Factors associated with conversion from laparoscopic to open colectomy using the National Surgical Quality Improvement Program (NSQIP) database.

AIM: Conversion rates from laparoscopic to open colectomy and associated factors are traditionally reported in clinical trials or reviews of outcomes from experienced institutions. Indications and selection criteria for laparoscopic colectomy may be more narrowly defined in these circumstances. With the increased adoption of laparoscopy, conversion rates using national data need to be closely examined. The purpose of this study was to use data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) to identify factors associated with conversion of laparoscopic to open colectomy at a national scale in the United States. METHOD: The ACS-NSQIP Participant Use Data Files for 2006-2011 were used to identify patients who had undergone laparoscopic colectomy. Converted cases were identified using open colectomy as the primary procedure and laparoscopic colectomy as 'other procedure'. Preoperative variables were identified and statistics were calculated using sas version 9.3. Logistic regression was used to model the multivariate relationship between patient variables and conversion status. RESULTS: Laparoscopy was successfully performed in 41 585 patients, of whom 2508 (5.8%) required conversion to an open procedure. On univariate analysis the following factors were significant: age, body mass index (BMI), American Society of Anesthesiologists (ASA) class, presence of diabetes, smoking, chronic obstructive pulmonary disease, ascites, stroke, weight loss and chemotherapy (P < 0.05). The following factors remained significant on multivariate analysis: age, BMI, ASA class, smoking, ascites and weight loss. CONCLUSION: Multiple significant factors for conversion from laparoscopic to open colectomy were identified. A novel finding was the increased risk of conversion for underweight patients. As laparoscopic colectomy is become increasingly utilized, factors predictive of conversion to open procedures should be sought via large national cohorts.

Radium-226 and radon-222: concentration in atlantic and pacific oceans.

Measurements of radon-222 in seawater suggest the following. The radium-226 content of surface water in both the Atlantic and Pacific oceans is uniformly close to about 4 x 10(-14) gram per liter. The deep Pacific has a concentration of radium-226 that is four times higher and the deep Atlantic a concentration twice as high as that of the surface. These distribution profiles can be explained by the same particle-settling rate for radium-226 from surface to depth for the two oceans and by a threefold longer residence time of water in the deep Pacific than in the deep Atlantic. The vertical distribution of the deficiency of radon-222 in the surface water of the northwest Pacific Ocean suggests a coefficient of vertical eddy diffusion as high as 120 square centimeters per second and a gas-exchange rate for carbon dioxide in surface water between 14 and 60 moles per square meter per year. Vertical profiles of the excess of radon-222 in near-bottom water of the South Atlantic give coefficients of vertical eddy diffusion ranging from 1.5 to more than 50 square centimeters per second.

WY14,643, a PPARalpha ligand, attenuates expression of anti-glomerular basement membrane disease.

Peroxisome proliferator-activated receptor alpha (PPARalpha) ligands are medications used to treat hyperlipidaemia and atherosclerosis. Increasing evidence suggests that these agents are immunosuppressive. In the following studies we demonstrate that WY14,643, a PPARalpha ligand, attenuates expression of anti-glomerular basement membrane disease (AGBMD). C57BL/6 mice were fed 0.05% WY14,643 or control food and immunized with the non-collagenous domain of the alpha3 chain of Type IV collagen [alpha3(IV) NC1] in complete Freund's adjuvant (CFA). WY14,643 reduced proteinuria and greatly improved glomerular and tubulo-interstitial lesions. However, the PPARalpha ligand did not alter the extent of IgG-binding to the GBM. Immunohistochemical studies revealed that the prominent tubulo-interstitial infiltrates in the control-fed mice consisted predominately of F4/80(+) macrophages and WY14,643-feeding decreased significantly the number of renal macrophages. The synthetic PPARalpha ligand also reduced significantly expression of the chemokine, monocyte chemoattractant protein (MCP)-1/CCL2. Sera from mice immunized with AGBMD were also evaluated for antigen-specific IgGs. There was a significant increase in the IgG1 : IgG2c ratio and a decline in the intrarenal and splenocyte interferon (IFN)-gamma mRNA expression in the WY14,643-fed mice, suggesting that the PPARalpha ligand could skew the immune response to a less inflammatory T helper 2-type of response. These studies suggest that PPARalpha ligands may be a novel treatment for inflammatory renal disease.

17Beta-estradiol modulates gastroduodenal preneoplastic alterations in rats exposed to the carcinogen N-methyl-N'-nitro-nitrosoguanidine.

Gastric cancers are a significant cause of morbidity worldwide. Epidemiological studies and animal models show that males have higher incidences of gastric cancers compared with females, suggesting that sex hormones may modulate gastric cancer risk. An animal model of the initiation phase of gastric cancer was used to determine the effects of systemic estrogen administration on morphological progression of preneoplastic lesions and to define cell populations at which estrogens may act. Preneoplastic progression in antral and duodenal mucosa was examined in male rats that received the chemical carcinogen, N-methyl-N'-nitro-nitrosoguanidine (MNNG), during treatment with implants containing 17beta-estradiol or oil vehicle. Histopathological changes in antral and duodenal gland morphology, numbers of proliferating cells and apoptotic bodies, and antral gastrin cell numbers and protein storage levels were determined 4 weeks later. With MNNG treatment, duodenal villous heights were significantly decreased, and epithelial cells displayed histological features of hyperplasia and dysplasia. Antral glands showed epithelial hyperplasia and dysplasia, increased mucosal height, and decreased mucin levels. Antral gastrin storage protein levels were decreased by MNNG. Systemic treatment with 17beta-estradiol significantly reversed MNNG-induced alterations in duodenal gland heights while increasing mucin and gastrin levels in antral glands. Cell proliferation and apoptosis rates were not significantly different between groups. The present results indicate that systemic 17beta-estradiol treatment influences antral and duodenal gland differentiation during the initiation phase of chemical gastroduodenal carcinogenesis in male rats. These results explain, in part, a potential pathway through which protective effects of estrogens on chemical carcinogenesis are mediated in the upper gastrointestinal tract.

Medicaid participation by psychiatrists in private practice.

Using national survey data, the authors examined the characteristics of psychiatrists in private practice who treat Medicaid patients. They found that the average Medicaid participation rate was 8%; 39.9% of psychiatrists did not see any Medicaid patients. Participating psychiatrists were more likely to be foreign medical graduates and to have a hospital-oriented practice. Psychiatrists with large Medicaid practices saw significantly more patients per week but spent less time with them. These psychiatrists were also disproportionately located in the West. The authors conclude that these variations are a result of state program differences in Medicaid reimbursement and eligibility policies.

Prolongation of cardiac xenograft survival by depletion of complement.

Complement (C) activation is thought to be critical for the hyperacute rejection of xenografts. We investigated the role of C in the rejection of discordant cardiac xenografts by studying outcome in recipients depleted of C, using a highly purified form of cobra venom factor (CVF) in both a small (guinea pig [GP]-to-rat) and large (pig-to-baboon) animal model. A single dose of 30 or 60 units CVF given i.v. to rats completely abrogated hemolytic C activity for up to 72 hr. The lack of hemolytic C activity correlated with nearly undetectable serum levels of C3. Doses of 30 U/kg daily or 60 U/kg every other day over a 7-day period sustained C depletion without morbidity or mortality. Rats receiving GP cardiac xenografts during CVF therapy had significantly prolonged xenograft survival (88 +/- 10 hr in CVF-treated rats vs. 18.6 +/- 7.2 min in control rats, P < 0.001). Rats that rejected GP xenografts at 4 days posttransplant had higher levels of anti-GP antibodies than control rats, without hemolytic C activity at rejection. This rise in xenoreactive Ig reflected an increase in circulating IgG and IgM against GP antigens recognized before transplantation. Histologic analysis of GP cardiac xenografts taken from CVF-treated rats revealed leukocyte and monocyte margination along blood vessels, beginning at 12 hr posttransplant. Progressive cell infiltration, interstitial hemorrhage, and necrosis were observed over the next 72 hr. Rejected GP xenografts showed diffuse deposition of IgM and fibrin within blood vessels but no evidence of C3 deposition. A nonspecific pattern of IgG deposition was noted. CVF was tested in baboons. Complete C depletion was achieved with a dose of 60 U/kg, and was not associated with any morbidity or mortality. Xenotransplantation of a pig heart was performed in one baboon receiving CVF, 60 U/kg/day, for 2 consecutive days. Xenograft survival was prolonged to 68 hr, compared with 90 +/- 30 min in control baboons. Lack of hemolytic activity was noted during engraftment and at rejection. Histology showed evidence of vascular rejection. Immunopathology showed diffuse deposition of IgM, fibrin, and C4, and absence of C3 or membrane attack complex. We conclude that highly purified CVF can achieve marked C depletion with minimal morbidity and no associated fatalities. CVF alone can significantly prolong discordant cardiac xenograft survival. In the GP-to-rat model, the improvement in graft survival achieved with CVF was better than with conventional immunosuppression or isolated acute antibody depletion.(ABSTRACT TRUNCATED AT 400 WORDS)

Prolongation of renal allograft survival in a large animal model by oral rapamycin monotherapy.

We assessed the efficacy of 5 dose levels of oral rapamycin for prolonging renal allograft survival in pigs. Untreated and triple therapy groups (cyclosporine, azathioprine, and prednisone) served as controls. Immunosuppression was administered for 28 days posttransplant and then stopped. Rapamycin whole-blood concentrations were followed weekly. Chemistry, hematology, and lipid values were monitored post-transplant. For rapamycin-treated pigs, median survival time (MST) correlated with both dose and trough levels (ng/ml). All kidneys had some degree of rejection seen on necropsy. After rejection, pneumonia was the most common cause of death. No specific end-organ toxicity was noted on histopathologic examination. Triglyceride and cholesterol levels increased in all treated pigs (both rapamycin and triple therapy) vs. untreated controls--however, all values were within normal limits. Mean ALT levels increased in weeks 2 to 4 in the higher-dose rapamycin groups but returned to baseline in pigs surviving after the drug was stopped. ALT levels did not increase above twice normal in any group. Creatinine levels correlated with the degree of rejection seen on biopsy. We noted no other toxicities. We conclude that rapamycin, given as oral monotherapy, is an effective and safe immunosuppressant in our large animal renal allograft model. Outcome correlated with dose and whole-blood levels.

Physician-induced demand for surgery.

Following up the earlier findings by Fuchs on surgeon-induced demand, this paper makes numerous data and econometric improvements in conducting a test of neoclassical and inducement theories. A simultaneous equation model is used to estimate physician demand and equilibrium fees for surgery from a sample of 350 PSUs over the 1969-76 period. The results provide definite support for the notion of competitive market failure--particularly in large metropolitan areas. Other things equal, fees and utilization are higher in surgeon-rich areas although our estimated shift elasticities were only about one-third those found by Fuchs. A statistically significant, albeit small price elasticity of demand for surgery was also obtained, in contrast to Fuchs. Increasing monopoly and disequilibrium models are also tested without altering the basic findings. Where surgeons were in short supply, their availability significantly affected surgery rates, although a small supply effect was found in plentiful areas as well.

Physician behavior under the Medicare assignment option.

Using a national sample of general practitioners, internists, and general surgeons, we analyzed the willingness of physicians to accept Medicare patients on assignment. Assignment rates were found to be very sensitive to reimbursement and administrative practices under Medicare. A ten percent increase in the prevailing charge, for example, raised assignment by 14.7 percent. The assigned and non-assigned components of the Medicare program were found to compete with each other; assignment rates were lower where the demand for non-assigned services was stronger. As for the kinds of physicians who take assignment, they were disproportionately general surgeons and foreign medical graduates.

Relative incomes and rates of return for U.S. physicians.

Since 1967 the supply of physicians in the U.S. has been growing by more than 3 percent per annum. This, coupled with public insurer fee discounts, might have been expected to depress both the relative and absolute incomes of physicians in spite of growing insurance coverage and new technologies. Real incomes of physicians did decline at a 0.2 percent annual rate between 1967 and 1980, but this was apparently due to economy-wide events since the income trends for lawyers, dentists, and college graduates were virtually identical. Internal rates of return to undergraduate medical training remained high--between 14 and 17 percent in 1980. Specialty training became more profitable for internists, general surgeons, and obstetricians/gynecologists (all with 10-15 percent rates of return), while pediatricians continued to suffer a financial loss. While Medicare and Medicaid fee discounts have been criticized as inequitable, the programs are also shown to provide a 'hidden subsidy' to physicians during residency training, materially adding to rates of returns.

An analysis of the Prospective Payment System's labor-nonlabor share by diagnosis-related group.

When Congress in 1983 legislated a new Prospective Payment System (PPS) for Medicare hospital payment, the payment algorithm was founded on a simplifying assumption of a constant 80-20 percentage share of labor and nonlabor costs across all diagnosis-related groups (DRGs). Using Medicare claims data and hospital cost reports, this study examines the accuracy of this assumption. While a few DRGs are found to vary significantly from the norm, a systematic cancelling out of high and low labor-intensive DRGs results in no material PPS payment bias at the hospital level. Indeed, rural hospitals, if anything, benefit by the assumption. A very small number of outlier DRGs and hospitals are troublesome, nonetheless, implying fine-tuning of the algorithm.

Are rural referral centers as costly as urban hospitals?

This article evaluates the claim that rural referral centers (RRCs), identified by HCFA criteria for special treatment under Medicare's prospective payment system, have average costs similar to urban hospitals. Multivariate analysis led us to conclude that RRC Medicare costs were 13 percent higher than those of other rural hospitals in 1984, holding constant Medicare case mix, teaching activity, and relative wages. However, RRCs were 9 percent ($200) less costly per case than urban hospitals. Outliers explained most of the cost difference between RRCs and urban hospitals, while transfers were more important in explaining differences between RRCs and other rural hospitals. Given that bed size alone explained all of the RRC-other rural cost difference, paying RRCs the urban rate results in an indirect way of paying them based on bed size. It also gives them an average excess of payment over Medicare cost well above the national rural and urban average.

Impact of Medicare payment reductions on access to surgical services.

OBJECTIVE: This study evaluates the impact of surgical fee reductions under Medicare on the utilization of surgical services. DATA SOURCES: Medicare physician claims data were obtained from 11 states for a five-year time period (1985-1989). STUDY DESIGN: Under OBRA-87, Medicare reduced payments for 11 surgical procedures. A fixed effects regression method was used to determine the impact of these payment reductions on access to care for potentially vulnerable Medicare beneficiaries: joint Medicaid-eligibles, blacks, and the very old. DATA COLLECTION/EXTRACTION METHODS: Medicare claims and enrollment data were used to construct a cross-section time-series of population-based surgical rates from 1985 through 1989. PRINCIPAL FINDINGS: Reductions in surgical fees led to small but significant increases in use for three procedures, small decreases in use for two procedures, and no impact on the remaining six procedures. There was little evidence that access to surgery was impaired for potentially vulnerable enrollees; in fact, declining fees often led to greater rates of increases for some subgroups. CONCLUSIONS: Our results suggest that volume responses by surgeons to payment changes under the Medicare Fee Schedule may be smaller than HCFA's original estimates. Nevertheless, both access and quality of care should continue to be closely monitored.

Measuring differences and similarities in hospital caseloads: a conceptual and empirical analysis.

OBJECTIVE: This article conceptually and empirically evaluates alternative index measures that have been used to distinguish among hospital caseloads. It introduces two new measures. DATA SOURCES/STUDY SETTING: The study relies on 1987 Medpar data, which provide a 100 percent sample of Medicare Part A claims for the calendar year. STUDY DESIGN: Descriptive statistics indicate the sensitivity of alternative caseload measures to hospital bed size, region, and urban/rural location. Multiple regression analysis then examines the ability of the caseload measures to distinguish among hospitals based on hospital- and area-specific characteristics. DATA COLLECTION/EXTRACTION METHODS: A provider level file containing the number of cases treated by each provider in each DRG was constructed from the Medpar data and merged with data from the American Hospital Association and the Area Resource File. PRINCIPAL FINDINGS: Different indexes purporting to measure hospital specialization are often evaluating very different aspects of the hospitals' caseloads. Prior work has indicated a specialization among hospitals during the period from 1980 to 1985. Replication of this work using other indexes could verify the increase in specialization and might provide a clearer picture of market or hospital characteristics associated with changing caseloads.

An economic model of large Medicaid practices.

Public attention given to Medicaid "mills" prompted this more general investigation of the origins of large Medicaid practices. A dual market demand model is proposed showing how Medicaid competes with private insurers for scarce physician time. Various program parameters--fee schedules, coverage, collection costs--are analyzed along with physician preferences, specialties, and other supply-side characteristics. Maximum likelihood techniques are used to test the model. The principal finding is that in raising Medicaid fees, as many physicians opt into the program as expand their Medicaid caseloads to exceptional levels, leaving the maldistribution of patients unaffected while notably improving access. Still, the fact that Medicaid fees are lower than those of private insurers does lead to reduced access to more qualified practitioners. Where anti-Medicaid sentiment is stronger, access is also reduced and large Medicaid practices more likely to flourish.

The changing nature of physicians' office visits.

Although there is a general feeling that, into the early 1980s, overall improvement was occurring in the content and quality of physicians' services, no time-series documentation to date has appeared to support this assumption. This article provides empirical evidence that physicians' office visits were in fact changing over time, though not in ways that one might expect. Rather than involving more diagnostic services, such as laboratory tests and x-rays, the typical office visit had come to include more therapeutic services, especially counseling. This is consistent with the observed increase in time spent with patients: between 1974 and 1981, the average office visit increased in length by nearly one full minute. Multivariate analysis indicates that the typical office visit was changing largely because physicians themselves were changing. Not only were physicians becoming increasingly specialized, but they were also more likely to be female, in group practice, and board-certified.

The oblique effect in orientation acuity.

We have examined the dependence of rotational acuity on the orientation bandwidth of a stimulus using two-dimensional, band-pass filtered, spatial noise. Stimuli had a bandwidth of 0.5 octave of spatial frequency, centred at 5.0 cyc/deg, and an orientation bandwidth that covered the range from 0.0 to 25.0 deg. Thresholds were obtained on one principal (vertical), and one oblique axis (45 deg). It was found that acuity declined on both axes as bandwidth increased, in a manner that was compatible with simple statistical principles with virtually perfect sampling of the image. There was some evidence that the intrinsic noise is greater on the oblique axis than on the vertical, and that oblique axes are less densely sampled than the principal axes. These differences are small and are insufficient, either on their own or taken together to explain the oblique effect.

Impact of State hospital rate setting on capital formation.

For this article, a new national data base of Medicare's cost reports on more than 2,000 hospitals is used to measure the impact of State prospective rate setting on capital formation. Several investment measures are analyzed, both in nominal and real terms, using a combination of descriptive and multivariate techniques. Results indicate that, over the last decade, State hospital rate-setting programs have had little demonstrable effect on capital formation and they have not caused any significant aging of plant assets. Programs in both New York and Massachusetts were found to be associated with a slowing in the rate of bed growth, however, resulting in significant long-term cost savings.

Does one national prospective payment system market basket make sense?

For the first 4 years of Medicare's prospective payment system (PPS), one national market basket of cost weights and price proxies has been used to update payment rates. Previous evidence for a single rate is reviewed, and more recent data are presented that show definite regional differences in input price inflation, resulting in systematic gains or losses for some regions. However, as long as the Health Care Financing Administration continues to periodically update its hospital wage index, the net impact on hospitals is minor. Nevertheless, large differences in PPS-excluded hospital cost shares indicate the need for two sets of cost weights.

Hospital department cost and employment increases: 1980-92.

Hospital costs have continued to rise at rates well in excess of inflation generally, even after the introduction of Medicare's per case prospective payment system (PPS). This article uses a hospital subscriber microcost reporting system to show trends in costs, wages, labor hours, and outputs for more than 50 individual departments from 1980-92. Descriptive results show dramatic growth in the operating room, catheter lab, and other technologically driven cost centers. Administrative costs also increased rapidly through 1988, but slowed thereafter. The paperwork billing and collection burden of hospitals is estimated to be $6 billion in 1992, or approximately 4 percent of total expenses.