 39% longer stays, respectively). Median cost of hospitalization was $15,441.59 and $23,796.16 for children and adolescents with cachexia and debility, respectively.
Incidence of hospitalization for cachexia in children and adolescents with CCCs is less than that for adults but the frequency of cachexia diagnoses increased over time. Estimates of the incidence of hospitalization with debility in children and adolescents with CCCs have not been reported, but our study demonstrates that the frequency of these discharges is also increasing.
PMCID: PMC4353190  PMID: 25767549
adolescent; cachexia; child; complex chronic conditions; cost analysis; debility; HIV; pediatrics
5.  Economic burden of chronic bronchitis in the United States: a retrospective case-control study 
Chronic bronchitis (CB) is often misdiagnosed or diagnosed at a later stage of chronic obstructive pulmonary disease (COPD). We examined how this later diagnosis may impact health care costs and utilization during the 12 months prior to and 24 months post initial CB diagnosis.
This retrospective case-control analysis used claims data from a large US database from July 1, 2003 through June 30, 2007. Patients with CB aged 40 years and older were propensity matched (N = 11,674) to patients without evidence of COPD or asthma by demographics, CB diagnosis quarter/year, and comorbidities. Group differences were assessed using Student’s t-test and Pearson chi-square test statistics.
Six months prediagnosis, CB patients had higher frequencies of any hospitalization (9.6%, 6.7%; P < 0.05), emergency department/urgent care visits (13.3%, 6.7%; P < 0.05), and prescriptions (97.3%, 94.1%; P < 0.05). Six months postdiagnosis, CB patients had 5.6 times more hospitalizations (P < 0.05) and 3.1 times more emergency department/urgent care visits (P < 0.05) compared with controls. Mean total costs (US$) for CB patients 12 months prediagnosis were significantly higher than controls (months 12–7: $4212, $3826; P < 0.05; months 6–1: $5289, $4285; P < 0.05). CB patients had higher mean total costs ($8919; P < 0.05) 6 months postdiagnosis. Costs remained $2429 higher for CB patients 19–24 months postdiagnosis (P < 0.05).
Health care costs and utilization among CB patients are increased both prior to diagnosis and during the 2 years postdiagnosis. This study suggests that not accurately diagnosing CB early has a substantial impact on health care costs, and that the economic burden for CB patients remains elevated even after adjustment for comorbidities associated with COPD.
PMCID: PMC3034282  PMID: 21311695
chronic bronchitis; burden; economic; chronic obstructive pulmonary disease
6.  Cost-effectiveness of combination fluticasone propionate–salmeterol 250/50 μg versus salmeterol in severe COPD patients 
To estimate the cost-effectiveness of fluticasone propionate–salmeterol combination (FSC) compared to salmeterol for maintenance therapy in severe chronic obstructive pulmonary disease (COPD).
Study design:
Pooled economic analysis.
We performed an economic analysis of pooled data from two randomized clinical trials (combined N = 1554) that evaluated the effect of maintenance therapy with FSC (250/50 μg twice daily) or salmeterol (50 μg twice daily) on exacerbation rates in patients with severe COPD. We calculated exacerbation rates and applied standardized costs to exacerbation-related health care utilization reported in the trials (office, urgent care, and emergency department visits; hospitalizations; and oral corticosteroids and antibiotics) to determine cost differences between FSC and salmeterol treatment outcomes.
Annual rates of any exacerbation and moderate/severe exacerbation were lower in the FSC group than the salmeterol group (4.91 vs 5.78 and 1.32 vs 2.00 respectively, both P < 0.05). Total adjusted annual COPD related exacerbation and therapeutic costs were $4,842 (95% CI; $4,731–$4,952) in the FSC group and $5,066 (95% CI; $4,937–$5,195) in the salmeterol group.
FSC combination therapy is associated with reduced risk of any exacerbation and moderate/severe exacerbation, and incurs lower annual COPD-related health care costs compared to treatment with salmeterol. This analysis demonstrates that FSC therapy may be advantageous from both a clinical and cost-benefit standpoint for patients with severe COPD.
PMCID: PMC2921685  PMID: 20714371
COPD; cost-effectiveness analysis; economic; maintenance therapy
7.  A cross-sectional retrospective analysis of the regionalization of complex surgery 
BMC Surgery  2014;14:55.
The Veterans Health Administration (VHA) system has assigned a surgical complexity level to each of its medical centers by specifying requirements to perform standard, intermediate or complex surgical procedures. No study to similarly describe the patterns of relative surgical complexity among a population of United States (U.S) civilian hospitals has been completed.
Design: single year, retrospective, cross-sectional.
Setting/Participants: the study used Florida Inpatient Discharge Data from short-term acute hospitals for calendar year 2009. Two hundred hospitals with 2,542,920 discharges were organized into four quartiles (Q 1, 2, 3, 4) based on the number of complex procedures per hospital. The VHA surgical complexity matrix was applied to assign relative complexity to each procedure. The Clinical Classification Software (CCS) system assigned complex procedures to clinically meaningful groups. For outcome comparisons, propensity score matching methods adjusted for the surgical procedure, age, gender, race, comorbidities, mechanical ventilator use and type of admission.
Main Outcome Measures: in-hospital mortality and length-of-stay (LOS).
Only 5.2% of all inpatient discharges involve a complex procedure. The highest volume complex procedure hospitals (Q4) have 49.8% of all discharges but 70.1% of all complex procedures. In the 133,436 discharges with a primary complex procedure, 374 separate specific procedures are identified, only about one third of which are performed in the lowest volume complex procedure (Q1) hospitals. Complex operations of the digestive, respiratory, integumentary and musculoskeletal systems are the least concentrated and proportionately more likely to occur in the lower volume hospitals. Operations of the cardiovascular system and certain technology dependent miscellaneous diagnostic and therapeutic procedures are the most concentrated in high volume hospitals. Organ transplants are only done in Q4 hospitals. There were no significant differences in in-hospital mortality rates and the longest lengths of stay were found in higher volume hospitals.
Complex surgery in Florida is effectively regionalized so that small volume hospitals operating within the range of complex procedures appropriate to their capabilities provide no increased risk of post surgical mortality.
PMCID: PMC4147936  PMID: 25128011
Surgical complexity; Surgical outcomes; Regionalization of surgical services
8.  One-year prevalence, comorbidities and cost of cachexia-related inpatient admissions in the USA 
Drugs in Context  2014;3:212265.
Cachexia is a condition characterized as a loss in body mass or metabolic dysfunction and is associated with several prevalent chronic health conditions including many cancers, COPD, HIV, and kidney disease, with between 10 and 50% of patients with these conditions having cachexia. Currently there is little research into cachexia and our objective is to characterize cachexia patients, their healthcare utilization, and associated hospitalization costs. Given the increasing prevalence of chronic diseases, it is important to better understand cachexia so that the condition can be better diagnosed and managed.
We utilized one year (2009) of the Nationwide Inpatient Sample (NIS). The NIS represents all inpatient stays at a random 20% sample of all hospitals within the United States. We grouped cachexia individuals by primary or secondary discharge diagnosis and then compared those with cachexia to all others in terms of length of stay (LOS) and total cost. Finally we looked into factors predicting increased LOS using a negative binomial model.
We estimated US prevalence for cachexia-related inpatient admissions at 161,898 cases. Cachexia patients were older, with an average age of 67.95 versus 48.10 years in their non-cachexia peers. Hospitalizations associated with cachexia had an increased LOS compared to non-cachexia patients (6 versus 3 days), with average costs per stay $4641.30 greater. Differences were seen in loss of function (LOF) with cachexia patients, mostly in the major LOF category (52.60%), whereas non-cachexia patients were spread between minor, moderate, and major LOF (36.28%, 36.11%, and 21.26%, respectively). Significant positive predictors of increased LOS among cachexia patients included urban hospital (IRR=1.21, non-teaching urban; IRR=1.23, teaching urban), having either major (IRR=1.41) or extreme (IRR=2.64) LOF, and having a primary diagnosis of pneumonia (IRR=1.15).
We have characterized cachexia and seen it associated with increased length of stay, increased cost, and more severe loss of function in patients compared to those without cachexia.
PMCID: PMC4130358  PMID: 25126097
muscle loss; cachexia; occurrence; outcomes research; patient costs; cancer cachexia; cardiac cachexia; chronic obstructive pulmonary disease
9.  Rising Costs of COPD and the Potential for Maintenance Therapy to Slow the Trend 
Chronic obstructive pulmonary disease (COPD) affects an estimated 14% of adults in the United States between the ages of 40 and 79 years. This progressive disease is characterized by persistent airflow limitation. The management of patients with COPD is focused on reducing risk factors, relieving symptoms, and preventing exacerbations.
To examine the peer-reviewed literature on the impact of maintenance therapy on the direct treatment costs of patients with COPD in the United States.
PubMed was searched for articles written in English that were published between 2000 and 2013, using the search terms “COPD,” “economics,” “exacerbation,” “maintenance,” and related terms. Articles reporting the results of longitudinal studies of the costs associated with the management of patients with COPD, the costs associated with hospitalizations for acute exacerbations of COPD, and randomized clinical trials evaluating the effects of maintenance therapy on the incidence of COPD exacerbations were included in this review.
The search identified a total of 277 articles, and 11 of these articles were deemed appropriate for inclusion in this review. The direct healthcare costs for patients with COPD increased by 38% between 1987 and 2007, and continued to increase by approximately 5% annually between 2006 and 2009. The costs associated with hospital admissions for patients with COPD accounted for the largest absolute increase ($2289 per admission in constant 2007 US dollars). Recent estimates suggest that the aggregate costs associated with the treatment of acute exacerbations are between $3.2 billion and $3.8 billion, and that annual healthcare costs are 10-fold greater for patients with COPD associated with acute exacerbations than for patients with COPD but without exacerbations. The results of 2 large clinical trials of maintenance therapy, including a long-acting cholinergic antagonist or a long-acting beta-2 agonist, showed a 16% to 17% reduction in the incidence of exacerbations compared with placebo. Nevertheless, maintenance therapy remains underutilized, with only 30% to 35% of patients with COPD in private and public health insurance plans receiving prescriptions for maintenance therapy.
The treatment of acute exacerbations of COPD remains the major driver of increasing healthcare costs associated with this condition. The appropriate use of maintenance therapy has been shown to reduce the incidence of exacerbations and has the potential to reduce overall costs associated with the management of patients with COPD.
PMCID: PMC4049119  PMID: 24991394
10.  Probabilistic data linkage: a case study of comparative effectiveness in COPD 
Drugs in Context  2013;2013:212258.
In this era of comparative effectiveness research, new, advanced techniques are being investigated by the research community to overcome the limitations of existing data sources. We describe the approach of probabilistic data linkage as a means to address this critical issue.
We employed a historical retrospective cohort design. Patients aged 40 and older with a principal or secondary diagnosis of COPD (ICD-9-CM codes 491.xx, 492.xx, and 496) and at least 3 years of continuous enrollment between January 1, 2004 and April 30, 2009 were selected from two US-based commercial administrative claims databases. The index date was designated as the date of the first claim (defined by a 12-month wash-out pre-index period) for the study drugs, for illustration purposes referred to as Treatment 1 or Treatment 2. The primary effectiveness measure was risk of any COPD-related exacerbation observed in the 12-month post-index period, with baseline characteristics being identified in the 12-month pre-index period.
The percentage of the study sample receiving Treatment 1 at index who had an exacerbation was 39.3% for Database A and 39.7% for Database B; for Treatment 2, the percentages were 46.3% and 47.1%, respectively. The event rate of hospitalizations in each database sample was nearly identical as were the odds ratio and corresponding confidence intervals from the adjusted logistic regression models (OR – Database A: 0.72, Database B: 0.74, Database A with imputed outcomes: 0.72).
The probabilistic linkage demonstrated that patients from different databases matched on similar pre-index characteristics may demonstrate similar outcomes in the post-index period.
PMCID: PMC3884745  PMID: 24432045
data linkage; medical record linkage; comparative effectiveness research; treatment effectiveness; COPD; outcomes research; ambulatory care; prescription drugs
11.  Severity of COPD at initial spirometry-confirmed diagnosis: data from medical charts and administrative claims 
This study was conducted to determine COPD severity at the time of diagnosis as confirmed by spirometry in patients treated in a US managed care setting.
Patients and methods
All patients with one or more inpatient stays, one or more emergency department visits, or two or more outpatient visits with diagnosis codes for COPD during 1994–2006 were identified from the Lovelace Patient Database. From this group, a subset of continuously enrolled patients with evidence in claims of a first available pulmonary function test or pulmonary clinic visit and a confirmatory claim for a COPD diagnosis was selected. Medical chart abstraction was undertaken for this subset to gather information for diagnosis and severity staging of each patient based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD.
Of the 12,491 patients with a primary or secondary COPD diagnosis between 1994 and 2006, there were 1520 continuously enrolled patients who comprised the study cohort. Among the 648 eligible records from patients with evidence of a pulmonary function test, 366 were identified by spirometry as having COPD of GOLD stage I or higher (average percentage of predicted forced expiratory volume in 1 second: 60%): 19% were diagnosed at the stage of mild disease (GOLD stage I); 50% at moderate disease (GOLD stage II); and 31% at severe or very severe disease (GOLD stage III or IV, respectively). The majority of patients in these groups were not receiving maintenance treatment.
The results demonstrate a very low incidence of early-stage diagnosis, confirmed by a pulmonary function test, of COPD in a large US sample and support calls for increased screening for COPD and treatment upon diagnosis.
PMCID: PMC3224652  PMID: 22135490
lung function; Global Initiative for Chronic Obstructive Lung Disease (GOLD); detection; early treatment
12.  The Positive Predictive Value of a Hyperkalemia Diagnosis in Automated Health Care Data 
Pharmacoepidemiology and drug safety  2010;19(11):1204-1208.
Our objectives were to determine performance of coded hyperkalemia diagnosis at identifying 1) clinically-evident hyperkalemia and 2) serum potassium ≥ 6 mmol/liter.
This retrospective observational study included 8,722 patients with diabetes within an integrated healthcare system who newly-initiated an angiotensin converting enzyme inhibitor, angiotensin receptor blocker, or spironolactone. The primary outcome was first hyperkalemia-associated event (hospitalization, emergency department visit or death within 24 hours of coded diagnosis and/or potassium ≥ 6 mmol/liter) during the first year of therapy. Medical records were reviewed.
Among a random sample of 99 patients not coded as having hyperkalemia, none had hyperkalemia upon record review. Among all 64 patients identified as having hyperkalemia, all had hospitalization or emergency department visit associated with coded diagnosis or elevated potassium. Of 55 with coded diagnosis, 42 (PPV 76%) had clinically-evident hyperkalemia; 32 (PPV 58%) had potassium ≥ 6. Of 9 identified using only potassium ≥ 6, 7 (PPV 78%) had clinically-evident hyperkalemia.
Nearly one-fourth of patients with coded diagnosis do not have clinically-evident hyperkalemia and nearly one-half do not have potassium ≥ 6. Because both false positives and negatives occur with coded diagnoses, medical record validation of hyperkalemia-associated outcomes is necessary.
PMCID: PMC2996391  PMID: 20878650
Hyperkalemia; positive predictive value; sensitivity; specificity; ACEi; ARB
13.  Wood Smoke Exposure and Gene Promoter Methylation Are Associated with Increased Risk for COPD in Smokers 
Rationale: Wood smoke–associated chronic obstructive pulmonary disease (COPD) is common in women in developing countries but has not been adequately described in developed countries.
Objectives: Our objective was to determine whether wood smoke exposure was a risk factor for COPD in a population of smokers in the United States and whether aberrant gene promoter methylation in sputum may modify this association.
Methods: For this cross-sectional study, 1,827 subjects were drawn from the Lovelace Smokers' Cohort, a predominantly female cohort of smokers. Wood smoke exposure was self-reported. Postbronchodilator spirometry was obtained, and COPD outcomes studied included percent predicted FEV1, airflow obstruction, and chronic bronchitis. Effect modification of wood smoke exposure with current cigarette smoke, ethnicity, sex, and promoter methylation of lung cancer-related genes in sputum on COPD outcomes were separately explored. Multivariable logistic and poisson regression models were used for binary and rate-based outcomes, respectively.
Measurements and Main Results: Self-reported wood smoke exposure was independently associated with a lower percent predicted FEV1 (point estimate [± SE] −0.03 ± 0.01) and a higher prevalence of airflow obstruction and chronic bronchitis (odds ratio, 1.96; 95% confidence interval, 1.52–2.52 and 1.64 (95% confidence interval, 1.31–2.06, respectively). These associations were stronger among current cigarette smokers, non-Hispanic whites, and men. Wood smoke exposure interacted in a multiplicative manner with aberrant promoter methylation of the p16 or GATA4 genes on lower percent predicted FEV1.
Conclusions: These studies identify a novel link between wood smoke exposure and gene promoter methylation that synergistically increases the risk for reduced lung function in cigarette smokers.
PMCID: PMC3001253  PMID: 20595226
wood smoke; cigarette smokers; airflow obstruction; gene promoter methylation in sputum DNA
14.  Diabetes and Drug-Associated Hyperkalemia: Effect of Potassium Monitoring 
Renin-angiotensin-aldosterone system (RAAS) inhibitors are associated with hyperkalemia, but there is little evidence demonstrating patients who receive potassium monitoring have a lower rate of hyperkalemia.
To evaluate the association between potassium monitoring and serious hyperkalemia-associated adverse outcomes among patients with diabetes newly initiating RAAS inhibitor therapy.
Retrospective observational study.
Patients with diabetes without end-stage renal disease initiating RAAS inhibitor therapy between 2001 and 2006 at three integrated health care systems.
Potassium monitoring and first hyperkalemia-associated adverse event during the initial year of therapy. Hyperkalemia-associated adverse events included hospitalizations, emergency department visits or deaths within 24 h of hyperkalemia diagnosis and/or diagnostic potassium ≥6 mmol/l. Incidence rates were calculated in person-years (p-y). We used inverse probability propensity score weighting to adjust for differences between patients with and without monitoring; Poisson regression was used to obtain adjusted relative risks.
A total of 19,391 of 27,355 patients (71%) received potassium monitoring. Serious hyperkalemia-associated events occurred at an incidence rate of 10.2 per 1,000 p-y. Compared to patients without monitoring, adjusted relative risk of hyperkalemia-associated adverse events among all patients with monitoring was 0.50 (0.37, 0.66); in the subset of patients who also had chronic kidney disease (n = 2,176), adjusted relative risk was 0.29 (0.18, 0.46).
Patients prescribed RAAS inhibitors who have both diabetes and chronic kidney disease and receive potassium monitoring are less likely to experience a serious hyperkalemia-associated adverse event compared to similar patients who did not receive potassium monitoring. This evidence supports existing consensus-based guidelines.
PMCID: PMC2842549  PMID: 20087674
hyperkalemia; hyperpotassemia; angiotensin-converting enzyme inhibitor; ACEi; angiotensin receptor blocker; ARB; spironolactone; RAAS inhibitor
15.  Comparative cost-effectiveness of a fluticasone-propionate/salmeterol combination versus anticholinergics as initial maintenance therapy for chronic obstructive pulmonary disease 
Relative costs and utilization-related outcomes of a fluticasone propionate 250 μg + salmeterol 50 μg combination (FSC), tiotropium bromide, and ipratropium as initial maintenance therapy in COPD have not been compared in a commercially-insured population.
This retrospective, observational cohort study used health care claims data from January 2004 to June 2009 from a large administrative database for patients aged ≥40 years with COPD. Time-to-first COPD-related health care event beginning 30 days following therapy initiation with FSC (n = 16,684), ipratropium alone or in fixed dose combination with albuterol (n = 14,449), or tiotropium (n = 12,659) was estimated using Cox proportional hazard models that controlled for differences in patient demographic characteristics, health care utilization, and comorbidities at baseline. Mean adjusted costs and numbers of COPD-related health care encounters and prescription medication fills were compared among patients with 12 months of follow-up (FSC, n = 12,595; ipratropium, n = 10,617; tiotropium, n = 9126).
With FSC as the reference, risk for a COPD-related hospitalization and/or emergency department visit was significantly higher for ipratropium (hazard ratio [HR] 1.64, 95% confidence interval [CI] 1.50–1.79) and tiotropium (HR 1.29, CI 1.17–1.41). Mean adjusted 12-month COPD-related total health care costs were lower for FSC ($2068, standard deviation [SD] $1190) than for ipratropium ($2841, SD $1858) and tiotropium ($2408, SD $1511, both P <0.05). Mean number of COPD-related hospitalizations, emergency department visits, and outpatient visits associated with an oral corticosteroid or antibiotic were also lower for FSC than for ipratropium and tiotropium (all P <0.05).
In this retrospective “real-world” observational sample of COPD patients, initiating treatment with FSC was associated with significantly better clinical and economic outcomes compared with short- and long-acting anticholinergic therapy. Consistent with the goal of preventing and reducing exacerbations advocated by global guidelines, the findings suggest that initiation of maintenance treatment with FSC may afford clinical benefits at a lower cost than anticholinergic treatment.
PMCID: PMC3034283  PMID: 21311689
chronic obstructive pulmonary disease; Advair®; tiotropium; ipratropium; utilization; costs
16.  Drug Use Patterns in Severely Mentally Ill Medicare Beneficiaries: Impact of Discontinuities in Drug Coverage 
Health Services Research  2008;43(2):496-514.
To describe the extent of drug coverage among severely mentally ill Medicare beneficiaries and to determine whether and to what extent discontinuities in prescription drug coverage influence the use of medications used to treat serious mental health conditions.
Data Source
1997–2001 Medicare Current Beneficiary Surveys.
Study Design
We use a zero-inflated negative binomial model to estimate: (1) the probability of not receiving any mental health drug and (2) the number of medications received, adjusting for age, race, income, census region, health status, and comorbidity. Severe mental illness is defined using inpatient and outpatient claims with ICD-9 codes of schizophrenia, other psychotic disorders, bipolar disorders, and major depression. Mental health medications include antidepressants, antipsychotics, mood stabilizers, anxiolytic/sedative-hypnotics, and stimulants. Prescription drug coverage is assessed as full coverage (0 percent discontinuities), no coverage (100 percent discontinuities), or as discontinuous coverage, measured as 1–25, 26–50, and 51–99 percent of time without coverage.
Data Collection/Extraction Methods
We constructed three 3-year longitudinal cohorts of severely mentally ill Medicare beneficiaries residing in the community (n = 901).
Principal Findings
Severely mentally ill Medicare beneficiaries with drug coverage discontinuities are more likely than their continuously insured peers not to receive medications used to treat mental health disorders, with the most significant impact seen in the probability of receiving any psychiatric medications. Analysis of two therapeutic classes—antidepressants and antipsychotics—revealed varying impacts of drug gaps on both probability of any drug use, as well as number of medications received among users.
Severely mentally ill Medicare beneficiaries may be particularly vulnerable to the Medicare Part D drug benefit design and, as such, warrant close evaluation and monitoring to insure adequate access to and utilization of medications used to manage mental illness.
PMCID: PMC2442367  PMID: 18370965
Drug coverage; mental health; prescription drugs; Medicare; access
17.  Cost and utilization of blood transfusion associated with spinal surgeries in the United States 
European Spine Journal  2006;16(3):353-363.
The purpose of this study was to examine factors associated with the utilization and cost of blood transfusion during and post-spinal fusion surgery. A retrospective, observational study of 42,029 inpatients undergoing spinal fusion surgery in United States hospitals participating in the PerspectiveTM Comparative Database for inpatient use was conducted. Descriptive analysis, logistic regression, and ordinary least squares (OLS) regression were used to describe the factors associated with the use and cost of allogeneic blood transfusion (ABT). Hospitalization costs were $18,690 (SD=14,159) per patient, erythropoietin costs were $85.25 (SD=3,691.66) per patient, and topical sealant costs were $414.34 (SD=1,020.06) per patient. Sub-analysis of ABT restricted to users revealed ABT costs ranged from $312.24 (SD=543.35) per patient with whole blood to $2,520 (SD=3,033.49) per patient with fresh frozen plasma. Patients that received hypotensive anesthesia (OR,1.61; 95% CI, 1.47–1.77), a volume expander (OR,1.95; 95% CI, 1.75–2.18), autologous blood (OR, 2.04; 95% CI, 1.71–2.42), or an erythropoietic agent (OR=1.64; 95% CI, 1.27–2.12) had a higher risk of ABT. Patients that received cell salvage had a lower risk of transfusion (OR=0.40; 95% CI, 0.32–0.50). Most blood avoidance techniques have low utilization or do not reduce the burden of transfusion associated with spinal fusion.
PMCID: PMC2200697  PMID: 16463198
Spinal fusion surgery; Burden of illness; Blood transfusion; Cost

Results 1-17 (17)