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Biomedical subjects

David Johnson

Publications and source records attributed to David Johnson.

At least 37 records · Page 2Linked to original sources
PubMed2005

Association between physician specialty and volumes of treated patients and mortality among patients hospitalized for newly diagnosed heart failure.

PURPOSE: To assess the effects of hospital care by a specialist or nonspecialist physician, and by volume of treated patients, on mortality among hospitalized patients with newly diagnosed heart failure. METHODS: Data describing heart failure patients in Alberta, Canada, from April 1, 1994, to March 31, 2000, were extracted from hospital abstracts and analyzed using hierarchical regression, with adjustment for patient demographic characteristics, comorbid conditions, physician volume, physician specialty, and hospital volume. RESULTS: There were 16,162 hospital discharges for heart failure. Nonspecialist physicians were predominantly in the two lowest-volume quartiles (93%) and specialists were predominantly in the two highest-volume quartiles (68%). Considering the effects of volume alone and after adjustment for comorbidity, for each 10 additional hospital patients treated by a physician, the odds ratio for in-hospital mortality was 0.97 (95% confidence interval [CI]: 0.95 to 0.98), and the odds ratio for 1-year mortality was 0.99 (95% CI: 0.98 to 0.999). In analyses that considered both volume and specialty, the odds of in-hospital mortality decreased by 4% for each 10 additional in-hospital patients treated by a physician (odds ratio [OR] = 0.96; 95% CI: 0.95 to 0.98). In these same analyses, the odds ratio for in-hospital mortality was 1.32 (95% CI: 1.13 to 1.53) for general practitioners with specialist consultation and 1.32 (95% CI: 1.08 to 1.61) for specialists compared with general practitioners without specialist consultations. At 1 year, mortality was not associated significantly with the volume of in-hospital patients treated, or with the specialty of the treating physician. CONCLUSION: Treatment by high-volume physicians during hospitalization for newly diagnosed heart failure was associated with a decrease in mortality, but these benefits did not persist at 1 year. The increased mortality noted in patients treated by specialists may be due to residual confounding or unmeasured comorbidity.

Adult↗
PubMed2005

Compliance with post-operative adjuvant chemotherapy in non-small cell lung cancer. An analysis of National Cancer Institute of Canada and intergroup trial JBR.10 and a review of the literature.

Resected non-small cell lung cancer (NSCLC) has 5-years survival rates of 30-70%. The role of adjuvant chemotherapy remains unclear with poor compliance reported in most trials. The compliance with adjuvant chemotherapy (ACT) for stage IB and II NSCLC was analyzed using data from a North American multi-centre phase III study (accrual 1994-2001) that compared adjuvant chemotherapy to observation. Planned chemotherapy consisted of cisplatin (CIS) 50 mg/m2 days 1, 8 and vinorelbine (VIN) 25 mg/m2 days 1, 8, 15, 22 for four cycles; the VIN dose had been reduced from 30 mg/m2 after an initial cohort of patients experienced unacceptable toxicity. Four hundred and twenty-four patients were randomized after the amendment, 215 to the chemotherapy arm. Median age was 60 years, 64% were male and 84% had stage II disease. Thirty-seven patients completed one cycle, 14 completed two, 20 completed three and 108 patients completed all four cycles. Ten patients received no therapy. Multivariate analysis demonstrated statistically significant differences in compliance with extent of surgery, gender and age. Patients randomized in Canada were more likely to fail to complete chemotherapy due to refusal of therapy than their American counterparts. Patients who had pneumonectomies were more likely to discontinue therapy due to toxicity than those who had lesser resections. Extent of surgery may play a role in both the compliance and toxicity of ACT. Differences between nations in the perception of the risks and benefits of adjuvant chemotherapy regimens, both between physicians and patients, should be investigated further.

Adult↗
PubMed2005

The utility of administrative data in helping the clinician understand and treat community-acquired pneumonia.

We illustrate the benefits and limitations of administrative data when trying to understand diseases such as CAP. Administrative data provide an understanding of care provided or risk factors in unselected patients under actual practice conditions. Administrative data can supplement understandings gained from randomized trials in a timely and cost-efficient manner using data previously collected. As the use of administrative data increases, the type of data collected will change to reflect these new uses. Administrative data use may represent a practical solution in monitoring quality of care for entire populations.

Adolescent↗
PubMed2005

Low salivary cortisol levels and externalizing behavior problems in youth.

Research linking basal cortisol levels with internalizing and externalizing behavior problems in youths has yielded inconsistent results. We hypothesize that the high moment to moment variation in adrenocortical activity requires an analytical strategy that separates variance in cortisol levels attributable to "stable traitlike" versus "state or situationally specific" sources. Early morning saliva samples were obtained from 724 youths (M age = 13.5 years; range = 6-16 years in Year 1) on 2 successive days 1 year apart. Latent state-trait modeling revealed that 70% of the variance in cortisol levels could be attributed to statelike sources, and 28% to traitlike sources. For boys only, higher levels of externalizing problem behaviors were consistently associated with lower cortisol attributable to traitlike sources across 3 years of behavioral assessment. The inverse association between individual differences in cortisol and externalizing problem behavior has previously only been reported in studies of at-risk or clinical groups. The present findings suggest the relationship is a stable phenomenon that spans both normative and atypical child development. Studies are needed to reveal the biosocial mechanisms involved in the establishment and maintenance of this phenomenon, and to decipher whether individual differences in this hormone-behavior link confers risk or resilience.

Adolescent↗
PubMed2005

Cross-sectional and longitudinal association between antihypertensive medications and cognitive impairment in an elderly population.

BACKGROUND: The effect of antihypertensive medications on cognitive function has not been well studied. The authors' objectives were to investigate the cross-sectional and longitudinal association between the use of antihypertensive medications and cognitive function and to compare different antihypertensive medication classes with regard to this association in an elderly population. METHODS: The medical records of a convenience sample of patients (n = 993 cross-sectional and 350 longitudinal; mean age, 76.8 +/- 0.3 years; 74% women; 87% White) followed at a geriatric practice were reviewed. Data abstracted included demographics, medical history (Alzheimer's disease [AD] or vascular dementia [VaD]), use of antihypertensive medications, and results of cognitive assessments (the Mini-Mental Status Examination [MMSE] and the Clock Draw Test [CDT]). RESULTS: In the cross-sectional analysis, antihypertensive use was not associated with MMSE (p >.05), CDT (p >.05), or dementia diagnosis (odds ratio for AD, 0.8; 95% confidence interval [CI], 0.6 to 1.2; odds ratio for VaD, 1.6; 95% CI, 0.6 to 4.0). In the longitudinal analysis, antihypertensive use was associated with a lower rate of cognitive decline on the MMSE (-0.8 +/- 2 points in users vs -5.8 +/- 2.5 points in nonusers; p =.007) and on the CDT (-0.3 +/- 0.8 points in users vs -2.2 +/- 0.8 points in nonusers; p =.002), and with a lower risk for the development of cognitive impairment (odds ratio, 0.56; 95% CI, 0.38 to 0.83; p =.004). The trend was similar in patients with baseline AD (p =.02). Patients taking diuretics (p =.007), angiotensin-converting enzyme inhibitors (p =.016), and beta-blockers (p =.014) had a lower rate of cognitive decline, and patients taking angiotensin receptor blockers (p =.016) had improved cognitive scores. CONCLUSIONS: Antihypertensive use, particularly diuretics, angiotensin-converting enzymes inhibitors, beta-blockers, and angiotensin receptor blockers, may be associated with a lower rate of cognitive decline in older adults, including those with AD. Until a randomized clinical trial confirms our results, findings of this observational study should be interpreted with caution.

Adult↗
PubMed2005

Altered messenger RNA and protein expressions for insulin-like growth factor family members in clear cell and papillary renal cell carcinomas.

BACKGROUND: The purpose of the present paper was to describe the pattern of expression of insulin-like growth factor (IGF-I) and its regulatory binding proteins (IGFBP) in renal cell carcinoma (RCC). METHODS: The expressions of mRNA and protein for various IGF members were assessed in 24 paired normal and malignant human renal tissues (16 clear cell and 8 papillary RCC) using semiquantitative reverse transcription-polymerase chain reaction and immunohistochemistry. Paired tissue samples were also obtained from six patients with oncocytoma in order to compare the specificity of changes in IGF/IGFBP expression between tumors derived from proximal (RCC) and distal (oncocytoma) tubular epithelium. RESULTS: Clear cell RCC were characterized by significant increases in the mRNA expression of IGF-I, IGFBP-3 and IGFBP-6 while papillary RCC exhibited down-regulated expression of IGF-I, IGFBP-4 and IGFBP-5. The IGFBP-2, IGFBP-4 and IGFBP-5 mRNA were down-regulated in oncocytomas. Semiquantitative assessment of immunohistochemical staining demonstrated significant increases in epithelial associated IGF-I and IGFBP-3 in clear cell RCC, increased IGFBP-5 protein in papillary RCC and no significant changes in IGF/IGFBP protein expression in oncocytoma. CONCLUSIONS: The expression of IGF-I and certain IGFBP is significantly altered in RCC compared with normal renal tissue and oncocytomas. This altered expression is differentially regulated according to the histologic subtype of RCC, and suggests that the IGF/IGFBP axis may play an important role in determining the malignant phenotype of RCC.

Adenocarcinoma, Clear Cell↗
PubMed2005

Prospective multicenter study of eligibility for antiviral therapy among 4,084 U.S. veterans with chronic hepatitis C virus infection.

BACKGROUND: Many veterans may not be candidates for hepatitis C virus (HCV) treatment due to contraindications to therapy. The aims of this study were to determine the proportion of HCV-infected veterans who were eligible for interferon alfa and ribavirin therapy and to evaluate barriers to HCV treatment. METHODS: We prospectively enrolled 4,084 veterans who were referred for HCV treatment over a 1-yr period at 24 Veterans Affairs (VA) Medical Centers. Treatment candidacy was assessed using standardized criteria and the opinion of the treating clinician. RESULTS: Overall, 32.2% (95% CI, 30.8-33.7%) were candidates for HCV treatment according to standardized criteria, whereas 40.7% (95% CI, 39.2-42.3%) were candidates in the opinion of the treating clinician. Multivariable analysis identified ongoing substance abuse (OR = 17.68; 95% CI, 12.24-25.53), comorbid medical disease (OR = 9.62; 95% CI, 6.85-13.50), psychiatric disease (OR = 9.45; 95% CI, 6.70-13.32), and advanced liver disease (OR = 8.43; 95% CI, 4.42-16.06) as the strongest predictors of not being a treatment candidate. Among patients who were considered treatment candidates, 76.2% (95% CI, 74.0-78.3%) agreed to be treated and multivariable analysis showed that persons >/=50 yr of age (OR = 1.37; 95% CI, 1.07-1.76) and those with >50 lifetime sexual partners (OR = 1.44; 95% CI, 1.08-1.93) were more likely to decline treatment. CONCLUSIONS: The majority of veteran patients are not suitable candidates for HCV treatment because of substance abuse, psychiatric disease, and comorbid medical disease, and many who are candidates decline therapy. Multidisciplinary collaboration is needed to overcome barriers to HCV therapy in this population.

Antiviral Agents↗
PubMed2005

Assessing the risk of laboratory-acquired meningococcal disease.

Neisseria meningitidis is infrequently reported as a laboratory-acquired infection. Prompted by two cases in the United States in 2000, we assessed this risk among laboratorians. We identified cases of meningococcal disease that were possibly acquired or suspected of being acquired in a laboratory by placing an information request on e-mail discussion groups of infectious disease, microbiology, and infection control professional organizations. A probable case of laboratory-acquired meningococcal disease was defined as illness meeting the case definition for meningococcal disease in a laboratorian who had occupational exposure to an N. meningitidis isolate of the same serogroup within 14 days of illness onset. Sixteen cases of probable laboratory-acquired meningococcal disease occurring worldwide between 1985 and 2001 were identified, including six U.S. cases between 1996 and 2000. Nine cases (56%) were serogroup B; seven (44%) were serogroup C. Eight cases (50%) were fatal. All cases occurred among clinical microbiologists. In 15 cases (94%), isolate manipulation was performed without respiratory protection. We estimated that an average of three microbiologists are exposed to the 3,000 meningococcal isolates seen in U.S. laboratories yearly and calculated an attack rate of 13/100,000 microbiologists between 1996 and 2001, compared to 0.2/100,000 among U.S. adults in general. The rate and case/fatality ratio of meningococcal disease among microbiologists are higher than those in the general U.S. population. Specific risk factors for laboratory-acquired infection are likely associated with exposure to droplets or aerosols containing N. meningitidis. Prevention should focus on the implementation of class II biological safety cabinets or additional respiratory protection during manipulation of suspected meningococcal isolates.

Adult↗
PubMed2005

Initial evaluation of the effects of aerosolized Florida red tide toxins (brevetoxins) in persons with asthma.

Florida red tides annually occur in the Gulf of Mexico, resulting from blooms of the marine dinoflagellate Karenia brevis. K. brevis produces highly potent natural polyether toxins, known as brevetoxins, that activate voltage-sensitive sodium channels. In experimental animals, brevetoxins cause significant bronchoconstriction. A study of persons who visited the beach recreationally found a significant increase in self-reported respiratory symptoms after exposure to aerosolized Florida red tides. Anecdotal reports indicate that persons with underlying respiratory diseases may be particularly susceptible to adverse health effects from these aerosolized toxins. Fifty-nine persons with physician-diagnosed asthma were evaluated for 1 hr before and after going to the beach on days with and without Florida red tide. Study participants were evaluated with a brief symptom questionnaire, nose and throat swabs, and spirometry approved by the National Institute for Occupational Safety and Health. Environmental monitoring, water and air sampling (i.e., K. brevis, brevetoxins, and particulate size distribution), and personal monitoring (for toxins) were performed. Brevetoxin concentrations were measured by liquid chromatography mass spectrometry, high-performance liquid chromatography, and a newly developed brevetoxin enzyme-linked immunosorbent assay. Participants were significantly more likely to report respiratory symptoms after Florida red tide exposure. Participants demonstrated small but statistically significant decreases in forced expiratory volume in 1 sec, forced expiratory flow between 25 and 75%, and peak expiratory flow after exposure, particularly those regularly using asthma medications. Similar evaluation during nonexposure periods did not significantly differ. This is the first study to show objectively measurable adverse health effects from exposure to aerosolized Florida red tide toxins in persons with asthma. Future studies will examine the possible chronic effects of these toxins among persons with asthma and other chronic respiratory impairment.

Adolescent↗
PubMed2005

Occupational exposure to aerosolized brevetoxins during Florida red tide events: effects on a healthy worker population.

Karenia brevis (formerly Gymnodinium breve) is a marine dinoflagellate responsible for red tides that form in the Gulf of Mexico. K. brevis produces brevetoxins, the potent toxins that cause neurotoxic shellfish poisoning. There is also limited information describing human health effects from environmental exposures to brevetoxins. Our objective was to examine the impact of inhaling aerosolized brevetoxins during red tide events on self-reported symptoms and pulmonary function. We recruited a group of 28 healthy lifeguards who are occupationally exposed to red tide toxins during their daily work-related activities. They performed spirometry tests and reported symptoms before and after their 8-hr shifts during a time when there was no red tide (unexposed period) and again when there was a red tide (exposed period). We also examined how mild exercise affected the reported symptoms and spirometry tests during unexposed and exposed periods with a subgroup of the same lifeguards. Environmental sampling (K. brevis cell concentrations in seawater and brevetoxin concentrations in seawater and air) was used to confirm unexposed/exposed status. Compared with unexposed periods, the group of lifeguards reported more upper respiratory symptoms during the exposed periods. We did not observe any impact of exposure to aerosolized brevetoxins, with or without mild exercise, on pulmonary function.

Adolescent↗
PubMed2005

A multidisciplinary community hospital program for early and rapid resuscitation of shock in nontrauma patients.

OBJECTIVE: To determine the effect of a community hospital-wide program enabling nurses and prehospital personnel to mobilize institutional resources for the treatment of patients with nontraumatic shock. DESIGN: Historically controlled single-center study. SETTING: A 180-bed community hospital. PATIENTS: Patients in shock who were candidates for aggressive therapy. INTERVENTIONS: From January 1998 to May 31, 2000, patients in shock received standard therapy (control group). During the month of June 2000, intensive education of all health-care providers (ie, prehospital personnel, nurses, and physicians) took place. From July 1, 2000, through June 30, 2001, patients in shock (protocol group) were managed with a hospital-wide shock program. The program included early recognition of shock and the initiation of therapy by nonphysicians. Frontline personnel mobilized a shock team, which used goal-directed resuscitation protocols, early intensivist involvement, and rapid transfer to the ICU where protocols specific to shock etiology were implemented. MEASUREMENTS AND MAIN RESULTS: Eighty-six and 103 patients, respectively, were enrolled in the control and protocol groups. Baseline characteristics were similar. The protocol group had significant reductions in the median times to interventions, as follows: intensivist arrival, 2:00 h to 50 min (p < 0.002); ICU/operating room admission, 2 h 47 min to 1 h 30 min (p < 0.002); 2 L fluid infused, 3 h 52 min to 1 h 45 min (p < 0.0001); and pulmonary artery catheter placement, 3 h 50 min to 2 h 10 min (p 0.02). Good outcomes (ie, discharged to home or to a rehabilitation center) were more likely in the protocol group than in the control group (p = 0.02). The hospital mortality rate was 40.7% in the control group and 28.2% in the protocol group (p = 0.035). CONCLUSION: Similar to current practice in patients who have experienced trauma or cardiac arrest, the empowerment of nonphysician providers to mobilize hospital resources for the care of patients with shock is effective. A community hospital program incorporating the education of providers, the activation of a coordinated team response, and early goal-directed therapy expedited appropriate treatment and was temporally associated with improved outcomes. Randomized multicenter trials are needed to further assess the impact of the shock program on outcomes.

Aged↗
PubMed2005

Late neurologic and cognitive sequelae of inflicted traumatic brain injury in infancy.

OBJECTIVE: There is limited information regarding the long-term outcome of inflicted traumatic brain injury (TBI), including shaken infant syndrome. The purpose of this study was to describe the long-term neurologic, behavioral, and cognitive sequelae seen in this population. METHODS: A cross-sectional and prospective longitudinal study was conducted of 25 children with inflicted TBI in Scotland between 1980 and 1999. After consent was obtained, neurologic and cognitive examinations were performed on all participants and sequentially in the prospective cohort. Two global outcome measures were used: Glasgow Outcome Score (GOS) and Seshia's outcome score. Cognitive outcome was assessed using the Bayley Scales of Infant Development, British Ability Scales, and the Vineland Adaptive Behavior Scales. RESULTS: The mean length of follow-up was 59 months. A total of 68% of survivors were abnormal on follow-up, 36% had severe difficulties and were totally dependant, 16% had moderate difficulties, and 16% had mild difficulties on follow-up. A wide range of neurologic sequelae were seen, including motor deficits (60%), visual deficits (48%), epilepsy (20%), speech and language abnormalities (64%), and behavioral problems (52%). There was a wide range of cognitive abilities: the mean psychomotor index, 69.9 (SD: +/-25.73); and mean mental development index, 74.53 (SD: +/-28.55). Adaptive functioning showed a wide range of difficulties across all domains: communication domain (mean: 76.1; SD: +/-25.4), Daily living skills domain (mean: 76.9; SD: +/-24.3), and socialization domain (mean: 79.1; SD: +/-23.1). Outcome was found to correlate with the Pediatric Trauma Score and the Glasgow Coma Score but did not correlate with age at injury or mechanism of injury. CONCLUSIONS: Inflicted TBI has a very poor prognosis and correlates with severity of injury. Extended follow-up is necessary so as not to underestimate problems such as specific learning difficulties and attentional and memory problems that may become apparent only once the child is in school. Behavioral problems are present in 52% and begin to manifest clinically between the second and third years of life, although the consequences of frontal lobe injury may be underestimated unless follow-up is extended into adolescence and early adulthood.

Adolescent↗
PubMed2005

Automated reporting of GFR--coming soon to a laboratory near you!

BACKGROUND: Serum creatinine concentration is an unreliable and insensitive marker of chronic kidney disease (CKD). To improve CKD detection, Australasian guidelines have recently recommended that laboratories calculate and report an estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease (MDRD) formula with every request for serum creatinine concentration. OBJECTIVE: This articles aims to provide timely information to health professionals about how to appropriately interpret and act upon eGFR reports. It also discusses the treatments shown to reduce renal and cardiovascular risk in CKD patients, and the indications for nephrologist referral. DISCUSSION: The accuracy and precision of eGFRs are reasonable in most adults in whom calculated values are ENTITY lt 60 mL/min/1.73 m2. However, eGFRs should be interpreted with caution in some settings (particularly patients with eGFRs ENTITY gt 60 mL/min/1.73 m2 and children). Automatic laboratory reporting of eGFR will enhance early detection of CKD, allow the timely institution of appropriate reno- and cardio-protective therapies, and better inform decisions regarding the prescription of renally excreted medications.

Adult↗
PubMed2005

Assessing the effectiveness of food worker training in Florida: opportunities and challenges.

The task of measuring the effectiveness of food worker training has historically met with many challenges. This paper considers various approaches and utilizes trends in foodborne-outbreak contributing factors to evaluate a recent change in Florida's food worker training. Results show that subsequent to training, the relative incidence of many factors that contribute to foodborne outbreaks actuay increased, while the relative incidence of other factors decreased. The overall rate of foodborne outbreaks associated with the contributing factors that the authors studied decreased subsequent to training. Results of this analysis must be interpreted with caution because of multiple confounding factors; however, it became apparent that both increases and decreases in the occurrence of contributing factors could be used to focus future training material on areas of food handler practices in which it is needed. Further work needs to be done to estabish the most useful methods and approaches for assessing effectiveness and hence the public health impact of food worker training.

Disease Outbreaks↗
PubMed2005

Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: a position statement.

The systematic staging of chronic kidney disease (CKD) by glomerular filtration measurement and proteinuria has allowed the development of rational and appropriate management plans. One of the barriers to early detection of CKD is the lack of a precise, reliable and consistent measure of kidney function. The most common measure of kidney function is currently serum creatinine concentration. It varies with age, sex, muscle mass and diet, and interlaboratory variation between measurements is as high as 20%. The reference interval for serum creatinine concentration includes up to 25% of people (particularly thin, elderly women) who have an estimated glomerular filtration rate (eGFR) that is significantly reduced (< 60 mL/min/1.73 m). The recent publication of a validated formula (MDRD) to estimate GFR from age, sex, race and serum creatinine concentration, without any requirement for measures of body mass, allows pathology laboratories to "automatically" generate eGFR from data already acquired. Automatic laboratory reporting of eGFR calculated from serum creatinine measurements would help to identify asymptomatic kidney dysfunction at an earlier stage. eGFR correlates well with complications of CKD and an increased risk of adverse outcomes such as cardiovascular morbidity and mortality. We recommend that pathology laboratories automatically report eGFR each time a serum creatinine test is ordered in adults. As the accuracy of eGFR is suboptimal in patients with normal or near-normal renal function, we recommend that calculated eGFRs above 60 mL/min/1.73 m be reported by laboratories as "> 60 mL/min/1.73 m", rather than as a precise figure.

Journal Article↗
PubMed2005

Croup.

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Bronchodilator Agents↗