DXA-Generated Z-Scores and T-Scores May Differ Substantially and Significantly in Young Adults

Central dual-energy X-ray absorptiometry (DXA) is the gold standard for non-invasive measurement of bone mineral density (BMD). Using this value and subject demographics, DXA software calculates T-scores and Z-scores. Professional society guidelines for the management of osteoporosis are based on T-scores and Z-scores, rather than on the actual BMD value. Although one expects T-scores and Z-scores to be very similar in young men and women for any given BMD measurement, little literature exists on this issue. Our clinical experience shows that some younger adult individuals (premenopausal women and men younger than 50 yr) have larger than expected difference between their DXA T-score and Z-score. This cross-sectional study evaluates the extent of this discordance between Z-scores and T-scores in a sample of 4275 men and women aged 20–49 yr. All subjects were scanned by central DXA using equipment manufactured by GE Lunar, GE, Madison, WI, or Hologic, Inc., Bedford, MA. Significant differences between Z-scores and T-scores were seen within individuals at the lumbar spine, total hip, femoral neck, and trochanter (p value < 0.001) for both DXA systems. Although these differences were less than half a standard deviation (SD) in most instances, the magnitude of difference was substantial at times, being 1 or more SD in up to 11% of cases (range: −1.95 to +1.54 SD). The smallest differences were seen at the total hip and the largest differences were seen at the femoral neck for both technologies. This is in part because there is no single standard Z-score definition, resulting in different methods of calculation across, and even within, DXA manufacturers. Standardization of Z-score definition and method of calculation is indicated. DXA Z-scores should be interpreted with caution in men and women aged 20–50 yr.     

Mortality rate after hip hemiarthroplasty: analysis of risk factors in 299 consecutives cases

Abstract The femoral neck fracture is actually the most important traumatic event in the elderly, because of its high rate and terrible complications. We reviwed clinical records of 314 patients treated in our institution with a bipolar implant for femoral neck fracture. At a mean follow-up of 5 years, 15 patients (4.8%) were lost to followup so data for 299 patients was studied to identity factors associated with mortality. Ten predictor variables were examined: age, sex, waiting time for surgery, pulmonary dysfunction, fracture etiology, and comorbidity with ischemic heart disease, and heart failure, hypertension, cerebrovascular disease, and chronic renal failure. Cumulative mortality rate during the first 6 months was 19% (55 of 299 patients) and in the first year it was 25% (76 of 299). At logistic regression analysis, mortality was associated with age, male gender, waiting period for surgery and presence of neoplastic disease or pathological fracture. Waiting for surgery was a significant factor for mortality at 6, 12 and 24 months: patients surgically treated in the first 24 hours had lower mortality than those who waited longer. The risk of mortality in the first 6 months doubled for an age increase of 12 years, while mortality within 2 years doubled for an age increase of 9 years. Although the motality rate after surgery for femoral neck fracture was high in the first year (25%), it dropped off in successive years to levels observed in a healthy population. Thus, we agree with the literature that femoral fracture is a risk factor for survival only in the first year after trauma, above all in the elderly.     

Quality assurance, efficiency indicators and cost-utility of the evaluation workup for liver transplantation.

We report the results of a retrospective review of the outpatient pretransplantation workup for United Network for Organ Sharing (UNOS) 3 patients adopted at a liver transplantation (LT) center and illustrate the efficiency indicators used for quality evaluation and cost-analysis. A single-center, pre-LT evaluation workup was performed on an outpatient basis at a cost per patient evaluation of 2,770 Euros (). Objective measures were: the number of patients admitted to and excluded from each phase of the algorithm; the rate of patients admitted to pre-LT evaluation out of the total of referred patients (the referral efficiency rate); the rate of waitlisted patients out of those admitted to pre-LT evaluation (the evaluation efficiency rate); the rate of waitlisted patients out of those referred for LT (the process efficiency rate); and the cost per waitlisted patient, as the ratio of the cost per patient evaluation to the evaluation efficiency rate. From January 1, 1996, to October 1, 2004, 1,837 patients were referred for LT on an outpatient basis. Based on preemptive evaluation of the available clinical data, 412 patients (22.4%) were excluded from pre-LT evaluation and 1,425 (77.6%) were admitted to preliminary consultation. Among these, 603 (42.3%) were excluded from and 822 (57.7%) were admitted to pre-LT evaluation with a referral efficiency rate of 44.7% (822 of 1,837). Out of the patients evaluated for LT, 484 were waitlisted with a cost-utility and evaluation efficiency rate of 58.8% each (484 of 822). Of the 1,837 patients originally addressed for LT 484 were waitlisted, yielding a process efficiency rate of 26.3% (484 of 1,837) and a cost per waitlisted patient of 4,710.8. In conclusion, the 3 indicators allowed monitoring of the efficiency of the pre-LT evaluation algorithm. The current process efficiency rate at our center is low (26.3%), but avoiding early referrals we might increase it to 31.6%, with a 12% net saving on costs per waitlisted patient (from 4,710.8 to 4,165.4).     

MM-CK subtypes diagnose reperfusion early after myocardial infarction

Isoelectric focusing (IEF) was used to analyze the serum MM-CK isoenzyme subtypes in 16 patients receiving streptokinase (SK) for attempted coronary thrombolysis early after acute myocardial infarction. Twelve patients had revascularization documented by serial coronary angiograms (Group I); in four patients, angiography documented no such reperfusion (Group II). The data also were compared with a previously reported group of 8 patients who did not receive streptokinase (Group III). Total and MB-CK activity, as well as the MM-CK isoenzyme subtypes MM3-CK, MM2-CK, and MM1-CK tended to rise earlier and peak earlier in Group I compared with Group II; serum MM3-CK, the predominant subtype in myocardium, however, definitely peaked earlier in Group I (8.65 +/- 2.07 hr) compared with Group II (18.50 +/- 6.67 hr) (p less than 0.001). Soon after its release from myocardium, MM3-CK is converted in the serum to MM2-CK and eventually to MM1-CK; thus, the MM3-CK:MM1-CK ratio amplifies the time course of subtype conversion. The MM3-CK:MM1-CK activity ratio peaked earlier in Group I (5.51 +/- 0.97 H) compared to Group II (10.74 +/- 3.28 hr) (p less than 0.01), and peaked even earlier than MM3-CK (p less than 0.007) in both Groups I and II. Thus, the time course of the MM3-CK:MM1-CK ratio separates those patients who reperfuse when early SK is used after acute myocardial infarction from those who do not, and does it significantly earlier than the other enzymatic parameters of cellular necrosis, total CK, and MB-CK.     

The hospital as an enterprise: management strategies

After introducing the context in which health systems exist in developing as well as in industrialized countries, the author describes the role that hospitals are expected to play as 'enterprises'. The rationale behind such a role is explored and the experience so far available discussed. Evidence from several developing countries suggests caution and tends to discourage radical and indiscriminate introduction of market‐oriented reforms, which international donors seem to be spearheading in Africa's health systems. It is likely, however, that a limited, gradual introduction of selected elements of these reforms (such as some aspects of contracting out, managerial decentralization, the split between purchasing and providing functions) may find its place and eventually have a positive impact on the performance of the health systems. But the 'mystique of markets' must not be allowed to deprive public hospitals of the sense of social utility and of the caring ethos which are essential requisites of a meaningful and effective public health system.     

Role of DAT‐SPECT in the diagnostic work up of Parkinsonism

The diagnosis of idiopathic Parkinson's disease (PD) can be achieved with high degrees of accuracy in cases with full expression of classical clinical features. However, diagnostic uncertainty remains in early disease with subtle or ambiguous signs. Functional imaging has been suggested to increase the diagnostic yield in parkinsonian syndromes with uncertain clinical classification. Loss of striatal dopamine nerve terminal function, a hallmark of neurodegenerative Parkinsonism, is strongly related to decreases of dopamine transporter (DAT) density, which can be measured by single photon emission computed tomography (SPECT). The use of DAT‐SPECT facilitates the differential diagnosis in patients with isolated tremor symptoms not fulfilling PD or essential tremor criteria, drug‐induced, psychogenic and vascular Parkinsonism as well as dementia when associated with Parkinsonism. This review addresses the value of DAT‐SPECT in early differential diagnosis, and its potential as a screening tool for subjects at risk of developing PD as well as issues around the assessment of disease progression. © 2007 Movement Disorder Society     

Top-down and bottom-up processes in the extrastriate cortex of cirrhotic patients: an ERP study.

OBJECTIVE: This study aims to evaluate the efficiency of top-down and bottom-up processes in the extrastriate cortex of cirrhotic patients without overt hepatic encephalopathy (HE). METHODS: Reaction times (RTs), accuracy and event-related potentials (ERPs) were recorded during the execution of a visual Simon task in 17 cirrhotic patients and 10 healthy controls. Amplitude and latency of the P1 and N1 (indexes of bottom-up processes) and of the N2pc (index of top-down processes) were measured. RESULTS: Patients were slower than controls, and patients with minimal HE (MHE) were slower than patients without MHE. The distribution analysis of RTs showed that the Simon effect decays with slower RTs in all the groups and that the shape of the distribution was different in MHE patients. No differences were found between cirrhotic patients and controls for P1 and N1 amplitude and latency. In contrast, N2pc latency was delayed in cirrhotic patients compared to controls independently of MHE. CONCLUSIONS: In the extrastriate cortex of cirrhotic patients without HE, top-down processes are altered whereas bottom-up processes are preserved. SIGNIFICANCE: The analysis of exogenous and endogenous visual components of ERPs provides a model to study the functional dissociation between top-down and bottom-up processes inside the extrastriate cortex.     

Transient hypoparathyroidism following thyroidectomy: a prospective study and multivariate analysis of 604 consecutive patients.

OBJECTIVE: The purpose of this study was to identify the risk factors for postoperative transient hypoparathyroidism in a group of patients undergoing thyroid surgery. STUDY DESIGN: A prospective study was conducted on 604 patients undergoing thyroid surgery. SUBJECTS AND METHODS: Gender, final diagnosis, extent of resection, biology of pathology, intrathoracic involvement, surgery for recurrent multinodular goiter, and presence and number of parathyroid glands in a surgical specimen were analyzed as risk factors for postoperative transient hypoparathyroidism. The chi-square test and a logistic regression analysis were applied. RESULTS: On logistic regression analysis, only the extent of surgery constituted an independent variable for transient hypoparathyroidism (P = 0.001). CONCLUSION: The extent of surgery to central and/or lateral neck lymph nodes is responsible for a high rate of transient hypoparathyroidism owing to a high probability of unplanned parathyroidectomy or parathyroid gland devascularization.     

Effectiveness of neonatal transport in New York city in neonates less than 2500 grams—A population study

In the past two decades, there has been a gradual trend to regionalization of perinatal care, categorization of hospitals and transport services for neonatal health care. The literature alludes to both beneficial and deleterious effects of neonatal transport (T) but no controls such as a matched nontransport (NT) population have been utilized to date.The major goal of this study was to evaluate the effect of neonatal transport from Level I and II high risk 2500 gm. neonates (born in NYC in one calendar year, 1979) compared to a cohort nontransported population matched for hospital of birth, weight, race, sex and risk. All transported 2500 gm. from Level I and II (n=328) were studied and a stratified random sample of the nontransported (NT) infants 2500 gm. from these same hospitals (n=2042) was used for comparison. The principle outcome variable was survival. The major conclusion of this study is that in Level I and II hospitals the transport group had a significantly increased survival in infants who were sick (Apgar <6) compared to cohorted nontransported controls. Interhospital differences in survival were noted among Level I and II but not seen in the subdivisions of (A) and (B) hospitals.Angelo Ferrara, M.D., Ph.D., is Professor, Pediatrics, NYU Medical Center, New York, N.Y.: Melvin Schwartz, M.D., was Research Professor, Environmental Medicine, NYU Medical Center, New York, N.Y.; Helen Page, R.N., M.P.A., is Quality Assurance Reviewer, Manhattan Eye, Ear, Throat Hospital, New York, N.Y.: Morton Israel, M.A., is Research Scientist, Health Resources Administration, City of N. Y., New York, N.Y.; Yucel Atakent, M.D., M.S., is Clinical Associate Professor, NYU Medical Center, New York, N.Y.; C.E. Smith, Ph.D., is President, Health Policy Analysis & Accountability Network, Inc. (HPAAN), Edgewood, New Mexico; Leon Landovitz, Ph.D., is Vice President, Management Information Systems, Healthways System Inc., Islin, N.J.Supported by NCHSR Grant #5-R018-HSO3832