Clinical utility and value contribution of an MRI-positive line marker for image-guided brachytherapy in gynecologic malignancies.

PURPOSE: The purpose of this study was to investigate the utility of a novel MRI-positive line marker, composed of C4:S (cobalt chloride-based contrast agent) encapsulated in high-density polyethylene tubing, in permitting dosimetry and treatment planning directly on MRI. METHODS AND MATERIALS: We evaluated the clinical feasibility of the C4:S line markers in nine sequential brachytherapy procedures for gynecologic malignancies, including six tandem-and-ovoid and three interstitial cases. We then quantified the internal resource utilization of an intraoperative MRI-guided procedural episode via time-driven activity-based costing, identifying opportunities for cost-containment with use of the C4:S line markers. RESULTS: The C4:S line markers demonstrated the strongest positive signal visibility on 3D constructive interference in steady state (CISS)/FIESTA-C followed by T1-weighted sequences, permitting accurate delineation of the applicator lumen and thus the source path. These images may be fused along with traditional T2-weighted sequences for optimal tumor and anatomy contouring, followed by treatment planning directly on MRI. By eliminating postoperative CT for fusion and applicator registration from the procedural episode, use of the C4:S line markers could decrease workflow time and lower total delivery costs per procedure. CONCLUSIONS: This analysis supports the clinical utility and value contribution of the C4:S line markers, which permit accurate MRI-based dosimetry and treatment planning, thereby eliminating the need for postoperative CT for fusion and applicator registration.

Developing an intraoperative 3T MRI-guided brachytherapy program within a diagnostic imaging suite: Methods, process workflow, and value-based analysis.

PURPOSE: We integrated a brachytherapy procedural workflow within an existing diagnostic 3.0-T (3T) MRI suite. This setup facilitates intraoperative MRI guidance for optimal applicator positioning, particularly for interstitial needle placements in gynecologic cases with extensive parametrial involvement. METHODS AND MATERIALS: Here we summarize the multidisciplinary collaboration, equipment, and supplies necessary to implement an intraoperative MRI-guided brachytherapy program; outline the operational workflow via process maps; and address safety precautions. We evaluate internal resource utilization associated with this progressive approach via time-driven activity-based costing methodology, comparing institutional costs to that of a traditional workflow (within a CT suite, followed by separate postprocedure MRI) over a single brachytherapy procedural episode. RESULTS: Resource utilization was only 15% higher for the intraoperative MRI-based workflow, attributable to use of the MRI suite and increased radiologist effort. Personnel expenses were the greatest cost drivers for either workflow, accounting for 76-77% of total resource utilization. However, use of the MRI suite allows for potential cost-shifting opportunities from other resources, such as CT, during the procedural episode. Improvements in process speed can also decrease costs: for each 10% decrease in case duration from baseline procedure time, total costs could decrease by roughly 8%. CONCLUSIONS: This analysis supports the feasibility of an intraoperative MRI-guided brachytherapy program within a diagnostic MRI suite and defines many of the resources required for this procedural workflow. Longer followup will define the full utility of this approach in optimizing the therapeutic ratio for gynecologic cancers, which may translate into lower costs and higher value with time, over a full cycle of care.

Investigation of TLD and EBT3 performance under the presence of 1.5T, 0.35T, and 0T magnetic field strengths in MR/CT visible materials.

PURPOSE: The aim of this study was to investigate thermoluminescent dosimeters (TLD) and radiochromic EBT3 film inside MR/CT visible geometric head and thorax phantoms in the presence of: 0, 0.35, and 1.5 T magnetic fields. METHODS: Thermoluminescent Dosimeters reproducibility studies were examined by irradiating IROC-Houston's TLD acrylic block five times under 0 and 1.5 T configurations of Elekta's Unity system and three times under 0 and 0.35 T configurations of ViewRay's MRIdian Cobalt-60 (60 Co) system. Both systems were irradiated with an equivalent 10 × 10 cm2 field size, and a prescribed dose of 3 Gy to the maximum depth deposition (dmax). EBT3 film and TLDs were investigated using two geometrical Magnetic Resonance (MR)-guided Radiation Therapy (MRgRT) head and thorax phantoms. Each geometrical phantom had eight quadrants that combined to create a centrally located rectangular tumor (3 × 3 × 5 cm3 ) surrounded by tissue to form a 15 × 15 × 15 cm3 cubic phantom. Liquid polyvinyl chloride plastic and Superflab were used to simulate the tumor and surrounding tissue in the head phantom, respectively. Synthetic ballistic gel and a heterogeneous in-house mixture were used to construct the tumor and surrounding tissue in the thorax phantom, respectively. EBT3 and double-loaded TLDs were used in the phantoms to compare beam profiles and point dose measurements with and without magnetic fields. GEANT4 Monte Carlo simulations were performed to validate the detectors for both Unity 0 T/1.5 T and MRIdian 0 T/0.35 T configurations. RESULTS: Average TLD block measurements which, compared the magnetic field effects (magnetic field vs 0 T) on the Unity and MRIdian systems, were 0.5% and 0.6%, respectively. The average ratios between magnetic field effects for the geometric thorax and head phantoms under the Unity system were -0.2% and 1.6% and for the MRIdian system were 0.2% and -0.3%, respectively. Beam profiles generated with both systems agreed with Monte Carlo measurements and previous literature findings. CONCLUSIONS: TLDs and EBT3 film dosimeters could potentially be used in MR/CT visible tissue equivalent phantoms that will experience a magnetic field environment.

Prostate magnetic resonance imaging for brachytherapists: Diagnosis, imaging pitfalls, and post-therapy assessment.

Optimal integration of multiparametric MRI (mp MRI) into prostate brachytherapy practice necessitates an understanding of imaging findings pertinent to prostate cancer detection and staging. This review will summarize prostate cancer imaging findings and tumor staging on mp MRI, including an overview of the Prostate Imaging Reporting and Data System (PIRADS)-structured reporting schema, mp MRI findings observed in the post-therapy setting including cases of post-treatment recurrence, and MRI concepts integral to successful salvage brachytherapy.

Effect of pulse sequence parameter selection on signal strength in positive-contrast MRI markers for MRI-based prostate postimplant assessment.

PURPOSE: For postimplant dosimetric assessment, computed tomography (CT) is commonly used to identify prostate brachytherapy seeds, at the expense of accurate anatomical contouring. Magnetic resonance imaging (MRI) is superior to CT for anatomical delineation, but identification of the negative-contrast seeds is challenging. Positive-contrast MRI markers were proposed to replace spacers to assist seed localization on MRI images. Visualization of these markers under varying scan parameters was investigated. METHODS: To simulate a clinical scenario, a prostate phantom was implanted with 66 markers and 86 seeds, and imaged on a 3.0T MRI scanner using a 3D fast radiofrequency-spoiled gradient recalled echo acquisition with various combinations of scan parameters. Scan parameters, including flip angle, number of excitations, bandwidth, field-of-view, slice thickness, and encoding steps were systematically varied to study their effects on signal, noise, scan time, image resolution, and artifacts. RESULTS: The effects of pulse sequence parameter selection on the marker signal strength and image noise were characterized. The authors also examined the tradeoff between signal-to-noise ratio, scan time, and image artifacts, such as the wraparound artifact, susceptibility artifact, chemical shift artifact, and partial volume averaging artifact. Given reasonable scan time and managable artifacts, the authors recommended scan parameter combinations that can provide robust visualization of the MRI markers. CONCLUSIONS: The recommended MRI pulse sequence protocol allows for consistent visualization of the markers to assist seed localization, potentially enabling MRI-only prostate postimplant dosimetry.

Increasing off-label use of antipsychotic medications in the United States, 1995-2008.

OBJECTIVE: To evaluate patterns of antipsychotic use. DESIGN, SETTING, AND MEASUREMENTS: We used nationally representative data from the IMS Health National Disease and Therapeutic Index to describe outpatient antipsychotic use. The primary outcome was the volume of visits where antipsychotics were used for specific indications (treatment visits). We also quantified use without U.S. Food and Drug Administration approval (off-label use) and off-label use with compendium data suggesting an uncertain evidence base. RESULTS: Antipsychotic use increased from 6.2 million (M) treatment visits (95% CI, 5.4-7.0) in 1995 to 16.7 M visits (15.5-18.2) in 2006, then declined to 14.3 M visits (13.0-15.6) by 2008. A shift occurred from typical agents in 1995 (84% of all antipsychotic visits) to atypical agents by 2008 (93%). As they declined, typical medications shifted toward use in schizophrenia (30% in 1995 to 48% 2008). In contrast, use of atypical agents expanded for bipolar affective disorder (10 to 34%), remained stable for depression (12 to 14%), and declined for schizophrenia (56 to 23%). Overall, antipsychotic use for indications without FDA approval increased from 4.4 M visits in 1995 to 9.0 M in 2008. The estimated cost associated with off-label use in 2008 was US$6.0 billion. CONCLUSIONS: Atypical use has grown far beyond substitution for the now infrequently used typical agents. Antipsychotics are increasingly used for conditions where FDA approval and associated clinical evidence is less certain. Despite the value of innovation, the benefits of widening atypical antipsychotic use should be weighed against their cost, regulatory status, and incomplete nature of available evidence.

Preclinical assessment of a 980-nm diode laser ablation system in a large animal tumor model.

PURPOSE: To characterize the performance of a 980-nm diode laser ablation system in an in vivo tumor model. MATERIALS AND METHODS: This study was approved by the institutional animal care and use committee. The ablation system consisted of a 15-W, 980-nm diode laser, flexible diffusing-tipped fiber optic, and 17-gauge internally cooled catheter. Ten immunosuppressed dogs were inoculated subcutaneously with canine-transmissible venereal tumor fragments in eight dorsal locations. Laser ablations were performed at 79 sites where inoculations were successful (99%) at powers of 10 W, 12.5 W, and 15 W, with exposure times between 60 and 180 seconds. In 20 cases, multiple overlapping ablations were performed. After the dogs were euthanized, the tumors were harvested, sectioned along the applicator tract, measured, and photographed. Measurements of ablation zone were performed on gross specimen. Histopathology and viability staining was performed with hematoxylin and eosin and nicotinamide adenine dinucleotide hydrogen staining. RESULTS: Gross pathologic examination confirmed a well circumscribed ablation zone with sharp boundaries between thermally ablated tumor in the center surrounded by viable tumor tissue. When a single applicator was used, the greatest ablation diameters ranged from 12 mm at the lowest dose (10 W, 60 seconds) to 26 mm at the highest dose (15 W, 180 seconds). Multiple applicators created ablation zones as large as 42 mm in greatest diameter (with the lasers operating at 15 W for 120 seconds). CONCLUSIONS: The new 980-nm diode laser and internally cooled applicator effectively create large ellipsoid thermal ablations in less than 3 minutes.

Magnetic resonance imaging assessment of a convective therapy delivery paradigm in a canine prostate model.

PURPOSE: To quantitatively investigate the feasibility of MRI as a tool for assessing the spatial distribution of a convectively delivered agent using a canine prostate model. MATERIALS AND METHODS: Canine prostates (ex vivo, n = 3; in vivo, n = 12) were injected under several injection paradigms with a solution of gadolinium-DTPA for MR contrast and methylene blue as a grossly visible surrogate drug marker. Ex vivo and in vivo distributions were assessed at 1.5T and quantitatively compared. RESULTS: Measured distributions using MRI and methylene blue pathology photographs were analyzed using a Bland-Altman method. The fractional percentage volume covered (V frac) compared the measurements grossly: Pearson's correlation coefficients were R = 0.99 for ex vivo and R = 0.77 for in vivo (P < 0.05). The fractional percentage of area covered (A frac) demonstrated the high degree of spatial correlation between individual slices: R = 0.93 for ex vivo and R = 0.98 for in vivo (P < 0.05). There was no statistically observable bias in scale or offset between the measurements. CONCLUSION: Measured distributions using MRI and pathology were highly correlated and unbiased, indicating the potential of MRI as a tool for quantitative assessment of interstitial delivery of injected therapies in vivo.

Frequency of infectious gastrointestinal illness in Australia, 2002: regional, seasonal and demographic variation.

To estimate the frequency of infectious gastroenteritis across Australia, and to identify risk factors, we conducted a national telephone survey of 6087 randomly selected respondents in 2001-2002. The case definition was three or more loose stools and/or two or more vomits in a 24-hour period in the last 4 weeks, with adjustment to exclude non-infectious causes and symptoms secondary to a respiratory infection. Frequency data were weighted to the Australian population. Multivariate logistic regression was used to assess potential risk factors including season, region, demographic and socioeconomic status. Among contacted individuals, 67% responded. The case definition applied to 7% of respondents (450/6087) which extrapolates to 17.2 million (95% CI 14.5-19.9 million) cases of gastroenteritis in Australia in one year, or 0.92 (95% CI 0.77-1.06) cases/person per year. In the multivariate model, the odds of having gastroenteritis were increased in summer and in the warmest state, in young children, females, those with higher socioeconomic status and those without health insurance.

Variation in routine electrocardiogram use in academic primary care practice.

BACKGROUND: Lack of practical consensus regarding routine electrocardiogram (ECG) ordering in primary care led us to hypothesize that nonclinical variations in ordering would exist among primary care providers. METHODS: We used 2 computerized billing systems to measure ECG ordering at visits to providers in 10 internal medicine group practices affiliated with a large, urban teaching hospital from October 1, 1996, to September 30, 1997. To focus on screening or routine ECGs, patients with known cardiac disease or suggestive symptoms were excluded, as were providers with fewer than 200 annual patient visits. Included were 69 921 patients making 190 238 visits to 125 primary care providers. Adjusted rates of ECG ordering accounted for patient age, sex, and 5 key diagnoses. Logistic regression evaluated additional predictors of ECG ordering. RESULTS: Electrocardiograms were ordered in 4.4% of visits to patients without reported cardiac disease. Among the 10 group practices, ECG ordering varied from 0.5% to 9.6% of visits (adjusted rates, 0.8%-8.6%). Variations between individual providers were even more dramatic: adjusted rates ranged from 0.0% to 24% of visits, with an interquartile range of 1.4% to 4.7% and a coefficient of variation of 88%. Significant predictors of ECG use were older patient age, male sex, and the presence of clinical comorbidities. Additional nonclinical predictors included Medicare as a payment source, older male providers, and providers who billed for ECG interpretation. CONCLUSIONS: Variations in ECG ordering are not explained by patient characteristics. The tremendous nonclinical variations in ECG test ordering suggest a need for greater consensus about use of screening ECGs in primary care.

The duration of ambulatory visits to physicians.

BACKGROUND: The objective of our study was to determine the typical length of ambulatory visits to a nationally representative sample of primary care physicians, and the patient, physician, practice, and visit characteristics affecting duration of visit. METHODS: We used an analysis of cross-sectional survey data to determine duration of visit and the characteristics associated with it. The data sources were a random sample of the 19,192 visits by adults to 686 primary care physicians contained in the 1991-1992 National Ambulatory Medical Care Survey, and the results of the Physician Induction Interview conducted by the National Center for Health Statistics. Duration of visit was defined as the total time spent in face-to-face contact with the physician. RESULTS: Mean duration of visit was 16.3 minutes (standard deviation = 9.7). Multivariate analysis allowed the calculation of the independent effect on visit length of a variety of characteristics of patients, physicians, organizational/practice setting, geographic location, and visit content. Certain patient characteristics (increasing age and the presence of psychosocial problems) were associated with increased duration of visit. Visit content was also associated with increased duration, including ordering or performing 4 or more diagnostic tests (71% increase), Papanicolaou smears (34%), ambulatory surgical procedures (34%), patient admission to the hospital (32%), and 3 preventive screening tests (25%). Reduced duration of visit was associated with availability of non-physician support personnel and health maintenance organization and Medicaid insurance. CONCLUSIONS: Multiple factors affect duration of visit. Clinicians, policymakers, and health system managers should take these considerations into account in managing physician resources during daily ambulatory practice.

Trends in antihypertensive drug advertising, 1985-1996.

BACKGROUND: Over the past decade, calcium channel blockers (CCBs) and ACE inhibitors have been used increasingly in the treatment of hypertension. In contrast, beta-blocker and diuretic use has decreased. It has been suggested that pharmaceutical marketing has influenced these prescribing patterns. No objective analysis of advertising for antihypertensive therapies exists, however. METHODS AND RESULTS: We reviewed the January, April, July, and October issues of the New England Journal of Medicine from 1985 to 1996 (210 issues). The intensity of drug promotion was measured as the proportion of advertising pages used to promote a given medication. Statistical analyses used the chi2 test for trend. Advertising for CCBs increased from 4.6% of advertising pages in 1985 to 26.9% in 1996, while advertising for beta-blockers (12.4% in 1985 to 0% in 1996) and diuretics (4.2% to 0%) decreased (all P<0.0001). A nonsignificant increase was observed in advertising for ACE inhibitors (3.5% to 4.3%, P=0.17). Although the total number of drug advertising pages per issue decreased from 60 pages in 1985 to 42 pages in 1996 (P<0.001), the number of pages devoted to calcium channel blocker advertisements nearly quadrupled. CONCLUSIONS: Increasing promotion of CCBs has mirrored trends in physician prescribing. An association between advertising and prescribing patterns could explain why CCBs have supplanted better-substantiated therapies for hypertension.

The declining impact of race and insurance status on hormone replacement therapy.

OBJECTIVE: Socioeconomic barriers may limit the adoption of hormone replacement therapy, but little is known about recent trends in their influence. We evaluated trends in the impact of race and insurance status on national rates of hormone replacement therapy. DESIGN: We analyzed 32,608 physician office visits by nonpregnant women 40 years of age and older available from the 1989 through 1996 National Ambulatory Medical Care Surveys. The proportion of visits with new or continuing use of noncontraceptive estrogens reported was the main outcome measured. Multiple logistic regression was used to evaluate the independent effects of year, race, and expected payment source on hormone replacement therapy. RESULTS: Overall, the report of hormone replacement therapy increased from 5.7% of visits in 1989-1990 to 10.9% in 1995-1996. In 1989-1990, hormone replacement therapy was less likely in nonwhite women (3.6% vs. 6.3% for whites) and in women with Medicaid coverage (1.3% vs. 8.4% for privately insured women). These differences diminished over time, particularly for women without menopausal symptoms. In 1989-1990, the adjusted odds ratio of hormone replacement in women without menopausal symptoms was 0.31 (95% confidence interval 0.2-0.5) in nonwhites compared with whites, but increased to 0.57 (0.4-0.8) by 1995-1996. In 1989-1990, the adjusted odds ratio for hormone replacement among women with Medicaid was 0.31 (0.09-1.0) compared with those with private insurance. This ratio increased to 0.86 (0.5-1.4) by 1995-1996. CONCLUSIONS: Racial and payment source influences on hormone replacement therapy appeared to have lessened over time. Despite these changes substantial socioeconomic differences in treatment patterns remain to be addressed.

The impact of cancer on the physical function of the elderly and their utilization of health care.

BACKGROUND: Controversy about whether cancer has an independent impact on patient quality of life led the authors to evaluate the effects of cancer on a range of quality-of-life and health care utilization measures within an elderly population. METHODS: The authors analyzed a nationally representative sample of 9745 elderly community-based Medicare beneficiaries sampled in the 1991 Medicare Current Beneficiary Survey. Of these, 1647 reported being diagnosed by a physician as having a malignancy that was not of the skin. Multiple logistic regression was used to identify the independent predictors of functional limitation, poor health status, health care utilization, and patient satisfaction with medical care. RESULTS: Cancer was reported by 17% of the elderly. Individuals with cancer reported poorer health, more limitations of the activities of daily living (ADLs) and the instrumental activities of daily living (IADLs), and greater health care utilization than individuals without cancer. For individuals with cancer, difficulty walking (38%) and getting out of a chair (21%) were the most commonly reported ADL limitations, whereas difficulty completing heavy housework (34%) and shopping (17%) were the most common IADL limitations. Carcinomas of the lung, prostate, and colon independently predicted poorer health status. Lung carcinoma was independently associated with more ADL limitations. Lung, bladder, and prostate carcinomas predicted increased health care utilization. Overall, cancer patients were at least as satisfied with their medical care as those without cancer. CONCLUSIONS: Cancer increased the use of health care resources and modestly reduced physical function. By identifying specific connections between cancer and physical function, these findings have implications for improving cancer care.

Low rates of hormone replacement in visits to United States primary care physicians.

Our objective was to determine national rates and predictors of hormone replacement therapy. We analyzed a nationally representative sample of 6341 office visits by women aged > or = 40 years to primary care physicians in the 1993 and 1994 National Ambulatory Medical Care Surveys. Independent predictors of estrogen use were determined by logistic regression. Time trends from 1989 through 1994 also were evaluated. Hormone replacement therapy was documented in 4.7% of visits in 1989 to 1990 and 8.0% in 1993 to 1994. In 1993 to 1994 women with menopausal symptoms were six times more likely to have hormone replacement reported. In the absence of symptoms, obstetrician-gynecologists were nearly four times as likely to report hormone replacement therapy. Age 50 to 59 years, white race, osteoporosis, hyperlipidemia, and residence in the West and in nonmetropolitan areas also independently-predicted hormone replacement. Low rates of estrogen therapy by non-obstetrician-gynecologists and substantial practice variations suggest missed opportunities for hormone replacement therapy.

Trends in cesarean section use in California, 1983 to 1990.

OBJECTIVE: Our aim was to assess recent trends in cesarean section use in California. STUDY DESIGN: California discharge abstract data on hospital deliveries in 1983 through 1990 (379,759 to 587,508 annual deliveries) were used to analyze time trends by indication, age, race, and payment source. RESULTS: California cesarean section rates increased annually from 21.8% in 1983 to 25.0% in 1987 and then decreased to 22.7% by 1990. Similar patterns were noted for all age and race or ethnicity groups. Primary cesarean section rates increased from 15.2% in 1983 to 17.9% in 1987, then decreased to 16.2% by 1990. Declines in repeat cesarean section rates continued throughout 1983 through 1990, accelerating after 1987. For both primary and repeat cesarean section rates, time trends after mid-1987 were significantly different than those for 1983 to 1987. CONCLUSION: After increasing from 1983 to 1987, California cesarean section rates declined from 1988 to 1990. Existing payment source differences in cesarean section use increased in magnitude from 1983 to 1990, with privately insured women consistently having the highest cesarean section rates.

The impact of nonclinical factors on repeat cesarean section.

Nonclinical factors, including the setting in which health care takes place, influence clinical decisions. This research measures the independent effects of organizational and socioeconomic factors on repeat cesarean section use in California. Of 45,425 births to women with previous cesarean sections in 1986, vaginal birth after cesarean section occurred in 10.9%. Sizable nonclinical variations were noted. By hospital ownership, rates ranged from 4.9% (for-profit hospitals) to 29.2% (University of California). Variations also existed by hospital teaching level (nonteaching hospitals, 7.0%, vs formalized teaching hospitals, 23.3%); payment source (private insurance, 8.1%, vs indigent services, 25.2%); and obstetric volume (low-volume hospitals, 5.4%, vs high-volume hospitals, 16.6%). Multiple logistic regression demonstrated that these variables had independent effects after accounting for their overlapping influences and the effects of patient characteristics. The observed variations demonstrate the prominence of nonclinical factors in decision making and question the clinical appropriateness of current practice patterns.

Cesarean section use and source of payment: an analysis of California hospital discharge abstracts.

This study assessed the relation between payment source and cesarean section use by analyzing California data on hospital deliveries. Of 461,066 deliveries in 1986, cesarean sections were performed in 24.4 percent. Women with private insurance had the highest cesarean section rates (29.1 percent). Successively lower rates were observed for women covered by non-Kaiser health maintenance organizations (26.8 percent), Medi-Cal (22.9 percent), Kaiser (19.7 percent), self-pay (19.3 percent), and Indigent Services (15.6 percent). Vaginal birth after cesarean (VBAC) occurred more than twice as frequently in women covered by Kaiser (19.9 percent) and Indigent Services (24.8 percent), compared to those with private insurance (8.1 percent). Sizable, although less pronounced, associations between payment source and cesarean section use were noted for the indications of breech presentation, dystocia, and fetal distress. Accounting for maternal age and race/ethnicity did not alter these findings. Variations in the use of cesarean section have a substantial financial impact on health care payors.

Alternative strategies for controlling rising cesarean section rates.

Cesarean section rates in the United States have increased from 5.5% in 1970 to 24.4% in 1987. This dramatic increase has generated considerable concern, leading to a variety of proposals to control rising use of cesarean section. Six strategies have been adopted or proposed to reduce cesarean section use: (1) education and peer evaluation, (2) external review, (3) public dissemination of cesarean section rates, (4) changes in physician payment, (5) changes in hospital payment, and (6) medical malpractice reform. These strategies differ in their specific assumptions regarding the process of clinical decision making, implications for physician autonomy, and methods of implementation. Educational efforts have been the most widely promoted. Of these, formal programs aimed at modifying practices within individual hospitals appear to be the most successful. However, insufficient research has been conducted to compare conclusively the impact and feasibility of these six strategies, pointing to the need for further study.

Socioeconomic differences in rates of cesarean section.

Increasing cesarean-section rates have focused attention on variations in the use of this procedure that appear to be independent of medical indication. We investigated the relation between the rate of primary cesarean section and socioeconomic status in a cohort of 245,854 singleton infants born to non-Hispanic white, black, Asian-American, and Mexican-American residents of Los Angeles County, California. On the basis of birth-certificate data for 1982 and 1983, a significant relation, independent of maternal age, parity, or birth weight, was found between the rates of primary cesarean section and socioeconomic status. Women who lived in census tracts with a median family income of more than $30,000 had a primary cesarean-section rate of 22.9 percent, as compared with 13.2 percent among women residing in areas with a median family income under $11,000. In women between the ages of 18 and 34, the incidence of reported complications of pregnancy or childbirth in the lowest-income group was 10.9 percent, as compared with 17.4 percent in the highest-income group (accounting for 42 percent of the difference in the rate of primary cesarean section between groups); the rate of primary cesarean section in the presence of complications in these two groups was 65.4 percent and 79.3 percent (accounting for 17 percent of the difference); and the primary rate in the absence of reported complications in these two groups was 6.4 percent and 10.5 percent (accounting for 41 percent of the difference). The rates of primary cesarean section were highest among non-Hispanic whites (20.6 percent), intermediate among Asian Americans (19.2 percent) and blacks (18.9 percent), and lowest among Mexican Americans (13.9 percent). Significant socioeconomic differences in these rates were observed in all four groups (P less than 0.01). We conclude that the rates of primary cesarean section vary directly with socioeconomic status and that this association cannot be accounted for by differences in maternal age, parity, birth weight, race, ethnic group, or complications of pregnancy or childbirth.