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A M Walker

Publications and source records attributed to A M Walker.

332 records · Page 19Linked to original sources
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Pattern recognition in health insurance claims databases.

Information in claims databases resides in data patterns rather than in data elements. Finding this information requires new terminology, a willingness to pose questions of form rather than specific hypotheses, and a quality control system that elevates the correctness of data relations above the validity of single facts. The language of claims data is a newspeak of CPT (Current Procedural Terminology), HCPCS (Health Care Financing Agency Common Procedure Coding System), ICD (International Classification of Disease), and NDC (National Drug Codes) for pharmaceutical codes. The techniques of pattern discovery are really ways of asking the data for classes of relations, and they vary in their reliance on external information. Sometimes, the question is entirely constrained by preceding factors. Other times we may recast the natural history of disease into a claims context and ask the data to give us the shape of disease evolution. We can use highly automated systems to evaluate the relations between prespecified factors, or empirical techniques to search out common relations that we have not specified in advance. Using massive data sets requires that quality control corresponds to the nature of the high-level information that we derive from large databases.

Databases as Topic↗
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A cost density analysis of benign prostatic hyperplasia.

We assessed the frequency and cost of care for benign prostatic hyperplasia (BPH) among approximately 165,000 subscribers to Fallon Community Health Plan (FCHP), a group model health maintenance organization located in central Massachusetts. We computed rates of episodes of medical services for BPH using automated utilization files, and we estimated costs using Medicare reimbursement schedules and medication average wholesale prices. We identified 3919 men who visited a physician for BPH from January 1, 1991, until December 31, 1994, during which time they contributed 8336 person-years to the analysis. This population comprises approximately 12% of men at least 40 years old at FCHP. From 1991 to 1994, 696 (18%) men received terazosin, 219 (6%) men underwent a prostatectomy, and 41 (1%) men received finasteride. Men averaged 1.66 office visits per year to a physician for BPH. Most office visits (61%) were to a primary care physician, with 39% of the visits to a urologist. Among patients who received terazosin, the frequency of office visits increased slightly after receiving terazosin, from 2.14 to 2.62 visits per year. Among surgery patients, the frequency of visits declined after prostatectomy, from 6.31 visits per year to 1.67 visits. The individual annual cost rate for BPH care ranged from $25.00 to $25,352.00, with an average of $364.00 per person and a median cost of $126.00. The major components of the overall costs were hospital admissions (35%), terazosin dispensings (29%), and physician office visits (19%), with outpatient hospital care and ambulatory procedures accounting for the remaining 17%. Among men receiving terazosin, the average cost was $1190.00 per person-year, and among patients undergoing prostatectomy, the cost was $2630.00 per person-year. The prostatectomy rate declined by nearly 80% during the study period, while the dispensing rate for terazosin doubled, resulting in an overall decline in the total cost of care for BPH from 1991 to 1994.

Adult↗
PubMedDate not supplied

The relationship of bronchopulmonary dysplasia to the occurrence of alveolar rupture during positive pressure ventilation.

The effect of altered mechanical ventilation on the incidence of alveolar rupture and bronchopulmonary dysplasia (BPD) was reviewed in infants who had neonatal respiratory distress syndrome (RDS) (N = 99). From 1971 to 1974 we attempted to minimize pulmonary oxygen exposure. Accordingly, during the resolution of respiratory distress syndrome, the ventilator pressures were not reduced until the FIO2 had been lowered to 0.4 (n = 61). In 1974 to 1975 earlier reduction of pressure was instituted as the FIO2 was lowered to 0.6 or less (N = 38). Birth weight and gestational age were comparable in the two groups. With earlier reduction of ventilator pressures, there was a significant decrease in the duration of exposure to peak inspiratory pressures greater than or equal to 40 cm H2O (p is less than 0.004) and greater than or equal to 50 cm H2O (p is less than 0.002). The incidence of alveolar rupture during postive pressure ventilation fell from 51 to 24% (p is less than 0.015) and bronchopulmonary dysplasia from 41 to 13% (p is less than 0.003). In addition, there was a decrease in the duration of mechanical ventilation (p is less than 0.02) and exposure to an FIO2 is greater than or equal to 0.6 (p = 0.07). The results confirm the intimate relationship of pulmonary barotrauma, as reflected by the occurrence of alveolar rupture during positive pressure inflation of the lungs, to the subsequent development of bronchopulmonary dysplasia and that prevention of the former is associated with a concomitant fall in incidence of the latter.

Follow-Up Studies↗
PubMedDate not supplied

Side effects and sociobehavioral factors associated with the discontinuation of hormone therapy in a Massachusetts health maintenance organization.

OBJECTIVE: To identify sociobehavioral factors and side effects associated with the discontinuation of postmenopausal hormone therapy in a clinical practice setting DESIGN: A total of 816 women aged 45-59 who began hormone therapy between July 1993 and June 1995 in a Massachusetts health maintenance organization were followed for 2 years from the day they received a prescription for estrogen. This cohort has been previously studied for health, treatment, and demographic determinants of hormone therapy discontinuation. In March 1999, these women were mailed a questionnaire containing closed and open-ended questions. A total of 449 women (55%) completed the survey. Discrete-time hazards models were used to identify determinants of discontinuation, controlling for medical predictors of survey nonresponse. RESULTS: Women separated from their partners when they initiated hormone therapy (relative risk [RR] of discontinuation = 3.42; 95% confidence interval [CI] = 1.09, 10.73) and women with a body mass index greater than 29.0 (RR = 1.62; 95% CI = 1.18, 2.23) were more likely to discontinue. Women who had ever used oral contraceptives were less likely to discontinue hormone therapy (RR = 0.70; 95% CI = 0.51, 0.98). After women began using hormone therapy, those who experienced irregular bleeding (RR = 1.58; 95% CI = 1.08, 2.31), edema (RR = 2.18; 95% CI = 1.42, 3.34), or abdominal cramps and pelvic pain (RR = 2.42; 95% CI = 1.46, 4.02) while using hormones were more likely to discontinue. The effect of edema and abdominal cramps on the rate of discontinuation was greatest during the first 6 months of use. Women who adjusted their progestin schedule on their own were four times more likely than other women to discontinue hormones (RR = 4.18; 95% CI = 2.20, 7.94). The use of alternative therapies was not statistically associated with discontinuation. CONCLUSIONS: Women who report therapeutic benefits from hormone therapy are more likely to continue using hormones long-term. The experience of certain side effects, especially during the first few months of hormone use, strongly affects whether women continue using hormone therapy.

Behavior↗