Instrumental variables technique: cigarette price provided better estimate of effects of smoking on SF-12

OBJECTIVE

Debate surrounds the usefulness of the instrumental variables (IV) technique for medical research. The choice of an instrument for the technique has been contentious. This study estimated the effects of smoking on physical functional status. We chose an especially valid and strong instrument: cigarette price.

STUDY DESIGN AND SETTING

The data were a nationally representative cross-sectional sample of 34,288 persons aged 30 to 91 in 1996-1997. The sample was drawn from the Community Tracking Study. Number of cigarettes smoked per day was predicted by the average cigarette price for the state in which the subject resided. The outcome measure was physical functional status and was measured by the SF-12 physical functional index.

RESULTS

In multivariable models we found the following: cigarettes per day was strongly and negatively associated with the SF-12 index (P<.001); cigarette price was strongly and negatively associated with cigarettes per day (P=.002); the predicted cigarettes per day (the IV) was strongly and negatively associated with the SF-12 index in linear regression and tobit regression (P=.047 and P=.021).

CONCLUSION

Estimated coefficients from the IV method suggested that the effect of smoking on physical functional status was substantially larger than estimates that relied on conventional methods.

Neurologists' assessment of their ability to provide high quality care

OBJECTIVE

S: To assess levels of professional satisfaction and distress in a national sample of neurologists and to compare neurologists with other physicians.

METHODS

The authors used data from the 1996 through 1997 and 1998 through 1999 Community Tracking Study Physician Survey and analyzed responses in the two time frames to measures of career satisfaction, physician autonomy and communication, and ability to obtain needed services for patients.

RESULTS

Most physicians, including neurologists, are satisfied with careers in medicine. Neurologists feel they have more time to spend with patients than do other physicians but are more concerned than are other physicians about their ability to obtain needed services and to provide high-quality care for patients. One-third of all physicians feel that they cannot maintain the kind of continuing relationships with patients over time that are necessary for delivering high-quality care.

CONCLUSION

The majority of physicians, including neurologists, are satisfied with medical practice today. Because some neurologists are experiencing significant professional distress, those factors that will enhance physician satisfaction, prevent burnout, and encourage high-quality interpersonal care need to be carefully examined and modified.

Tracking career satisfaction and perceptions of quality among US obstetricians and gynecologists

OBJECTIVE

To assess recent trends in professional satisfaction, perceptions of ability to provide high-quality care, and perceptions of ability to obtain needed services for patients in a national sample of obstetricians and gynecologists; to compare obstetrician-gynecologists with physicians in other specialties; and to identify demographic, professional, and practice characteristics associated with high career satisfaction.

METHODS

We used data from the 1996-1997 (n=12,385; response rate, 65%) and 1998-1999 (n=12,280; response rate, 61%) waves of the nationally representative Community Tracking Study physicians' survey. The principal outcome measures were one item related to overall career satisfaction, six items measuring physicians' perceptions of their ability to provide high-quality care, and five items measuring physicians' perceptions of their ability to obtain needed services for patients. All results were weighted and adjusted to reflect the complex survey design.

RESULTS

In 1996-1997, 34% of obstetrician-gynecologists (n=545) were very satisfied with their careers, and 24% were very or somewhat dissatisfied. Up to 45% perceived significant barriers to the delivery of high-quality care, and up to 58% were unable to "almost or almost always" obtain necessary services for patients. Results in 1998-1999 (n=484 obstetricians and gynecologists) were similar, except for a deterioration in perceived amount of time with patients and ability to obtain high-quality ancillary services. In comparison with primary care physicians, obstetrician-gynecologists were less satisfied (P=.001); in comparison with both primary care physicians and general surgeons, they had more problems delivering high-quality care (P<.001) and greater difficulties obtaining needed services for patients (P<.001). Controlling for selected demographic and professional characteristics, higher career satisfaction was associated with age greater than 65 years, practicing in small metropolitan areas and in academic settings, and having better perceptions of quality and ability to obtain services (P<.05).

CONCLUSION

Although most obstetricians and gynecologists are satisfied with their careers, many are experiencing significant professional distress.

Vaginal birth after cesarean in California

OBJECTIVE

To estimate rates at which women were offered and consented to trial of labor in California hospitals with high and low risk-adjusted cesarean delivery rates.

METHODS

From 267 nonfederal acute-care hospitals in California that performed more than 678 deliveries in 1992-1993, 51 hospitals were selected in a stratified sample. Hospitals in the sample were categorized as having high, medium, and low risk-adjusted cesarean rates using a logistic regression model based on data from the California Patient Discharge Data System. We reviewed medical records of women with previous cesareans for evidence of counseling regarding trial of labor, other clinical variables, and method of delivery. Differences in proportions between the three groups of hospitals were compared.

RESULTS

According to records of 369 women with previous cesareans, after excluding contraindications, 312 were potentially eligible for trial of labor. Hospitals with low risk-adjusted cesarean rates documented counseling women for trial of labor in over 99% of records reviewed, compared with 85% and 79%, respectively, of hospitals with intermediate and high rates (P <.001). Rates of completed vaginal births after cesarean were 71% in hospitals with low risk-adjusted cesarean rates, compared with 39% and 31% in hospitals with intermediate and high rates (P <.05).

CONCLUSIONS

California hospitals with high cesarean rates in 1992-1993 had markedly higher rates of repeat elective cesarean delivery without evidence of counseling regarding trial of labor. Informed patient choice is a critical element of the decision for trial of labor or elective repeat cesarean, and lack of documented counseling is cause for concern.

The origin and fate of herniated lumbar intervertebral disc tissue

STUDY DESIGN

In a clinicopathologic study, disc tissue collected from surgery and from cadaveric spines was examined to test an hypothesis about the pathogenesis of herniation.

OBJECTIVES

To determine the origin and fate of herniated lumbar intervertebral disc tissue.

SUMMARY OF BACKGROUND DATA

Previous studies have ascribed herniated disc tissue to the nucleus, anulus, or endplate, or combinations of the three. One study describes it as newly synthesized fibrocartilage. Regardless of its origin, peripheral neovascularization of disc fragments has been described and may be related to pain symptoms.

METHODS

Disc tissue was collected after extrusion and was examined histologically to determine its origin and fate. To test the hypothesis that sequestration results from migration of isolated, degenerate fragments of nucleus pulposus through preexisting tears in the anulus fibrosus, cadaveric lumbar disc were examined in detail.

RESULTS

Ninety-eight percent of sequestrations contained some nuclear material indicating that nucleus pulposus is the principal substance extruded from the disc. None contained anulus alone. Although vascular repair was present in 89% of specimens, it did not correlate with several clinical parameters.

CONCLUSIONS

The autopsy study confirmed the model of nuclear fragmentation, migration, and extrusion along radiating anular clefts. Neovascularization of extruded fragments bore no relationship with duration of sciatic pain symptoms or clinical outcome.

Type 1 fimbrial expression enhances Escherichia coli virulence for the urinary tract

Type 1 fimbriae are adhesion organelles expressed by many Gram-negative bacteria. They facilitate adherence to mucosal surfaces and inflammatory cells in vitro, but their contribution to virulence has not been defined. This study presents evidence that type 1 fimbriae increase the virulence of Escherichia coli for the urinary tract by promoting bacterial persistence and enhancing the inflammatory response to infection. In a clinical study, we observed that disease severity was greater in children infected with E. coli O1:K1:H7 isolates expressing type 1 fimbriae than in those infected with type 1 negative isolates of the same serotype. The E. coli O1:K1:H7 isolates had the same electrophoretic type, were hemolysin-negative, expressed P fimbriae, and carried the fim DNA sequences. When tested in a mouse urinary tract infection model, the type 1-positive E. coli O1:K1:H7 isolates survived in higher numbers, and induced a greater neutrophil influx into the urine, than O1:K1:H7 type 1-negative isolates. To confirm a role of type 1 fimbriae, a fimH null mutant (CN1016) was constructed from an O1:K1:H7 type 1-positive parent. E. coli CN1016 had reduced survival and inflammatogenicity in the mouse urinary tract infection model. E. coli CN1016 reconstituted with type 1 fimbriae (E. coli CN1018) had restored virulence similar to that of the wild-type parent strain. These results show that type 1 fimbriae in the genetic background of a uropathogenic strain contribute to the pathogenesis of E. coli in the urinary tract.

High prevalence of Helicobacter pylori antibodies in an institutionalized population: evidence for person-to-person transmission

OBJECTIVE

To evaluate the prevalence of H. pylori antibodies in mentally and physically handicapped adults living together in a long-term care facility.

METHODS

One hundred twenty-two institutionalized subjects from six living areas were compared to a normal representative Caucasian population obtained by random sampling from the urban population area of Melbourne. Serum samples from 1977 and 1989 from 122 subjects were tested for H. pylori antibody by an ELISA technique. The data were analyzed by Student's t test, chi 2 test and logistic regression.

RESULTS

Ninety-two of the 122 subjects (75%) from whom sera was collected in 1989 were seropositive for H. pylori, compared with only 23% in age- and sex-matched control subjects (p < 0.0001). The prevalence of H. pylori antibodies in 1977 was 34% (42/122). Of the remaining 80 seronegative subjects, 51 (61.4%) converted to became positive in the 12-yr interval. The annual seroconversion rate was 7.4%, with an average of 4.25 newly positive subjects each year. The prevalence of H. pylori in 1989 was significantly higher than in 1977 after adjustment for age (odds ratio 2.39, 95% CI 1.1-5.3, p = 0.03).

CONCLUSIONS

H. pylori antibodies are significantly more prevalent in institutionalized adults compared with controls from the general population. These data support the hypothesis that H. pylori is acquired by either fecal-oral or oral-oral transmission.

Ribotyping of Helicobacter pylori from clinical specimens

Ribotyping is a method used to type strains of bacteria by analyzing the restriction enzyme digestion patterns of the rRNA genes. This method was applied to 126 strains of Helicobacter pylori from 100 unrelated symptomatic patients who had endoscopies done and to 15 strains from 15 infected subjects from seven families. Analysis of the rRNA gene patterns revealed 77 distinct ribotypes from the 100 patients. From 15 of these subjects, isolates were recovered from antral mucosal biopsies at follow-up endoscopy. All follow-up isolates from the same patient, with one exception, yielded identical digest patterns. This patient had strains with two distinct digest patterns obtained from a set of three isolates cultured from biopsy specimens taken at different times. Five patients who had isolates recovered from different sites in the stomach (antrum, gastric body, duodenum, and pyloric channel) showed ribotyping patterns which were identical for each patient yet distinct between patients. In seven family groups studied, identical digest patterns were detected in members of two families, with variability in strains detected among members of the remaining families. This study demonstrates that ribotyping provides a useful, reliable, reproducible, and highly discriminatory typing scheme for the study of H. pylori infection.

A comparison of diagnostic tests to determine Helicobacter pylori infection

Twenty-five Helicobacter pylori positive and 25 H. pylori negative subjects as defined by culture and phase contrast microscopy of antral biopsy specimens obtained from routine upper endoscopy were studied. Antral biopsies were examined by rapid urease test, phase contrast microscopy, culture and histology. Venous blood was tested for H. pylori specific IgG antibodies by an ELISA technique. Within 7 days of endoscopy the patients also had a [14C]-urea breath test. The sensitivity and specificity of the rapid urease test was 92%, the breath test 96% and 100%, histopathology 96% and 91% and serology 96% and 88%, respectively. The [14C]-urea breath test performed over 1 h with sampling of subjects at 0, 0.5 and 1 h was an accurate and reliable method. Results expressed as counts per minute of the expired 14CO2 proved to be a simple method of assessing H. pylori status. A significant correlation between severity of histological antral gastritis and the amount of 14CO2 expired was observed. This study has shown that the non-invasive 14C-urea breath test and serology are highly sensitive and specific for the diagnosis of H. pylori infection.