Quantitative Detection of Cathepsin B Activity in Neutral pH Buffers Using Gold Microelectrode Arrays: Toward Direct Multiplex Analyses of Extracellular Proteases in Human Serum

Proteases are critical signaling molecules and prognostic biomarkers for many diseases including cancer. There is a strong demand for multiplex bioanalytical techniques that can rapidly detect the activity of extracellular proteases with high sensitivity and specificity. This study demonstrates an activity-based electrochemical biosensor of a 3 × 3 gold microelectrode array for the detection of cathepsin B activity in human serum diluted in a neutral buffer. Proteolysis of ferrocene-labeled peptide substrates functionalized on 200 × 200 μm microelectrodes is measured simultaneously over the nine channels by AC voltammetry. The protease activity is represented by the inverse of the exponential decay time constant (1/τ), which equals to (k_cat/K_M)[CB] based on the Michaelis-Menten model. An enhanced activity of the recombinant human cathepsin B (rhCB) is observed in a low-ionic-strength phosphate buffer at pH = 7.4, giving a very low limit of detection of 8.49 × 10^-4 s^-1 for activity and 57.1 pM for the active rhCB concentration that is comparable to affinity-based enzyme-linked immunosorbent assay (ELISA). The cathepsin B presented in the human serum sample is validated by ELISA, which mainly detects the inactive proenzyme, while the electrochemical biosensor specifically measures the active cathepsin B and shows significantly higher decay rates when rhCB and human serum are activated. Analyses of the kinetic electrochemical measurements with spiked active cathepsin B in human serum provide further assessment of the protease activity in the complex sample. This study lays the foundation to develop the gold microelectrode array into a multiplex biosensor for rapid detection of the activity of extracellular proteases toward cancer diagnosis and treatment assessment.

Electrochemical Activity Assay for Protease Analysis Using Carbon Nanofiber Nanoelectrode Arrays

There is a strong demand for bioanalytical techniques to rapidly detect protease activities with high sensitivity and high specificity. This study reports an activity-based electrochemical method toward this goal. Nanoelectrode arrays (NEAs) fabricated with embedded vertically aligned carbon nanofibers (VACNFs) are functionalized with specific peptide substrates containing a ferrocene (Fc) tag. The kinetic proteolysis curves are measured with continuously repeated ac voltammetry, from which the catalytic activity is derived as the inverse of the exponential decay time constant based on a heterogeneous Michaelis-Menten model. Comparison of three peptide substrates with different lengths reveals that the hexapeptide H2N-(CH2)4-CO-Pro-Leu-Arg-Phe-Gly-Ala-NH-CH2-Fc is the optimal probe for cathepsin B. The activity strongly depends on temperature and is the highest around the body temperature. With the optimized peptide substrate and measuring conditions, the limit of detection of cathepsin B activity and concentration can reach 2.49 × 10-4 s-1 and 0.32 nM, respectively. The peptide substrates show high specificity to the cognate proteases, with negligible cross-reactions among three cancer-related proteases cathepsin B, ADAM10, and ADAM17. This electrochemical method can be developed into multiplex chips for rapid profiling of protease activities in cancer diagnosis and treatment monitoring.

A consensus exercise identifying priorities for research into clinical effectiveness among children's orthopaedic surgeons in the United Kingdom

Aims

High-quality clinical research in children's orthopaedic surgery has lagged behind other surgical subspecialties. This study used a consensus-based approach to identify research priorities for clinical trials in children's orthopaedics.

Methods

A modified Delphi technique was used, which involved an initial scoping survey, a two-round Delphi process and an expert panel formed of members of the British Society of Children's Orthopaedic Surgery. The survey was conducted amongst orthopaedic surgeons treating children in the United Kingdom and Ireland.

Results

A total of 86 clinicians contributed to both rounds of the Delphi process, scoring priorities from one (low priority) to five (high priority). Elective topics were ranked higher than those relating to trauma, with the top ten elective research questions scoring higher than the top question for trauma. Ten elective, and five trauma research priorities were identified, with the three highest ranked questions relating to the treatment of slipped capital femoral epiphysis (mean score 4.6/ 5), Perthes' disease (4.5) and bone infection (4.5).

Conclusion

This consensus-based research agenda will guide surgeons, academics and funders to improve the evidence in children's orthopaedic surgery and encourage the development of multicentre clinical trials. Cite this article: Bone Joint J 2018;100-B:680-4.

Specialist integrated haematological malignancy diagnostic services: an Activity Based Cost (ABC) analysis of a networked laboratory service model

AIMS

Specialist Integrated Haematological Malignancy Diagnostic Services (SIHMDS) were introduced as a standard of care within the UK National Health Service to reduce diagnostic error and improve clinical outcomes. Two broad models of service delivery have become established: 'co-located' services operating from a single-site and 'networked' services, with geographically separated laboratories linked by common management and information systems. Detailed systematic cost analysis has never been published on any established SIHMDS model.

METHODS

We used Activity Based Costing (ABC) to construct a cost model for our regional 'networked' SIHMDS covering a two-million population based on activity in 2011.

RESULTS

Overall estimated annual running costs were £1 056 260 per annum (£733 400 excluding consultant costs), with individual running costs for diagnosis, staging, disease monitoring and end of treatment assessment components of £723 138, £55 302, £184 152 and £94 134 per annum, respectively. The cost distribution by department was 28.5% for haematology, 29.5% for histopathology and 42% for genetics laboratories. Costs of the diagnostic pathways varied considerably; pathways for myelodysplastic syndromes and lymphoma were the most expensive and the pathways for essential thrombocythaemia and polycythaemia vera being the least.

CONCLUSIONS

ABC analysis enables estimation of running costs of a SIHMDS model comprised of 'networked' laboratories. Similar cost analyses for other SIHMDS models covering varying populations are warranted to optimise quality and cost-effectiveness in delivery of modern haemato-oncology diagnostic services in the UK as well as internationally.

An unusual cause of acute obstructive jaundice in an HIV-infected patient

We describe the case of an HIV-1-infected patient presenting with acute obstructive jaundice as the initial manifestation of primary small bowel Burkitt's lymphoma. The biliary obstruction resolved rapidly following chemotherapy without the need for surgical intervention. The prognosis is favourable with appropriate timely treatment.

Antenatal perspective of hypoplastic left heart syndrome: 5 years on

BACKGROUND

Palliative staged reconstructive surgery has radically altered the outcome of babies with hypoplastic left heart syndrome (HLHS).

AIM

To compare the current outcome of antenatally diagnosed HLHS with a series 5 years previously now that paediatric cardiothoracic and postnatal paediatric intensive care techniques have been further refined.

METHOD

Comparison of all cases of HLHS diagnosed antenatally at Birmingham Women's Hospital between 1 January 2000 and 31 December 2004 with results of the previous series.

RESULTS

79 fetuses were identified with HLHS. The median gestational age at diagnosis was 22 weeks. After counselling, 20 (25.3%) couples terminated the pregnancy compared with 43.7% in the previous cohort (p = 0.01). Of the 59 couples who continued with the pregnancy, four had stillbirths and two were lost to follow-up. Subsequently, there were 53 live births, of which six babies had an alternative major congenital heart disease diagnosed postnatally; 10 babies were not considered for surgery (parents' wishes) and died after compassionate care; 31 babies underwent surgery. The early (30 days) surgical mortality after stage 1 Norwood procedure was 19.4% and 20 patients are still alive. In the cohort of intention-to-treat cases, the overall survival was 46.9% (23/49).

CONCLUSION

The number of parents choosing termination after an antenatal diagnosis of HLHS has almost halved since 5 years ago. Despite the significant increase in surgical survival following stage 1 Norwood in this period, in the intention-to-treat cohort the survival was 46.9%. These data again highlight the poorer outcome for babies with congenital malformations diagnosed in utero in comparison with those identified postnatally.

Economic disparity in bicycle helmet use by children six years after the introduction of legislation

BACKGROUND

Studies evaluating the effectiveness of bicycle helmet legislation often focus on short term outcomes. The long term effect of helmet legislation on bicycle helmet use is unknown.

OBJECTIVE

To examine bicycle helmet use by children six years after the introduction of the law, and the influence of area level family income on helmet use.

METHODS

The East York (Toronto) health district (population 107,822) was divided into income areas (designated as low, mid, and high) based on census tract data from Statistics Canada. Child cyclists were observed at 111 preselected sites (schools, parks, residential streets, and major intersections) from April to October in the years 1995-1997, 1999, and 2001. The frequency of helmet use was determined by year, income area, location, and sex. Stratified analysis was used to quantify the relation between income area and helmet use, after controlling for sex and bicycling location.

RESULTS

Bicycle helmet use in the study population increased from a pre-legislation level of 45% in 1995 to 68% in 1997, then decreased to 46% by 2001. Helmet use increased in all three income areas from 1995 to 1997, and remained above pre-legislation rates in high income areas (85% in 2001). In 2001, six years post-legislation, the proportion of helmeted cyclists in mid and low income areas had returned to pre-legislation levels (50% and 33%, respectively). After adjusting for sex and location, children riding in high income areas were significantly more likely to ride helmeted than children in low income areas across all years (relative risk = 3.4 (95% confidence interval, 2.7 to 4.3)).

CONCLUSION

Over the long term, the effectiveness of bicycle helmet legislation varies by income area. Alternative, concurrent, or ongoing strategies may be necessary to sustain bicycle helmet use among children in mid and low income areas following legislation.

How can the principles of complexity science be applied to improve the coordination of care for complex pediatric patients?

Clinical and technological advances in medicine have resulted in more patients requiring multidisciplinary care and coordination of services. This is particularly challenging in pediatrics, given the dependency of children. Coordination of care is a key ingredient of quality care; when suboptimal, clinical outcomes and satisfaction can suffer. In this article we view coordination of care through the lens of complexity science in an effort to find new solutions to this healthcare challenge.

Staged surgical management of hypoplastic left heart syndrome: a single institution 12 year experience

OBJECTIVE

To describe a 12 year experience with staged surgical management of the hypoplastic left heart syndrome (HLHS) and to identify the factors that influenced outcome.

METHODS

Between December 1992 and June 2004, 333 patients with HLHS underwent a Norwood procedure (median age 4 days, range 0-217 days). Subsequently 203 patients underwent a bidirectional Glenn procedure (stage II) and 81 patients underwent a modified Fontan procedure (stage III). Follow up was complete (median interval 3.7 years, range 32 days to 11.3 years).

RESULTS

Early mortality after the Norwood procedure was 29% (n = 95); this decreased from 46% (first year) to 16% (last year; p < 0.05). Between stages, 49 patients died, 27 before stage II and 22 between stages II and III. There were one early and three late deaths after stage III. Actuarial survival (SEM) was 58% (3%) at one year and 50% (3%) at five and 10 years. On multivariable analysis, five factors influenced early mortality after the Norwood procedure (p < 0.05). Pulmonary blood flow supplied by a right ventricle to pulmonary artery (RV-PA) conduit, arch reconstruction with pulmonary homograft patch, and increased operative weight improved early mortality. Increased periods of cardiopulmonary bypass and deep hypothermic circulatory arrest increased early mortality. Similar factors also influenced actuarial survival after the Norwood procedure.

CONCLUSION

This study identified an improvement in outcome after staged surgical management of HLHS, which was primarily attributable to changes in surgical technique. The RV-PA conduit, in particular, was associated with a notable and independent improvement in early and actuarial survival.

Rasch analysis of the Western Ontario McMaster (WOMAC) Osteoarthritis Index: results from community and arthroplasty samples

BACKGROUND AND OBJECTIVE

This study is based on secondary analysis of Western Ontario McMaster Osteoarthritis Index (WOMAC) data from a community sample over 55 years and total hip or knee arthroplasty samples presurgery and 1-year postoperative.

METHODS

The WOMAC data were evaluated by Rasch analysis. Data were considered to fit the Rasch mathematical model for the pain and physical dimensions of the WOMAC if unidimensionality was confirmed by principle component analysis of the subscale and the residuals from the Rasch analysis, infit and outfit statistics were in the range of 0.80 to 1.20; if there was no differential item functioning based on gender or hip vs. knee subjects; and, if there was stability of the item logits across the three data samples.

RESULTS

A three-item pain dimension (excluding night pain and pain on standing) and a 14-item physical dimension (excluding heavy domestic duties, getting in and out of the bath and getting on and off the toilet) fit the Rasch model based on these criteria.

CONCLUSION

In evaluating existing health status questionnaires using Rasch methodology, it is important to evaluate relevant patient samples and longitudinal data when the measure is intended to evaluate change in status. By these criteria, a modified WOMAC questionnaire fits the Rasch model and has interval-level scaling properties.

Population pharmacokinetics of adjuvant cyclophosphamide, methotrexate and 5-fluorouracil (CMF)

Despite the success of adjuvant cyclophosphamide, methotrexate (MTX), 5-fluouracil (5-FU) (CMF) treatment for early stage breast cancer, more than 35% of patients die within 5 years of diagnosis. Optimisation of the dose of each component drug may improve survival and reduce toxicity. In this study, the pharmacokinetics of intravenous (i.v.) cyclophosphamide (600 mg/m(2)), MTX (40 mg/m(2)) and 5-FU (600 mg/m(2)) were determined in 46 women, with data on two consecutive courses available for 41 patients. A population analysis using NONMEM was performed to investigate the effect of patient covariates on pharmacokinetics (PK), and to estimate the relative magnitude of interindividual and interoccasion variability. Patient weight had a significant influence on the clearance of cyclophosphamide and on the volume of central compartment for MTX, whose clearance was dependent on renal function. For all three drugs, interoccasion variability was of the same order (20-40%) as that between individuals, suggesting a limited potential for dose-optimisation of this regimen.

A taxonomy for responsiveness

Responsiveness is quickly becoming a critical criterion for the selection of outcomes measures in studies of treatment effectiveness, economic appraisals, and other program evaluations. Statistical characteristics, specifically "large effect sizes," are often felt to indicate the relative worth of one instrument over another. However, debates about their meaning led the present authors to propose a taxonomy for responsiveness based on the context of the study concerned. The three axes underlying the classification system relate to: who is this being analyzed for (individuals or groups); which scores are being contrasted (over time/at one point in time); and the type of change being quantified (for example, observed change or important change). It is concluded that responsiveness should be considered a highly contextualized attribute of an instrument, rather than a static property and should be described only in that way. A questionnaire could thus be described as being "responsive to" a given category in the new taxonomy.

An evaluation of the quality of clinical trials in anesthesia

BACKGROUND

The authors evaluated the quality of clinical trials published in four anesthesia journals during the 20-yr period from 1981-2000.

METHODS

Trials published in four major anesthesia journals during the periods 1981-1985, 1991-1995, and the first 6 months of 2000 were grouped according to journal and year. Using random number tables, four trials were selected from all of the eligible clinical trials in each journal in each year for the periods 1981-1985 and 1991-1995, and five trials were selected from all of the trials in each journal in the first 6 months of 2000. Methods and results sections from the 160 trials from 1981-1985 and 1991-1995 were randomly ordered and distributed to three of the authors for blinded review of the quality of the study design according to 10 predetermined criteria (weighted equally, maximum score of 10): informed consent and ethics approval, eligibility criteria, sample size calculation, random allocation, method of randomization, blind assessment of outcome, adverse outcomes, statistical analysis, type I error, and type II error. After these trials were evaluated, 20 trials from the first 6 months of 2000 were randomly ordered, distributed, and evaluated as described.

RESULTS

The mean (+/- SD) analysis scores pooled for the four journals increased from 5.5 +/- 1.4 in 1981-1985 to 7.0 +/- 1.1 in 1991-1995 (P < 0.00001) and to 7.8 +/- 1.5 in 2000. For 7 of the 10 criteria, the percentage of trials from the four journals that fulfilled the criteria increased significantly between 1981-1985 and 1991-1995. During the 20-yr period, the reporting of sample size calculation and method of randomization increased threefold to fourfold, whereas the frequency of type I statistical errors remained unchanged.

CONCLUSION

Although the quality of clinical trials in four major anesthesia journals has increased steadily during the past two decades, specific areas of trial methodology require further attention.

Measuring the whole or the parts? Validity, reliability, and responsiveness of the Disabilities of the Arm, Shoulder and Hand outcome measure in different regions of the upper extremity

The Disabilities of the Arm, Shoulder and Hand (DASH) outcome measure was developed to evaluate disability and symptoms in single or multiple disorders of the upper limb at one point or at many points in time.

PURPOSE

The purpose of this study was to evaluate the reliability, validity, and responsiveness of the DASH in a group of diverse patients and to compare the results with those obtained with joint-specific measures.

METHODS

Two hundred patients with either wrist/hand or shoulder problems were evaluated by use of questionnaires before treatment, and 172 (86%) were re-evaluated 12 weeks after treatment. Eighty-six patients also completed a test-retest questionnaire three to five days after the initial (baseline) evaluation. The questionnaire package included the DASH, the Brigham (carpal tunnel) questionnaire, the SPADI (Shoulder Pain and Disability Index), and other markers of pain and function. Correlations or t-tests between the DASH and the other measures were used to assess construct validity. Test-retest reliability was assessed using the intraclass correlation coefficient and other summary statistics. Responsiveness was described using standardized response means, receiver operating characteristics curves, and correlations between change in DASH score and change in scores of other measures. Standard response means were used to compare DASH responsiveness with that of the Brigham questionnaire and the SPADI in each region.

RESULTS

The DASH was found to correlate with other measures (r > 0.69) and to discriminate well, for example, between patients who were working and those who were not (p<0.0001). Test-retest reliability (ICC = 0.96) exceeded guidelines. The responsiveness of the DASH (to self-rated or expected change) was comparable with or better than that of the joint-specific measures in the whole group and in each region.

CONCLUSIONS

Evidence was provided of the validity, test-retest reliability, and responsiveness of the DASH. This study also demonstrated that the DASH had validity and responsiveness in both proximal and distal disorders, confirming its usefulness across the whole extremity.

Hip function in patients >55 years old: population reference values

The purpose of this study was to establish population values for hip function for patients of different ages using the validated WOMAC scoring system and the traditional Harris hip scoring system. A random sample of 184 individuals who had no prior history of hip or knee pain or pathology was evaluated. The average WOMAC scores for pain, function, and stiffness were 0.01, 1.8, and 0.4. The average Harris hip score was 94 +/- 8.2. No significant correlation was noted between the summary WOMAC score, the WOMAC stiffness or pain subscales, or the overall Harris hip score for any of the 3 age groups studied. Patients with complaints in other joints, such as the back and neck, had lower WOMAC and Harris hip scores. Adults who are healthy and do not have a prior history of hip or knee pathology do not show a significant decline in hip function as they grow older. A deterioration in the function of a total hip arthroplasty over time cannot be attributed solely to the aging process.

Repair of truncus arteriosus: a considered approach to right ventricular outflow tract reconstruction

OBJECTIVE

In repair of truncus arteriosus the accepted methods of establishing right ventricle (RV) to pulmonary artery (PA) continuity utilize an allograft or xenograft valved conduit. Alternatively, the PA confluence may be directly anastomosed to the RV with anterior patch augmentation, which may allow growth and delay or avoid subsequent RVOT obstruction. These methods of RVOT reconstruction were evaluated in infants undergoing truncus arteriosus repair.

METHODS

A retrospective analysis of 61 infants undergoing repair of truncus arteriosus between November 1988 and June 2000 was performed. Median age was 34 days (range 1 day to 6.4 months). The patient cohort was subdivided into two groups (1) Valved conduit group: RV to PA continuity performed with a conduit in 38 patients using allograft (28) or xenograft (10). (2) Direct anastomosis group: direct RV-PA anastomosis performed in 23 patients, augmented anteriorly with monocusp (15) or simple pericardial patch (eight).

RESULTS

There were eight hospital deaths (13%, 95% confidence limits 5--21%). Hospital mortality did not differ significantly between group 1 and 2 (three patients (8%) versus five patients (22%) respectively, P=0.23). By multivariate analysis, low operative weight (P=0.023), severe truncal regurgitation (P=0.022) and major coronary abnormalities (P=0.018), were independent risk factors for hospital death. Hospital survivors were followed-up from 1.3 months to 11.8 years (mean 4.2+/-3.4 years). There were eight late deaths with survival of 73+/-6% at 2 years and beyond. Survival was not influenced by method of RVOT reconstruction (Conduit versus direct RV-PA anastomosis, 2.76+/-7%, 63+/-10%, respectively, P=0.23). Freedom from surgical RVOT reintervention was 56+/-10% in group 1 and 89+/-10% in group 2 at 10 years (P=0.023). The use of a xenograft conduit was an independent risk factor for reintervention (P<0.001).

CONCLUSIONS

In truncus arteriosus repair, RV to PA continuity established by a direct anastomosis was associated with a low incidence of surgical RVOT re-intervention. This technique has the potential for RVOT growth and may be a useful alternative when an appropriate allograft is unavailable, particularly in the neonate where the risk of pulmonary hypertension are lower.

Comparison of three outcomes instruments in children

SUMMARY

The purpose of this study was to compare prospectively the distributions, validity, and discriminative ability of three pediatric outcome questionnaires. Consecutive patients completed the Activities Scales for Kids (ASK), the Child Health Questionnaire Parent Form (CHQ-PF-28), and the Pediatrics Outcomes Data Collection Instrument (PODCI). The scores of the three instruments were compared with each other and with parents' and clinicians' ratings. Of 210 patients, 166 (79%) completed the three questionnaires. The CHQ-PF-28 had a different distribution than the other two questionnaires and showed both floor and ceiling effects. The ASK and PODCI instruments were highly correlated and discriminated better than the CHQ-PF-28, with fewer floor and ceiling effects. Each questionnaire, however, seemed to be measuring slightly different things.

Pharmacological study of paclitaxel duration of infusion combined with GFR-based carboplatin in the treatment of ovarian cancer

PURPOSE

To determine the effect on systemic pharmacology and clinical toxicity of dose and mode of administration of paclitaxel combined with carboplatin in the treatment of ovarian cancer.

PATIENTS AND METHODS

A total of 18 patients were treated with a dose of carboplatin determined by GFR, to attain a target AUC of 6 or 7 mg/ml x min. The paclitaxel dose was 175 or 200 mg/m2 administered over approximately 1 or 3 h. The duration of infusion was randomized, crossing over to the alternative treatment for the second course. Blood samples were analysed for carboplatin, paclitaxel and for the excipients of the paclitaxel formulation, ethanol and Cremophor.

RESULTS

Overall the three-weekly schedule of administration of the combination of carboplatin and paclitaxel was well tolerated. There were no clinical differences in the toxicities observed between courses where a 1-h infusion was used compared with those with a 3-h infusion. The target AUC of carboplatin was achieved (mean +/- SD 114 +/- 20% of target). Analysis of paclitaxel pharmacokinetics did not show a difference in the AUC or time above a pharmacological threshold for the two infusion durations. The peak concentration of paclitaxel obtained at the end of the infusion (9.1 vs 4.5 microg/ml), and the plasma ethanol concentration (40.0 vs 20.5 mg/dl) were higher following the shorter duration infusion. Peak concentrations of Cremophor were not different.

CONCLUSION

The combination of paclitaxel at a dose of 175 mg/m2 and carboplatin at a target AUC of 6-7 mg/ml min can safely be administered every 3 weeks. Also, a 1-h infusion of paclitaxel has no acute clinical disadvantage over a 3-h infusion and these durations of administration are pharmacologically equivalent.

A comparison of patients' responses about their disability with and without attribution to their affected area

The purpose of this study was to determine whether individual items in a disability questionnaire were answered differently depending on whether or not the questions were attributed to the upper limb (i.e., "do you have difficulty eating due to your arm or hand problem?" or "do you have difficulty eating?", respectively). The a priori hypothesis was that the same or more disability would be detected by nonattributed items. Four hundred sixty-seven patients with upper extremity disorders completed the SF-36 general health survey, which does not attribute health problems to affected areas. Patients also completed six additional questions, modified from the SF-36, regarding work (four questions) and social function with friends and family (two questions), which attributed their disability to their affected upper extremity. Of 467 patients, 419-431 (89-92%) responded to both versions of the questions. Although we demonstrated a significant order effect (Generalized Estimating Equation; P=.003), comparison of the responses to the six questions showed that for five of the six questions (Generalized Estimating Equation; P< or = .001) patients reported more disability when the questions were worded with attribution to the upper extremity. Even considering the order effect, patients demonstrated a counterintuitive result by reporting more disability when questions were attributed to their affected area. Thus, both the wording of questions and order of questions can significantly affect patients' responses about their disability and raises questions about the validity of patients' reports of their disability.

"Are you better?" A qualitative study of the meaning of recovery

PURPOSE

Research into the meaning of illness has often focused on an individual's transition into a state of being ill, for example the adoption of a sick role. The question "Are you better?" addresses the transition out of this state and is fundamental to the patient-clinician relationship, guiding decisions about treatment. However, the question assumes that all patients have the same meaning for "being better." The purpose of this study was to explore the meaning of the concept of recovery (getting better) in a group of people with upper limb musculoskeletal disorders.

METHODS

Qualitative (grounded theory) methods were used. Individual interviews were conducted with 24 workers with work-related musculoskeletal disorders of the upper limb. The audiotaped interviews were transcribed and coded for content. Categories were linked, comparisons made, and a theory built about how people respond to the question "Are you better?"

RESULTS

The perception of "being better" is highly contextualized in the experience of the individual. Being better is not only reflected in changes in the state of the disorder (resolution) but could be an adjustment of life to work around the disorder (readjustment) or an adaptation to living with the disorder (redefinition). The experience of the disorder can be influenced by factors such as the perceived legitimacy of the disorder, the comparators used to define health and illness, and coping styles, which in turn can influence being better.

CONCLUSION

Two patients could mean very different things when saying that they are better. Some may not actually have a change in disease state as measured by symptoms, impairments, or function.

Short stature as a screening test for endocrinopathy in slipped capital femoral epiphysis

Slipped capital femoral epiphysis may be associated with hypothyroidism and other endocrinopathies. Routine screening for such abnormalities is unlikely to be cost-effective since the overall incidence of these disorders, in association with slipped capital femoral epiphysis, is low. The identification of a presenting characteristic which would predict the chance of an associated endocrinopathy would allow only selected children to be screened. Our aim was to determine if certain characteristics were useful as a screen for patients with an underlying endocrinopathy who presented with slipped capital femoral epiphysis. Between January 1988 and December 1996 we recorded gender, age, height, unilateral or bilateral involvement and an associated diagnosis of endocrinopathy for all patients who were treated for slipped capital femoral epiphysis. Of 166 such patients 13 (7.8%) had an endocrinopathy. Height was the only useful screening characteristic, although bilateral involvement was more likely in those with an endocrinopathy. Most (90.9%) of this latter group were below the tenth percentile for height compared with only 5.4% in those who did not have an endocrinopathy (p < 0.005). The sensitivity and negative predictive value of detecting an underlying endocrinopathy in a patient presenting with a slipped capital femoral epiphysis and short stature (tenth percentile or less) were 90.2% and 98.6%, respectively. Patients who are on or below the tenth percentile for height at the time of presentation should be screened for a possible endocrine abnormality using measurement of thyroid-stimulating hormone and free thyroxine as a preliminary screening test. These hormones are most likely to be abnormal in the presence of endocrine dysfunction.

Changing rates of cancer. The hazards of using a single definition

Changing cancer rates, abstracted from tumor registries, are used to make inferences about the effect of carcinogens and cancer treatments on a population-wide basis. We compared the annual age-standardized incidence rates of extremity soft tissue sarcomas from two large tumor registries using different case definitions. We identified all limb soft tissue sarcoma cases diagnosed 1973-1993 in the Ontario Cancer Registry (OCR) and the Surveillance, Epidemiology, and End Results (SEER) databases. Two case definitions for limb soft tissue sarcoma were used based on missing data, incomplete diagnostic methods and ICD-9 codes; an upper limit estimate of the rates which included all possible cases of limb soft tissue sarcoma and a lower limit estimate of the rates which included all definite cases of limb soft tissue sarcoma (with the true rates lying in between). The upper limit OCR rates showed a statistically significant decreasing linear trend (slope = -0.021, P < 0.01). Whereas the slope of the OCR lower limit regression line showed a statistically significant increase in rates (slope = 0.01, P = 0.04). Neither the upper or lower limit SEER rates had a statistically significant linear trend (slope = 0.002, P = 0.60 and slope = 0.001, P = 0.18, respectively). Case definition affects incidence rates and changing rates of cancer. Thus the use of a single case definition along with changing coding practices may alone explain changing cancer rates.

Determining the need for hip and knee arthroplasty: the role of clinical severity and patients' preferences

BACKGROUND

Area variation in the use of surgical interventions such as arthroplasty is viewed as concerning and inappropriate.

OBJECTIVES

To determine whether area arthroplasty rates reflect patient-related demand factors, we estimated the need for and the willingness to undergo arthroplasty in a high- and a low-use area of Ontario, Canada.

RESEARCH DESIGN

Population-based mail and telephone survey.

SUBJECTS

All adults aged > or =55 years in a high (n = 21,925) and low (n = 26,293) arthroplasty use area.

MEASURES

We determined arthritis severity and comorbidity with questionnaires, established the presence of arthritis with examination and radiographs, and evaluated willingness to have arthroplasty with interviews. Potential arthroplasty need was defined as severe arthritis, no absolute contraindication for surgery, and evidence of arthritis on examination and radiographs. Estimates of need were then adjusted for patients' willingness to undergo arthroplasty.

RESULTS

Response rates were 72.0% for questionnaires and interviews. The potential need for arthroplasty was 36.3/1,000 respondents in the high-rate area compared with 28.5/1,000 in the low-rate area (P <0.0001). Among individuals with potential need, only 14.9% in the high-rate area and 8.5% in the low-rate area were definitely willing to undergo arthroplasty (P = 0.03), yielding adjusted estimates of need of 5.4/1,000 and 2.4/1,000 in the high- and low-rate areas, respectively.

CONCLUSIONS

Demonstrable need and willingness were greater in the high-rate area, suggesting these factors explain in part the observed geographic rate variations for this procedure. Among those with severe arthritis, no more than 15% were definitely willing to undergo arthroplasty, emphasizing the importance of considering both patients' preferences and surgical indications when evaluating need and appropriateness of rates for surgery.

Early results of right ventricular-pulmonary artery conduits in patients under 1 year of age

OBJECTIVES

Management strategies for the repair of many complex heart defects require the implantation of a valved conduit between the right ventricle (RV) and the pulmonary artery (PA), often using aortic or pulmonary homograft valves. Their limited availability, however, has led to the development and use of new conduits. We retrospectively compared our experience with small homografts in patients of less than 1 year of age with the TissueMed bioprosthetic valved conduit.

METHODS

From March 1994 to November 1997 29 patients in their first year of life underwent conduit implantation for complex heart defects. These were retrospectively reviewed in order to determine the incidence of death or conduit stenosis. Seventeen patients received homografts and 12 TissueMed conduits.

RESULTS

Diagnoses and operative details including conduit size were similar in the two groups and in all cases complete repair of the underlying defect was carried out. Early post-operative mortality was 4/17 (23.5%) in the homograft group and 3/12 (25%) in the TissueMed group. Echo Doppler evaluation within 1 month of operation showed no right ventricular outflow tract (RVOT) obstruction in any of the survivors. In the TissueMed group 8/9 (77%) survivors have gone on to develop significant RVOT obstruction within 12 months of operation. There have been three late deaths in this group all related to severe RVOT obstruction. Two patients died during an attempt at balloon dilatation and one patient died of progressive right heart failure. Five patients had successful replacement of the TissueMed conduit. One child remains well with no evidence of RVOT obstruction. At operation to replace conduit, or at autopsy, the stenoses were related to the deposition of fibrous tissue at the anastomotic suture lines. In the homograft group none of the survivors developed RVOT obstruction during the first 12 months post-operatively. There was one late death (non-cardiac in origin) and one child is awaiting conduit replacement 40 months after initial implantation for obstruction.

CONCLUSIONS

The homograft is a satisfactory conduit for re-establishment of RV-PA continuity in infancy. Further work needs to be undertaken in order to elucidate the mechanisms of early graft failure in bioprosthetic conduits if these are to be a suitable alternative for RV outflow reconstruction in infants.

Looking for important change/differences in studies of responsiveness. OMERACT MCID Working Group. Outcome Measures in Rheumatology. Minimal Clinically Important Difference

The purpose of this paper is to describe a classification system for studies of responsiveness that was designed to help organize these studies, and identify those with the potential to provide information on minimal clinically important difference (MCID). We developed a 3 dimensional cube into which studies of responsiveness can be categorized based on their evaluation of 3 attributes: 1. individual or group setting; 2. which scores are contrasted; and 3. the type of change or difference being assessed. We present and discuss examples of studies that fit into categories in the classification cube. This classification system helps to focus attention on whether the literature is able to provide information on the specific type of change a person is interested in. It reinforces that the ability of an instrument to detect a certain category of discrimination within the cube does not mean it will necessarily be responsive to another category. The cube has been shown here as a means to separate out studies that address important change. These studies can then be examined as the source of information on MCID.

Estimation of glomerular filtration rate in cancer patients

The frequent need to obtain an estimate of renal function in cancer patients, not least for targeting carboplatin dose, has led to a number of approaches to estimate glomerular filtration rate (GFR). This study aimed to develop a simple and reliable method to estimate GFR using readily-available patient characteristics. Data from 62 patients with estimates of 51Cr-EDTA clearance were analysed to determine the most appropriate formula relating this method of measuring GFR to patient characteristics. The population pharmacokinetics of 51Cr-EDTA were analysed using NONMEM to evaluate the influence of each covariate. The formulae derived were then validated using a further 38 patients and compared with those obtained using existing formulae. 51Cr-EDTA clearance (GFR) was positively related to Dubois surface area, negatively related to age, and inversely related to serum creatinine (SCr). Females had lower 51Cr-EDTA clearance than males. The enzymatic method of SCr assay gave more reliable results than the Jaffe colorimetric method. A measure of creatine kinase significantly improved the estimation of GFR. The new formula produced estimates of GFR which were less biased (Mean Prediction Error = -3%) and more precise (Mean Absolute Prediction Error = 12%) than Cockcroft and Gault (-8% and 16%) or Jelliffe (-15% and 19%) estimates. The formulae developed here can be used to provide reliable estimates of GFR, particularly in regard to targeted dosing of carboplatin.

All Half-Lives Are Wrong, But Some Half-Lives Are Useful

The half-life of a drug, which expresses a change in concentration in units of time, is perhaps the most easily understood pharmacokinetic parameter and provides a succinct description of many concentration-time profiles. The calculation of a half-life implies a linear, first-order, time-invariant process. No drug perfectly obeys such assumptions, although in practise this is often a valid approximation and provides invaluable quantitative information. Nevertheless, the physiological processes underlying half-life should not be forgotten. The concept of clearance facilitates the interpretation of factors affecting drug elimination, such as enzyme inhibition or renal impairment. Relating clearance to the observed concentration-time profile is not as naturally intuitive as is the case with half-life. As such, these 2 approaches to parameterising a linear pharmacokinetic model should be viewed as complementary rather than alternatives. The interpretation of pharmacokinetic parameters when there are multiple disposition phases is more challenging. Indeed, in any pharmacokinetic model, the half-lives are only one component of the parameters required to specify the concentration-time profile. Furthermore, pharmacokinetic parameters are of little use without a dose history. Other factors influencing the relevance of each disposition phase to clinical end-points must also be considered. In summarising the pharmacokinetics of a drug, statistical aspects of the estimation of a half-life are often overlooked. Half-lives are rarely reported with confidence intervals or measures of variability in the population, and some approaches to this problem are suggested. Half-life is an important summary statistic in pharmacokinetics, but care must be taken to employ it appropriately in the context of dose history and clinically relevant pharmacodynamic end-points.

The characteristics of patient satisfaction measures

Information on patient satisfaction is considered a way of including patients' perspectives in the planning and assessment of services. The study of patient satisfaction is a relatively new field, and despite the surge in popularity and use of satisfaction measures during the past three decades, different issues remain to be explored. This is not meant to dissuade clinicians from using satisfaction measures, but rather to allow them to proceed in a thoughtful way, recognizing what these measures can reasonably show us about patients' perceptions of the care and treatment interventions they receive. The proposed approach to classifying the characteristics of patient satisfaction measures should help to highlight potential reasons for variation in results when satisfaction measures perform differently and will be of value if it increases the specificity with which clinicians select measures to achieve their purposes.

The resolution of fetal hydrops using combined maternal digoxin and dexamethasone therapy in a case of isolated complete heart block at 30 weeks gestation

The development of hydrops fetalis in cases of isolated complete heart block is associated with a very poor prognosis. Various pharmacological strategies have been proposed, involving both direct fetal access and transplacental therapy, with inconsistent results in small numbers of subjects. The optimal antenatal management will remain uncertain until multicentre controlled trials are organised. We report the complete resolution of fetal hydrops at 30 weeks of gestation using combination of maternal digoxin and dexamethasone therapy, despite persistence of the complete heart block. A Caesarean section was performed at 37 weeks of gestation due to evidence of fetal intrauterine growth restriction. The baby girl is now 8 months of age and remains well, with a heart rate of 45-50 beats per minute on no medication and without pacing.

Assessing physical disability in children with spina bifida and scoliosis

The purpose of this study was to develop a valid and reliable questionnaire to assess physical disability related to the spine in children with spina bifida and scoliosis and their families. Eighty-eight items were generated from a review of the literature and interviews with clinicians, parents, and children with spina bifida and scoliosis. Items were reviewed by 40 children and ranked. After eliminating redundant items, the top 25 items were formatted into a self-administered questionnaire. The questionnaire, completed 2 weeks apart, demonstrated "excellent" test-retest reliability (intraclass correlation coefficient = 0.88). Construct validity was established by high correlation with a validated scale of overall disability: the Activities Scale for Kids (r = 0.86, p < 0.01) and by correlations with global assessment of function. In conclusion, the Spina Bifida Spine Questionnaire is a valid and reliable questionnaire and can be used to assess the outcomes of treatment for children with spina bifida and scoliosis.

The use of bone scan to investigate back pain in children and adolescents

Children with back pain frequently undergo detailed investigation because of the perception that a high percentage will have a treatable spinal condition. The purposes of this study was (i) to determine the percentage of children with disabling back pain presenting to our institution who had a diagnosis (i.e., to explain their back pain), (ii) to evaluate the clinical markers that should alert clinicians to underlying pathology, (iii) and to determine the prognosis of children with back pain and no specific diagnosis. This study was a retrospective analysis of consecutive children undergoing single-photon emission computed tomography for a primary complaint of back pain. Data collection included chart review, radiographic analysis, and clinical follow-up with the Roland and Morris scale for pain and disability. Two hundred and seventeen patients with an average age of 13 years (range, 2.7-17.7) were reviewed on average 4.4 years after presentation (range, 1.1-7.2 years). One hundred and seventy children (78.3%) had no specific diagnosis to explain their back pain, 15 children (6.9%) had spondylosis, 10 children (4.6%) had tumor, and the remaining 22 children (10.1%) had various diagnoses including infection, Scheuermann's kyphosis, herniated disc, kidney disease, facet arthritis, degenerative disc disease, congenital anomalies, and tethered cord. Factors associated with positive diagnoses were constant pain and male gender. Night pain, constant pain, and duration of symptoms <3 months were associated with the diagnosis of a tumor. Although the majority of children presenting with persistent back pain had no demonstrable cause, of 132 contactable patients 94 (71%) had persisting pain at the time of clinical follow-up. In conclusion, the majority of children with disabling back pain has no demonstrable cause and the majority will continue to have pain years after initial presentation.

Outcome after prenatal diagnosis of hypoplastic left-heart syndrome: a case series

BACKGROUND

Traditionally, after prenatal diagnosis of hypoplastic left-heart syndrome (HLHS) couples have been offered termination of pregnancy or comfort care. Success of postnatal surgical options such as the Norwood procedure have been associated with survival of up to 60%. Whether survival is affected by the congenital anomaly being identified prenatally or postnatally remains uncertain.

METHODS

We reviewed all cases of prenatally diagnosed HLHS referred to the Fetal Medicine Unit at Birmingham Women's Hospital over 6 years between 1994 and 1999.

FINDINGS

87 cases of HLHS were referred at a median gestational age (95% CI) of 23 (19-37) weeks. Of these, 53 (61%) chose prenatal karyotyping. The overall frequency of abnormal karyotype was found in seven of 59 cases (12%) and associated structural anomalies in 18 of 87 (21%). After counselling, 38 of 87 couples (44%) chose termination of pregnancy. Of the remaining 49 fetuses, 11 (23%) were not considered for postnatal surgery because of parental choice and they died after compassionate care. Of the 36 babies who had surgery postnatally, 12 survived (33%). We recorded a survival rate of 38% for the stage-1 Norwood procedure in the prenatally diagnosed HLHS in our centre. These data suggest that at the point of prenatal detection, the overall survival rate for fetuses with HLHS is 25% (if terminated pregnancies are excluded).

INTERPRETATION

Fetal echocardiography allows early diagnosis of HLHS and gives clinicians the opportunity to triage this group dependent on prenatal findings, including karyotyping and the exclusion of other structural anomalies. These prospective data provide up-to-date information on the basis of which parents can make decisions.

Balloon angioplasty in infants with aortic obstruction after the modified stage I Norwood procedure

BACKGROUND

The incidence of coarctation after stage I Norwood procedure varies between 11% and 37%, and it contributes to late death after this operation. We describe the incidence and report the results of percutaneous balloon angioplasty of neoaortic arch obstruction in patients after the modified Norwood procedure for hypoplastic left heart syndrome (HLHS).

METHODS

During a period of 5 years, 136 patients (94 male, 42 female) underwent a first stage modified Norwood procedure for HLHS. All 95 survivors (69.8%) underwent cardiac catheterization before the second stage. Neoaortic arch obstruction was diagnosed on documentation of a peak systolic gradient of >10 mm Hg across the arch associated with angiographic evidence of localized narrowing of the aortic lumen.

RESULTS

Twenty-one (22.1%) of the 95 survivors were documented to have neoaortic arch obstruction. Seventeen patients underwent percutaneous balloon angioplasty for the relief of the neoaortic arch obstruction. The predilatation peak gradient across the arch was reduced significantly by angioplasty from 28.6 +/- 16.9 mm Hg (range 10 to 73 mm Hg) to 5.3 +/- 5.2 mm Hg (range 0 to 19 mm Hg) (P <.001). A final gradient <10 mm Hg or <70% of the starting gradient was considered a success.

CONCLUSION

The absence of serious sequelae after the procedure or need for reintervention, as shown by our study, makes balloon angioplasty an effective technique and the treatment of choice for the relief of recoarctation of the neoaortic arch in patients with staged palliation of HLHS.

Evaluating the outcome of treatment. Shouldn't We be asking patients if they are better?

Increasingly clinicians and investigators are recognizing the need to include patients in the assessment of therapy. Patient-based assessments, such as measures of health status or health-related quality-of-life, require patients to rate themselves on a fixed number of questions. Because patients come to their doctors with unique, different, and individual concerns, the concern is that commonly used scales with a fixed number of questions might be excluding important individual concerns or including issues irrelevant to individual patients. Clinicians usually do not rely on health status questionnaires in routine practice to judge the success of therapy, but ask patients directly if they are better. Despite this fundamental interchange between patients and clinicians, relatively little attention has been directed towards the specification, measurement, and quantification of patients' individual concerns. Patient-specific measures are a particular type of measure which allow patients to state their individual concerns, and weight their relative importance. Because we are often trying to address with treatment the concerns of individual patients, patient-specific outcomes would provide us a standardized method useful in research and clinical practice of asking patients whether they are better.

The treatment of femoral shaft fractures in children: a systematic overview and critical appraisal of the literature

OBJECTIVE

Through a critical systematic overview of the literature on the treatment of pediatric femoral shaft fractures to determine if any method of treatment can be recommended over others.

DATA SOURCES

A MEDLINE search was performed for all cohort and randomized clinical trials for the years 1966 to 1996.

STUDY SELECTION

Of 1217 identified articles, 15 cohort studies (where 2 or more treatments were compared in the same study) reported the treatment of children with femoral fractures.

DATA EXTRACTION

Information was abstracted and articles rated for quality blind to author, institution and journal.

DATA SYNTHESIS

Children having early application of a hip spica cast had an average hospital stay of 11 days (range from 5 to 29 days), average charges of $5784 (range from $590 to $11,800), average rates of limb-length discrepancy (greater than 2 cm) of 3% (range from 0 to 25%), angulatory malunion rates (greater than 10 degrees) of 8% (range from 0 to 19%), and rotational malunion rates (greater than 10 degrees) of 13% (range from 0 to 5%). The costs and malunion rates of early application of a hip spica cast were lower than for traction. Internal fixation (including intramedullary nails) had low angulatory malunion rates compared with early application of a hip spica cast but higher over-lengthening rates (greater than 2 cm) of 25% (range from 5% to 100%) and mean rotational malunion rates (greater than 10 degrees) of 25% (range from 11% to 32%).

CONCLUSION

Early application of a hip spica cast had lower costs and malunion rates than traction.

The reliability and validity of the self-reported patient-specific index for total hip arthroplasty

BACKGROUND

The Patient-Specific Index is unique in that it reflects how individual patients weigh concerns in rating the outcome of total hip arthroplasty. The Patient-Specific Index was originally administered by an interviewer, which is not always feasible and can be costly. The purposes of the present study were (1) to create a self-reported version of the Patient-Specific Index, (2) to determine the reliability of this new self-reported version, and (3) to determine the relationship between the scores on the new self-reported version and those on the original interviewer-administered version.

METHODS

A self-reported version of the Patient-Specific Index was developed, and a pilot test was performed on ten patients. Patients who were scheduled for a total hip arthroplasty or who had recently had a total hip arthroplasty were eligible for the reliability and validity testing. A copy of the new self-reported Patient-Specific Index was mailed to the patients, and they completed it independently. The patients' ratings of the importance and severity of twenty-four concerns prior to total hip arthroplasty were added together to create a summary Patient-Specific Index score. To determine test-retest reliability, patients completed the self-reported Patient-Specific Index a second time, two weeks later. To determine criterion validity, participants also completed the interviewer-administered Patient-Specific Index.

RESULTS

Fifty-five patients completed the study. The random-effects intraclass correlation test-retest coefficient was 0.79 (greater than 0.75 represents excellent reliability). The mean Patient-Specific Index scores on the self-reported version and on the interviewer-administered version were 173 and 165 points, respectively (Student t test, p = 0.45). The self-reported Patient-Specific Index was concordant with the interviewer-administered Patient-Specific Index (intraclass correlation coefficient, 0.78).

CONCLUSIONS

We concluded that a self-reported version of the Patient-Specific Index, which focuses on the concerns of individuals, is reliable and has criterion validity compared with an interviewer-administered version.

Differences between men and women in the rate of use of hip and knee arthroplasty

BACKGROUND

Previous studies suggest that, for some conditions, women receive fewer health care interventions than men. We estimated the potential need for arthroplasty and the willingness to undergo the procedure in both men and women and examined whether there were differences between the sexes.

METHODS

All 48,218 persons 55 years of age or older in two areas of Ontario, Canada, were surveyed by mail and telephone to identify those with hip or knee problems. In these subjects, we assessed the severity of arthritis and the presence of coexisting conditions by questionnaire, documented arthritis by examination and radiography, and conducted interviews to evaluate the subjects' willingness to undergo arthroplasty. The potential need for arthroplasty was defined by the presence of severe symptoms and disability, the absence of any absolute contraindications to surgery, and clinical and radiographic evidence of arthritis. The estimates of need were then adjusted for the subjects' willingness to undergo arthroplasty.

RESULTS

The overall response rates were at least 72 percent for the questionnaires and interviews. As compared with men, women had a higher prevalence of arthritis of the hip or knee (age-adjusted odds ratio, 1.76; P<0.001) and had worse symptoms and greater disability, but women were less likely to have undergone arthroplasty (adjusted odds ratio, 0.78; P<0.001). Despite their equal willingness to have the surgery, fewer women than men had discussed the possibility of arthroplasty with a physician (adjusted odds ratio, 0.63). The numbers of people with a potential need for hip or knee arthroplasty were 44.9 per 1000 among women and 20.8 per 1000 among men. After adjustment for willingness to undergo the procedure, the numbers were 5.3 per 1000 for women and 1.6 per 1000 for men.

CONCLUSIONS

There is underuse of arthroplasty for severe arthritis in both sexes, but the degree of underuse is more than three times as great in women as in men.

Measurement properties of the activities scale for kids

The Activities Scale for Kids (ASK) is a self-report measure of childhood physical disability, that has excellent reliability (ICC = 0.97). The purpose of this study was to assess further the ASK's measurement properties. ASK questionnaires were completed by 200 children with musculoskeletal limitations (mean age, 10.1 years). Rasch analyses confirmed that all items measured the same construct and supported aggregation of a summary score. Validity of the ASK was demonstrated by a correlation of 0.81 (P<0.0001) with parent-reported Childhood Health Assessment Questionnaire scores; a significant difference in scores according to clinicians' global ratings of disability (P<0.0001), and a correlation of 0.92 (P<0.0001) with clinician-observation. The ASK showed minimal ceiling effects, no floor effects, and changed by 1.73 standard deviation units after clinically important change. The ASK is a valid and responsive outcome measure that permits 5- to 15-year-old children physical functioning in the community to be assessed accurately by mail. The quality of this measure will enable clinical studies to measure outcome not only in a way that is relevant to patients, but also in a way that is sensitive to small amounts of change and is practical and inexpensive.

The relationship between aerobic exercise capacity and circulating IGF-1 levels in healthy men and women

OBJECTIVES

To determine whether aerobic capacity is associated independently with insulin-like growth factor-I (IGF-1) levels in healthy community-dwelling men and women.

SETTING

The Baltimore Longitudinal Study on Aging (BLSA).

DESIGN

A cross-sectional analysis of data from the population-based cohort of the Baltimore Longitudinal Study of Aging (BLSA).

PARTICIPANTS

We studied 181 men and 92 women aged 20 to 93 years, volunteers in the Baltimore Longitudinal Study on Aging (BLSA). Subjects were free of endocrine, renal, hepatic, gastrointestinal, or cardiac diseases, and they were taking no medications known to interfere with the growth hormone-IGF-1 axis.

MEASUREMENTS

All subjects underwent a single measurement of serum IGF-1 in the fasting state, as well as peak VO2 determinations during maximal treadmill exercise testing performed within one visit of the IGF-1 determination. Dual energy X-ray absorptiometry (DEXA) scans were performed in a subset of 171 subjects (64 women and 107 men) for determination of fat free mass (FFM).

RESULTS

In the pooled group of women and men, univariate regression analysis revealed that age was correlated strongly with decreasing IGF-1 levels (r = -0.53, P < .001) and with peak VO2r = -0.56, P < .001). IGF-1 levels were also significantly correlated with peak VO2 (r = 0.29, P < .001). There were no significant gender-related differences in these relationships. On multivariate analysis, age (beta = -0.54, P < .001), but not peak VO2 (P = -0.01, P = .840), remained strongly associated with IGF-1 levels. After adjustment of peak VO2 for FFM in subjects with DEXA scans, results were similar.

CONCLUSIONS

These findings indicate that although both peak aerobic capacity and circulating IGF-1 levels decline with age, aerobic capacity is not independently related to circulating IGF-1 in healthy men and women across the adult life span.

Early repolarization: an electrocardiographic predictor of enhanced aerobic fitness

The presence or absence of early repolarization on the electrocardiogram at rest was correlated with aerobic exercise capacity in healthy volunteers from the Baltimore Longitudinal Study of Aging. Patients with early repolarization had both longer treadmill exercise duration and higher peak oxygen consumption than age-and gender-matched control subjects.