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Biomedical subjects

K Arnold Chan

Publications and source records attributed to K Arnold Chan.

At least 19 recordsLinked to original sources
PubMed2007

Estimation of the period prevalence of inflammatory bowel disease among nine health plans using computerized diagnoses and outpatient pharmacy dispensings.

BACKGROUND: There are few contemporary estimates of prevalence rates for inflammatory bowel disease (IBD) in diverse North American communities. METHODS: We estimated the period prevalence of IBD for January 1, 1999, through June 30, 2001, among 1.8 million randomly sampled members of nine integrated healthcare organizations in the US using computerized diagnoses and outpatient pharmaceutical dispensing. We also assessed the positive predictive value (PPV) and sensitivities of 1) the case-finding algorithm, and 2) the 30-month sampling period using medical chart review and linkage to a 78-month dataset, respectively. RESULTS: The PPV of the case-finding algorithm was 81% (95% confidence interval [CI], 78-87) and 84% (95% CI, 79-89) in two different organizations. In both, the sensitivity of the optimal algorithm, compared with the most inclusive, exceeded 90%. The sensitivity of the 30-month sampling period compared with 78 months was 61% (95% CI, 57-64) in one organization. Applying a slightly more sensitive case-finding algorithm, the average period prevalence of IBD across the nine organizations, standardized to the age- and gender-distribution of the US population, 2000 census, was 388 cases (95% CI, 378-397) per 100,000 persons (range 209-784 per 100,000; average follow-up 26 months). The prevalence of Crohn's disease, ulcerative colitis, and unspecified IBD was 129, 191, and 69 per 100,000, respectively. CONCLUSIONS: The observed average prevalence was similar to prevalence proportions reported for other North American populations (369-408 per 100,000). Additional research is needed to understand differences in the occurrence of IBD among diverse populations as well as practice variation in diagnosis and treatment of IBD.

Adolescent↗
PubMed2007

Laboratory monitoring of potassium and creatinine in ambulatory patients receiving angiotensin converting enzyme inhibitors and angiotensin receptor blockers.

PURPOSE: Serum potassium and creatinine monitoring is recommended for patients prescribed angiotensin converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB). Much has been written about hyperkalemia associated with these drugs; little is known about laboratory monitoring patterns. The purpose of this retrospective cohort study was to assess creatinine and potassium monitoring and characteristics associated with monitoring among patients dispensed ACEi or ARB. METHODS: This study was conducted in 10 United States health maintenance organizations. Study patients (n = 52 906) were aged 18 or older with dispensings of ACEi or ARB for at least 1 year. Serum potassium and creatinine monitoring were assessed from administrative data and medical records. RESULTS: More than two-thirds (68.4%) of patients received laboratory monitoring. Likelihood of monitoring increased with age (adjusted odds ratio [OR] 2.10; 95% confidence interval [95%CI] 1.93, 2.28 [individuals >or= 80 compared to <50 years]), >9 outpatient visits (OR 1.46; 95%CI 1.39, 1.54), hospitalization (OR 1.15; 95%CI 1.06, 1.25), concomitant medications (potassium [OR 2.01; 95%CI 1.84, 2.20], diuretics [OR 1.54; 95%CI 1.47, 1.61], digoxin [OR 1.15; 95%CI 1.01, 1.30]), and comorbidities (diabetes [OR 1.68; 95%CI 1.61, 1.75], heart failure [OR 1.73; 95%CI 1.57, 1.90], chronic kidney disease [OR 2.95; 95%CI 2.48. 3.51]). CONCLUSIONS: Nearly one-third of patients dispensed ACEi or ARB did not undergo laboratory monitoring at least yearly. Though patients at increased risk of hyperkalemia were more likely to be monitored, many remained unmonitored.

Adult↗
PubMed2007

Risk factors for statin-associated rhabdomyolysis.

PURPOSE: To identify and characterize risk factors for rhabdomyolysis in patients prescribed statin monotherapy or statin plus fibrate therapy. METHODS: A nested case-control study was conducted within a cohort of 252,460 new users of lipid-lowering medications across 11 geographically dispersed U.S. health plans. Twenty-one cases of rhabdomyolysis confirmed by medical record review were compared to 200 individually matched controls without rhabdomyolysis. A conditional logistic regression model was applied to evaluate the effects of age, gender, comorbidities, concurrent medication use, dosage, and duration of statin use on the development of rhabdomyolysis. RESULTS: Statin users 65 years of age and older have four times the risk of hospitalization for rhabdomyolysis than those under age 65 (odds ratio (OR) = 4.36, 95% confidence interval (CI): 1.5,14.1). We also observed a joint effect of high statin dosage and renal disease (p = 0.022). When these two variables were added to the model with age, we obtained an OR of 5.73 for dosage (95%CI: 0.63, 52.6) and 6.26 for renal disease (95%CI: 0.46, 63.38). Although not statistically significant, we did observe a greater than twofold increase in risk for rhabdomyolysis among females (OR = 2.53, 95%CI: 0.91, 7.32). CONCLUSIONS: Findings of this study indicate that older age is a risk factor for rhabdomyolysis among statin users. Although the evidence is not as strong, high statin dosage, renal disease, and female gender may be additional risk factors. Patients at higher risk of developing rhabdomyolysis should be closely monitored for signs and symptoms of the disease.

Adult↗
PubMed2007

Asthma drug use and the development of Churg-Strauss syndrome (CSS).

PURPOSE: Case reports suggest that leukotriene modifier use may be associated with the onset of Churg-Strauss syndrome (CSS). Using pooled data from two nested case-control studies, we examined the association between asthma drug use and the development of CSS. METHODS: The study was performed in three US managed care organizations and a US national health plan with chart access and complete electronic pharmacy data, with a covered population of 13.9 million. There were 47 cases of possible or definite CSS and 4700 asthma drug user controls identified between January 1, 1995 and December 31, 2002. We examined exposure to asthma drugs in cases and controls, including leukotriene modifiers (6 cases and 202 controls), in the two to 6 months prior to the onset of adjudicated CSS. RESULTS: While the crude association between use of leukotriene modifiers and CSS was strong (odds ratio (OR) 4.00, 95% confidence interval (CI): 1.49-10.60), in a multivariable analysis controlling for use of oral corticosteroids, inhaled corticosteroids, and number of categories of asthma drugs dispensed, there was no significant association (OR 1.32, 95% CI: 0.44-3.96). Use of inhaled and oral corticosteroids, evaluated as markers of asthma severity, were associated with CSS (OR 3.07, 95% CI: 1.34-7.03 and OR 5.36, 95% CI: 2.51-11.45, respectively). CONCLUSIONS: No association was found between CSS and leukotriene modifiers after controlling for asthma drug use However, it is not possible to rule out modest associations with asthma treatments given CSS is so rare and so highly correlated with asthma severity, suggesting further investigation is warranted.

Adolescent↗
PubMed2006

Variation in hepatitis B immunization coverage rates associated with provider practices after the temporary suspension of the birth dose.

BACKGROUND: In 1999, the American Academy of Pediatrics and U.S. Public Health Service recommended suspending the birth dose of hepatitis B vaccine due to concerns about potential mercury exposure. A previous report found that overall national hepatitis B vaccination coverage rates decreased in association with the suspension. It is unknown whether this underimmunization occurred uniformly or was associated with how providers changed their practices for the timing of hepatitis B vaccine doses. We evaluate the impact of the birth dose suspension on underimmunization for the hepatitis B vaccine series among 24-month-olds in five large provider groups and describe provider practices potentially associated with underimmunization following the suspension. METHODS: Retrospective cohort study of children enrolled in five large provider groups in the United States (A-E). Logistic regression was used to evaluate the association between the birth dose suspension and a child's probability of being underimmunized at 24 months for the hepatitis B vaccine series. RESULTS: Prior to July 1999, the percent of children who received a hepatitis B vaccination at birth varied widely (3% to 90%) across the five provider groups. After the national recommendation to suspend the hepatitis B birth dose, the percent of children who received a hepatitis B vaccination at birth decreased in all provider groups, and this trend persisted after the policy was reversed. The most substantial decreases were observed in the two provider groups that shifted the first hepatitis B dose from birth to 5-6 months of age. Accounting for temporal trend, children in these two provider groups were significantly more likely to be underimmunized for the hepatitis B series at 24 months of age if they were in the birth dose suspension cohort compared with baseline (Group D OR 2.7, 95% CI 1.7-4.4; Group E OR 3.1, 95% CI 2.3-4.2). This represented 6% more children in Group D and 9% more children in Group E who were underimmunized in the suspension cohort compared with baseline. Children in the reversal cohort in these groups remained significantly more likely to be underimmunized compared with baseline. In contrast, in a third provider group where the typical timing of the third dose was unchanged and in two other provider groups whose hepatitis B vaccination schedules were unaffected by the birth dose suspension, hepatitis B vaccination coverage either was maintained or improved. CONCLUSION: When the hepatitis B birth dose was suspended, provider groups that moved the first dose of vaccination to 5-6 months of age or later had decreases in hepatitis B vaccine coverage at 24 months. These findings suggest that as vaccine policy changes occur, providers could attempt to minimize underimmunization by adopting vaccination schedules that minimize delays in the recommended timing of vaccine doses.

Cohort Studies↗
PubMed2006

Use of nonsteroidal antiinflammatory drugs and non-Hodgkin lymphoma: a population-based case-control study.

The association between long-term use of nonsteroidal antiinflammatory drugs (NSAIDs) and non-Hodgkin lymphoma (NHL) was examined using data collected between October 2001 and May 2004 in an ongoing population-based case-control study in the San Francisco Bay Area. NHL cases were identified using rapid case ascertainment and Surveillance, Epidemiology, and End Results registry data. Control participants were frequency-matched to cases by age, sex, and county of residence. Participants completed in-person interviews designed to measure potential NHL risk factors. Questions were asked regarding use during the past 20 years of aspirin, prescription and over-the-counter nonselective NSAIDs, and cyclooxygenase-2 (COX-2) inhibitors. A total of 1,000 cases and 1,060 controls contributed data for these interim analyses. Analyses were carried out for men and women and for both sexes combined. After adjustment for age and sex, there was no consistent association between long-term use and NHL for all NSAIDs combined, aspirin, nonselective NSAIDs, and COX-2 inhibitors. For women, long-term aspirin use may be associated with a decreased risk of NHL (for 3-<9 years of use, odds ratio=0.41, 95% confidence interval: 0.18, 0.94). Conversely, although the confidence intervals were wide, the adjusted odds ratios for COX-2 inhibitor use were nearly twofold for women, indicating a possible increase in NHL risk associated with regular use of COX-2 inhibitors.

Adult↗
PubMed2006

Frequency of serum creatinine monitoring during allopurinol therapy in ambulatory patients.

BACKGROUND: Allopurinol dosage reduction is recommended in patients with renal dysfunction because drug toxicity risk is increased. Little information is available about serum creatinine (SCr) monitoring in ambulatory patients taking allopurinol. OBJECTIVE: To evaluate SCr monitoring among patients prescribed allopurinol, identify associated factors, and evaluate administrative data in assessing monitoring. METHODS: Information for this retrospective cohort study was drawn from a dataset of 2 020 037 individuals; approximately 200 000 members from each of 10 organizations. Study patients had received at least one year of ongoing allopurinol prescription dispensings. Patient variables analyzed included age, gender, chronic diseases, outpatient visits, hospitalizations, gout diagnosis, and SCr monitoring. A random sample of medical records was reviewed to assess the accuracy of the automated data. Statistical analysis included descriptive and logistic regression techniques. RESULTS: Overall, 1139 (26%) of 4357 patients did not have SCr monitoring. For individuals without recent hospitalization, factors protective against lack of monitoring were increasing age (OR 0.77 per 10 y; 95% CI 0.74 to 0.79), more chronic diseases (OR 0.81; 95% CI 0.78 to 0.83), more outpatient visits (OR 0.87 per 5 visits; 95% CI 0.83 to 0.91), and gout diagnosis (OR 0.74; 95% CI 0.65 to 0.85). The sensitivity and specificity of administrative data compared with medical records for SCr monitoring were 92% and 65%, respectively. CONCLUSIONS: More than one-fourth of patients dispensed allopurinol did not have SCr monitoring during one year of therapy. Lack of monitoring and lack of subsequent possible dosage adjustment put patients at increased risk of allopurinol toxicity.

Adolescent↗
PubMed2006

Frequency of high-risk use of QT-prolonging medications.

PURPOSE: Prolongation of the QT interval has been associated with increased risk of torsades de pointes and death. Concurrent use of more than one QT-prolonging drug or a QT-prolonging drug with a drug that alters its pharmacokinetic profile is an important risk factor for adverse outcomes. METHODS: Using a representative sample of 2 million health plan members from 10 health maintenance organizations with pharmacy benefits between January 1999 and July 2001, we identified potential drug interactions involving QT-prolonging medications. Prescription claims overlapping by at least 7 days for either 2 or more QT-prolonging drugs or a QT-prolonging drug with a drug that alters its clearance were considered potential drug interactions. We determined the number of drug interactions overall and the number of these interactions involving patients with other risk factors for torsades de pointes. RESULTS: A total of 48 465 potential drug interactions were identified in 10 415 (4.6%) of the 228 550 patients with at least one prescription for a QT-prolonging drug. Amitriptyline was involved in 37 859 (78.1%) of the drug interactions. Of all potential drug interactions, 43 689 (90.1%) occurred in patients with at least one other risk factor for torsades de pointes, and 1053 (2.2%) were listed as a contraindicated combination in product labeling. CONCLUSION: Potential drug interactions involving currently marketed QT-prolonging drugs occurred in 4.6% of patients who had a prescription for a QT-prolonging medication. The findings suggest several areas for targeted interventions to decrease the potential risk from QT-prolonging medications.

Age Factors↗
PubMed2006

FDA drug prescribing warnings: is the black box half empty or half full?

PURPOSE: Black box warnings (BBWs) are the Food and Drug Administration's (FDA) strongest labeling requirements for high-risk medicines. It is unknown how frequently physicians prescribe BBW drugs and whether they do so in compliance with the warnings. The purpose of the present study was to assess the frequency of use of BBW medications in ambulatory care and prescribing compliance with BBW recommendations. METHODS: This retrospective study used automated claims data of 929 958 enrollees in 10 geographically diverse health plans in the United States to estimate frequency of use in ambulatory care of 216 BBW drugs/drug groups between 1/1/99 and 31/6/01. We assessed dispensing compliance with the BBW requirements for selected drugs. RESULTS: During a 30-month period, more than 40% of enrollees received at least one medication that carried a BBW that could potentially apply to them. We found few instances of prescribing during pregnancy of BBW drugs absolutely contra-indicated in pregnancy. There was almost no co-prescribing of contra-indicated drugs with the two QT-interval-prolonging BBW drugs evaluated. Most non-compliance occurred with recommendations for baseline laboratory monitoring (49.6% of all therapy initiations that should have been accompanied by baseline laboratory monitoring were not). CONCLUSIONS: Many individuals receive drugs considered to carry the potential for serious risk. For some of these drugs, use is largely consistent with their BBW, while for others it is not. Since it will not be possible to avoid certain drug- associated risks, it will be important to develop effective methods to use BBWs and other methods to minimize risks.

Adolescent↗
PubMed2006

Methods for evaluation of medication adherence and persistence using automated databases.

PURPOSE: Our aim was to perform a systematic review of the methods currently being used to assess adherence and persistence in pharmacoepidemiological and pharmacoeconomic studies using automated databases. METHODS: A MEDLINE search of English language literature was performed to identify studies published between January 1, 1980 and March 31, 2004 that evaluated adherence, compliance, persistence, switching, or discontinuations of medications using automated dispensing data (pharmacy records). Two study investigators independently reviewed the abstracts and articles to determine relevant studies according to specified criteria. RESULTS: A total of 136 articles met the criteria for evaluation. The types of measures of adherence and persistence commonly reported include the medication possession ratio and related measures of medication availability (77 studies), discontinuation/continuation (58 studies), switching (34 studies), medication gaps (13 studies), refill compliance (7 studies), and retentiveness/turbulence (4 studies). Specific issues considered include the assessment of exposed time to drug therapy and specification of the follow-up period. CONCLUSIONS: The terminology, definitions, and methods to determine adherence and persistence differ greatly in the published literature. The appropriateness and choice of the specific measure employed should be determined by the overall goals of the study, as well as the relative advantages and limitations of the measures.

Databases, Factual↗
PubMed2006

Use of prescription medications with a potential for fetal harm among pregnant women.

PURPOSE: To estimate the prevalence of use of prescription drugs with a potential for fetal harm among pregnant women in the United States. METHODS: A retrospective study was conducted using the automated databases of eight health maintenance organizations involved in the HMO Research Network Center for Education and Research on Therapeutics (CERT). Women who delivered an infant from January 1996 to December 2000 were identified. The frequency of use of prescription drugs with a potential for fetal harm was based upon the expert review of a clinical teratologist and the U.S. Food and Drug Administration (FDA) risk classification system, assuming a gestational duration of 270 days. RESULTS: Among the 114 165 women with no documentation of a diagnosis suggesting potential pre-term birth or dispensing of ovulation stimulants in the 270 days before delivery, 1305 (1.1%) received a teratogenic drug during the 270 days before delivery, based upon the expert review of a clinical teratologist. A larger proportion of women received U.S. FDA category D or X drugs (5.8%; N = 6600). However, the general patterns of use were similar, with higher use in early pregnancy compared to later trimesters. The proportion of women dispensed a teratogen during pregnancy was substantially higher among women who received a teratogen in the 90 days before pregnancy compared to women who did not (adjusted RR = 38.9, 95%CI, 33.5, 45.3). CONCLUSIONS: Our results suggest that further efforts directed at physicians to counsel women or at the women themselves about the potential risks of particular medications appear warranted.

Drug Prescriptions↗
PubMed2006

Potential drug-drug interactions in the outpatient setting.

BACKGROUND: Although medication safety research has tended to focus on inpatients, the safety of drug use among outpatients is also a concern. OBJECTIVE: We estimate the frequency of potentially interacting concomitant medication dispensing among outpatients. RESEARCH DESIGN: We report the number and percent of patients annually dispensed an object drug of interest (ie, warfarin, digoxin, cyclosporine, or lovastatin/simvastatin) with a potentially interacting drug among a random sample of insured adults receiving care from 10 integrated delivery systems. We use 2 definitions of concomitant dispensing: medications dispensed: 1) during the time period for which the patient had the other medication available ('days supply') and 2) on the same day. We also estimate the number of insured U.S. population codispensed these medication pairs. RESULTS: Among patients dispensed a drug of interest, between 17.8% (95% confidence interval [CI]=17.1-18.6%) and 28.0% (95% CI=24.0-32.1%) were concomitantly dispensed a potentially interacting drug using the "days supply" definition, and between 7.1% (95% CI=6.6-7.7%) and 17.7% (95% CI=14.4-21.1%) using the "same day" definition. Extrapolating to the insured U.S. population, between 1.29 (95% CI=1.25-1.33; same day) and 2.67 (95% CI=2.62-2.72; days supply) million insured adults are dispensed 1 of these 4 potentially interacting pairs. CONCLUSIONS: We found evidence of potentially interacting concomitant medication dispensing among outpatients. An opportunity exists to better understand how such dispensing translates into adverse events and ultimately to improved medication safety.

Aged↗
PubMed2006

Monitoring of drugs with a narrow therapeutic range in ambulatory care.

OBJECTIVES: To describe the proportion of patients receiving drugs with a narrow therapeutic range who lacked serum drug concentration monitoring during a 1-year period of therapy and to identify patient characteristics associated with lack of monitoring. STUDY DESIGN: Retrospective cohort. METHODS: Ambulatory patients (n = 17,748) at 10 health maintenance organizations who were receiving ongoing continuous drug therapy with digoxin, carbamazepine, divalproex sodium, lithium carbonate, lithium citrate, phenobarbital sodium, phenytoin, phenytoin sodium, primidone, quinidine gluconate, quinidine sulfate, procainamide hydrochloride, theophylline, theophylline sodium glycinate, tacrolimus, or cyclosporine for at least 12 months between January 1, 1999, and June 30, 2001, were identified. Serum drug concentration monitoring was assessed from administrative data and from medical record data. RESULTS: Fifty percent or more of patients receiving digoxin, theophylline, procainamide, quinidine, or primidone were not monitored, and 25% to 50% of patients receiving divalproex, carbamazepine, phenobarbital, phenytoin, or tacrolimus were not monitored. Younger age was associated with lack of monitoring for patients prescribed digoxin (adjusted odds ratio, 1.86; 95% confidence interval, 1.39-2.48) and theophylline (adjusted odds ratio, 1.58; 95% confidence interval, 1.23-2.04), while older age was associated with lack of monitoring for patients prescribed carbamazepine (adjusted odds ratio, 0.59; 95% confidence interval, 0.44-0.80) and divalproex (adjusted odds ratio, 0.50; 95% confidence interval, 0.38-0.66). Patients with fewer outpatient visits were also less likely to be monitored (P < .001). CONCLUSIONS: A substantial proportion of ambulatory patients receiving drugs with narrow intervals between doses resulting in beneficial and adverse effects did not have serum drug concentration monitoring during 1 year of use. Clinical implications of this finding need to be evaluated.

Ambulatory Care↗
PubMed2005

Results of multivariable logistic regression, propensity matching, propensity adjustment, and propensity-based weighting under conditions of nonuniform effect.

Observational studies often provide the only available information about treatment effects. Control of confounding, however, remains challenging. The authors compared five methods for evaluating the effect of tissue plasminogen activator on death among 6,269 ischemic stroke patients registered in a German stroke registry: multivariable logistic regression, propensity score-matched analysis, regression adjustment with the propensity score, and two propensity score-based weighted methods-one estimating the treatment effect in the entire study population (inverse-probability-of-treatment weights), another in the treated population (standardized-mortality-ratio weights). Between 2000 and 2001, 212 patients received tissue plasminogen activator. The crude odds ratio between tissue plasminogen activator and death was 3.35 (95% confidence interval: 2.28, 4.91). The adjusted odds ratio depended strongly on the adjustment method, ranging from 1.11 (95% confidence interval: 0.67, 1.84) for the standardized-mortality-ratio weighted to 10.77 (95% confidence interval: 2.47, 47.04) for the inverse-probability-of-treatment-weighted analysis. For treated patients with a low propensity score, risks of dying were high. Exclusion of patients with a propensity score of <5% yielded comparable odds ratios of approximately 1 for all methods. High levels of nonuniform treatment effect render summary estimates very sensitive to the weighting system explicit or implicit in an adjustment technique. Researchers need to be clear about the population for which an overall treatment estimate is most suitable.

Aged↗
PubMed2005

Impact of the introduction of pneumococcal conjugate vaccine on immunization coverage among infants.

BACKGROUND: The introduction of pneumococcal conjugate vaccine (PCV) to the U.S. recommended childhood immunization schedule in the year 2000 added three injections to the number of vaccinations a child is expected to receive during the first year of life. Surveys have suggested that the addition of PCV has led some immunization providers to move other routine childhood vaccinations to later ages, which could increase the possibility of missing these vaccines. The purpose of this study was to evaluate whether introduction of PCV affected immunization coverage for recommended childhood vaccinations among 13-month olds in four large provider groups. METHODS: In this retrospective cohort study, we analyzed computerized data on vaccinations for 33,319 children in four large provider groups before and after the introduction of PCV. The primary outcome was whether the child was up to date for all non-PCV recommended vaccinations at 13 months of age. Logistic regression was used to evaluate the association between PCV introduction and the primary outcome. The secondary outcome was the number of days spent underimmunized by 13 months. The association between PCV introduction and the secondary outcome was evaluated using a two-part modelling approach using logistic and negative binomial regression. RESULTS: Overall, 93% of children were up-to-date at 13 months, and 70% received all non-PCV vaccinations without any delay. Among the entire study population, immunization coverage was maintained or slightly increased from the pre-PCV to post-PCV periods. After multivariate adjustment, children born after PCV entered routine use were less likely to be up-to-date at 13 months in one provider group (Group C: OR = 0.5; 95% CI: 0.3-0.8) and were less likely to have received all vaccine doses without any delay in two Groups (Group B: OR = 0.4, 95% CI: 0.3 - 0.6; Group C: OR = 0.5, 95% CI: 0.4-0.7). This represented 3% fewer children in Group C who were up-to-date and 14% (Group C) to 16% (Group B) fewer children who spent no time underimmunized at 13 months after PCV entered routine use compared to the pre-PCV baseline. Some disruptions in immunization delivery were also observed concurrent with temporary recommendations to suspend the birth dose of hepatitis B vaccine, preceding the introduction of PCV. CONCLUSION: These findings suggest that the introduction of PCV did not harm overall immunization coverage rates in populations with good access to primary care. However, we did observe some disruptions in the timely delivery of other vaccines coincident with the introduction of PCV and the suspension of the birth dose of hepatitis B vaccine. This study highlights the need for continued vigilance in coming years as the U.S. introduces new childhood vaccines and policies that may change the timing of existing vaccines.

Cohort Studies↗
PubMed2005

Health plan administrative databases can efficiently identify serious myopathy and rhabdomyolysis.

OBJECTIVE: We evaluated the positive predictive values (PPVs) of specific criteria based upon International Classification of Diseases, 9th revision (ICD-9-CM) codes documented in health plan administrative databases for identification of cases of serious myopathy and rhabdomyolysis. STUDY DESIGN AND SETTING: We conducted a retrospective study among patients enrolled in 11 geographically dispersed managed care organizations. Cohorts of new users of specific statins and fibrates were identified by selecting patients with an initial dispensing of the drug during the period 1 January 1998 to 30 June 2001. Potential cases of serious myopathy or rhabdomyolysis were identified using specific criteria based upon ICD-9-CM codes suggesting a muscle disorder or acute renal failure. RESULTS: A total of 194 hospitalizations meeting the criteria for chart review selection were identified among 206,732 new users of statins and 15,485 new users of fibrates. Overall, 31 cases of serious, clinically important myopathy or rhabdomyolysis (18%) were confirmed through chart review. Of these, 26 (84%) had a claim including codes for myoglobinuria (ICD-9-CM 791.3) or other disorders of muscle, ligament, and fascia (ICD-9-CM 728.89). A PPV of 74% (26 of 35 patients meeting criteria) was found for a composite definition that included (1) a primary or secondary discharge code for myoglobinuria, (2) a primary code for "other disorders of muscle," or (3) a secondary code for "other disorders of muscle" accompanied by a claim for a CK test within 7 days of hospitalization or a discharge code for acute renal failure. CONCLUSION: For rare adverse events such as serious myopathy or rhabdomyolysis, large population-based databases that include diagnosis and laboratory test claims data can facilitate epidemiologic research.

Data Interpretation, Statistical↗
PubMed2005

Changes in women's use of hormones after the Women's Health Initiative estrogen and progestin trial by race, education, and income.

BACKGROUND: We examined the impact of race, education, and household income on changes in rates of discontinuation and initiation of hormone therapy before and after release of the Women's Health Initiative estrogen plus progestin trial results. METHODS: We conducted an observational cohort study of 221 378 women aged 40-80 years enrolled in five health maintenance organizations to estimate the prevalence and rates of discontinuation and initiation of estrogen plus progestin and estrogen only between September 1, 1999, to June 31, 2002 (baseline), and December 31, 2002 (follow-up). We identified the census block group for each participant by geocoding her 2003 residential address. We categorized women into racial, education, and income groups based on the distribution of these characteristics in her community from year 2000 census data and the distributions of these characteristics within her HMO. RESULTS: There were significant differences in estrogen plus progestin and estrogen only prevalence by race, education level, and household income, and in estrogen plus progestin initiation by race and education level, but not by household income at follow-up. However, there were no differences by community race, education, or household income in change in the prevalence of either hormone therapy use at follow-up or in the rates of hormone therapy discontinuation or initiation from baseline to follow-up. CONCLUSIONS: Given the wide spread media attention to the Women's Health Initiative estrogen plus progestin trial results, our findings suggest comparable dissemination of this information across diverse socioeconomic groups.

Adult↗