Randy L. Carter

Patency of autogenous and polytetrafluoroethylene upper extremity arteriovenous hemodialysis accesses: a systematic review

OBJECTIVEnPatency rates for autogenous accesses are presumed to be better than for polytetrafluoroethylene (PTFE) accesses, although the strength of the supporting evidence is limited. We undertook this study to test the hypothesis that patency rates for upper extremity autogenous hemodialysis arteriovenous accesses in adults are superior to those for PTFE counterparts.nnnMETHODSnA systematic review of relevant literature and meta-analysis of the patency data were performed. Studies were considered acceptable if patency data were reported by either life table or Kaplan-Meier method, including number of patients at risk.nnnRESULTSnThe thirty-four studies that satisfied the inclusion criteria were composed predominantly of case series or nonrandomized controlled studies; no randomized, controlled studies comparing autogenous and PTFE accesses were included. The primary patency rate for autogenous accesses was 72% (95% confidence interval [CI], 70%-74%) at 6 months and 51% (95% CI, 48%-53%) at 18 months, and the corresponding primary patency rate for PTFE accesses was 58% (95% CI, 56%-61%) and 33% (95% CI, 31%-36%), respectively. The secondary patency rate for autogenous accesses was 86% (95% CI, 84%-88%) at 6 months and 77% (95% CI, 74%-79%) at 18 months, and the corresponding secondary patency rate for PTFE accesses was 76% (95% CI, 73%-79%) and 55% (95% CI, 51%-59%), respectively.nnnCONCLUSIONSnThe patency rate for autogenous upper extremity arteriovenous hemodialysis accesses in adults is superior to that for PTFE counterparts, although the overall quality of the studies in the meta-analysis was less than ideal. Randomized, controlled studies to further examine the differences in outcome between these two access types are necessary.

Mixed-effects nonlinear regression for unbalanced repeated measures

Repeated measures data, such as clinical pharmacokinetic data, growth data, and dose-response data, are often inherently nonlinear with respect to a given response function and are frequently incomplete and/or unbalanced. Nonlinear random-effects models together with a variety of estimation procedures have been proposed for the analysis of such data. This paper is concerned with a straightforward procedure for estimating and comparing the parameters of a generalized mixed-effects nonlinear regression model. The asymptotic properties of the proposed estimators are given and large-sample tests of hypothesis provided. The results are applied to in vitro data on the water transport kinetics of hemodialyzers used in the treatment of patients with chronic renal failure.

A controlled comparison of two treatments for nocturnal enuresis.

This study assessed change in the frequency of primary nocturnal enuresis as produced by either behavioral conditioning with a urine alarm, pharmacotherapy with imipramine hydrochloride, or assignment to a clinical waiting list. The study also investigated the effect of treatment method and outcome on subjects level of emotional and behavioral adjustment. An attempt was made to identify pretreatment predictors of treatment outcome and premature withdrawal from the treatment program. The results indicated a significantly more effective outcome for the conditioning approach. Comparison of pre- and post-treatment measures of adjustment provided insufficient evidence to support the hypotheses that either change in the frequency of nighttime wetting or the method of treatment received would influence the subjects level of emotional and behavioral adjustment. The enuresis tolerance scale was found to be a highly significant predictor of early termination from conditioning treatment.

A prospective analysis of stress and fatigue in recurrent low back pain

&NA; The purpose of the present study was to determine whether patients with recurrent low back pain display a different pattern of mood fluctuations across days than matched healthy controls and whether these mood states are related to pain occurrence and/or magnitude using a prospective design. The questions addressed are whether mood states prior to a pain episode are associated with the episode or whether mood relates to pain as a secondary reaction. Similarly, the relationship between mood state recorded prior to, during or following pain and magnitude of pain experienced was investigated. Thirty‐three ambulatory chronic low pack pain patients and an equivalent group of asymptomatic controls matched for age, sex, socioeconomic status, and reported activity level monitored mood state (anxiety, tension, depression, anger, vigor, fatigue, confusion) and pain before breakfast, at 4 p.m. and at bedtime for 14 consecutive days. Groups were successfully matched. Analyses revealed significantly higher levels of tension, anxiety and fatigue and lower levels of vigor in the pain cases. No mood state was predictive of pain onset but fatigue was associated with pain 24 h following pain, indicating fatigue as secondary to pain. While mood state recorded prior to or following pain was unable to predict magnitude of pain, fatigue was associated with the level of pain experienced during the pain episode itself. The findings reveal a pattern of anxiety, tension and fatigue where fatigue is associated with increased pain during the pain episode and is increased 24 h following pain. This fatigue‐pain relationship is superimposed upon a continuous elevation of anxiety and tension. These findings suggest the importance of pain management efforts directed at decreasing patients fatigue levels, and increasing functional endurance while simultaneously reducing anxiety. The results also question the role of negative mood states in the initiation or exacerbation of pain and highlights the influence of physical mood states such as fatigue on pain in low back pain.

Large sample inference in random coefficient regression models

Random coefficient regression models have been used t odescribe repeated measures on members of a sample of n in dividuals . Previous researchers have proposed methods of estimating the mean parameters of such models. Their methods require that eachindividual be observed under the same settings of independent variablesor , lesss stringently , that the number of observations ,r , on each individual be the same. Under the latter restriction ,estimators of mean regression parameters exist which are consist ent as both r→∞and n→∞ and efficient as r→∞, and large sample ( r large ) tests of mean parameters are available . These results are easily extended to the case where not a11 individuals are observed an equal number of times provided limit are taken as min(r) → ∞. Existing methods of inference , however, are not justified by the current literature when n is large and r is small, as is the case i n many bio-medical applications . The primary con tribution of the current paper is a derivation of the asymptot...

Low-dose oral contraceptive usage and coagulation☆

A prospective investigation was initiated to assess the effect of a low-dose oral contraceptive containing 35 micrograms of ethinyl estradiol and 0.4 mg of norethindrone on blood coagulation and fibrinolysis. Twenty-four women were studied before, during, and after one year of treatment. Positive results included an accelerated activated partial thromboplastin time and an increase in fibrinolytic and anticoagulation factors as measured by alpha 1-antitrypsin antigen and plasminogen antigen and activity. Antithrombin III antigen was decreased but its activity was unaffected. There was no evidence of ongoing intravascular coagulation. No patient had a detectable thromboembolic event. In short, one years usage of this low-dose oral contraceptive was not associated with a procoagulant hematologic profile.

Autoantibodies and immunoglobulins among atomic bomb survivors

The purpose of this study was to determine if exposure to atomic bomb radiation affects immune responsiveness, such as the occurrence of autoantibodies and levels of immunoglobulins. Rheumatoid factor, antinuclear antibody, antithyroglobulin antibody, anti-thyroid-microsomal antibody and immunoglobulin levels (IgG, IgM, IgA and IgE) were measured among 2,061 individuals exposed to atomic bomb radiation in Hiroshima and Nagasaki whose estimated doses ranged from 0 to 5.6 Gy. The prevalence and titers of rheumatoid factor were found to be increased in the individuals exposed to higher radiation doses. The IgA level in females and the IgM level in both sexes increased as radiation dose increased, although the effects of radiation exposure were not large. No effect of radiation was found on the prevalence of antinuclear antibody, antithyroglobulin antibody and anti-thyroid-microsomal antibody or on the levels of IgG and IgE.

Behavioral and environmental characteristics of treated and untreated enuretic children and matched nonenuretic controls.

This correlational study investigated possible behavioral, parental, and environmental differences in enuretic children who were either receiving or not receiving treatment for bed-wetting. The subjects wer 5- to 12-year-old children who were nocturnally incontinent at least once a week and physically normal in all other respects. Seventeen of these youngsters were receiving pharmacologic treatment for enuresis (clinical enuretic group) and 20 were not (nonclinical enuretic group). Clinical enuretic children were older and wet more frequently than youngsters whose parents had not sought treatment for this problem. Their fathers more often held blue-collar jobs and their mothers were more intolerant of enuresis than were parents of the nonclinical enuretic sample. These two groups did not differ in number and type of child behavior problems, number of life-stress events, age toilet training commenced, or parental child-rearing practices employed. However, enuretic youngsters displayed more conduct problems and immature behavior than their nonenuretic counterparts. Mothers of enuretic youngsters applied more rule-oriented child-rearing practices than mothers of nonenuretic controls. There were no differences between the enuretic and nonenuretic groups in number of early-life stressful events or the age at which toilet training commenced.

Handedness and aphasia: an inferential method for determining the mode of cerebral speech specialization.

Abstract This paper presents a method to infer the cerebral mode of speech in the left- and right-handed. The method is applied to the known reports on the incidence of aphasia following a unilateral brain injury in adults (1935–1973) [1]. Two different models were found. In the left-handed, a complex model of unilateral (left=0.24, right=0.00) and bilateral speech (0.76) was inferred. In the right-handed, a less complex model of unilateral speech specialization (left=0.95, right=0.05) was inferred.

Rheumatoid vasculitis: diagnostic and therapeutic decisions

SummaryRheumatoid vasculitis is an uncommon but potentially catastrophic complication of RA. There are few extensive experiences recorded in the current literature and there is no consensus regarding the clinical features, laboratory findings, histologic pattern, prognosis, or appropriate management of this syndrome. We therefore surveyed 1,947 North American ARA members for their perceptions of rheumatoid vasculitis. Fourhundred twenty-eight surveys were returned, of which 290 were suitable for analysis. The majority of respondents were within 10 years of fellowships and were even distributed among private practice, and parttime and full-time academic positions. The respondents saw 15–50 rheumatoid arthritis (RA) patients weekly and less than five RA vasculitis patients annually. The majority correctly diagnosed two actual and complex case histories from patients with and without autopsy-proven vasculitis. Respondents associated the following features most strongly with rheumatoid vasculitis — mononeuritis multiplex, digital gangrene, digital ischemic lesions, nailfold ischemic lesions, non-healing leg ulcers, palpable purpura, fingertip nodules, sensory neuropathy, scleromalacia perforans, high titer rheumatoid factor, positive visceral angiography, cryoglobulinemia, hypocomplementemia, circulating immune complexes, and histologic necrotizing vasculitis or vascular transmural neutrophilia. Digital lesions or sensory neuropathy alone were not viewed as portending an ominous prognosis by most respondents and would have been treated with nonsteroidal anti-inflammatory drugs, antimalarials, gold salts, or D-penicillamine. Other clinical manifestations considered as reflecting rheumatoid vasculitis (gangrene, mononeuritis multiplex, ulcers) were thought to worsen prognosis and would have been managed more often with corticosteroids, D-penicillamine, cytotoxic agents or plasmapheresis. Rheumatoid vasculitis is viewed as a heterogeneous group of syndromes with varying clinical and histopathologic features, which have different prognostic implications, and therefore should be managed differently. While these data do not substitute for an extensive recorded series of patients, they provide useful information about community perceptions of an uncommon but difficult clinical problem. They identify the need for additional data to examine the validity of these attitudes.