Practical applications of decision analysis

The number and complexity of available tests and therapies is expanding and financial resources are shrinking. Clinicians must now consider how to give the best care while limiting health expenses. Decision analysis is a tool used to guide clinicians in the practice of medicine, and to supplement and enhance intuitive decision making based on clinical experience.     

Sentinel health events surveillance in diabetes. Deaths among persons under age 45 with diabetes

The pilot study for a sentinel health events surveillance system for deaths among persons under age 45 with diabetes was conducted in six states in 1984 and 1985. Two hundred and thirty-three events were identified. Information from death certificates, physicians, and families revealed that 22% died from acute complications of diabetes and 53% from chronic complications. Blood pressure measurement and urinalysis testing had been performed in the last year for almost all of the decedents, but other preventive practices were reported less frequently. Hypertension was present in 57% and of those, was not controlled in 73%. Forty-four percent were cigarette smokers at the time of death. Agreement between physicians and families was generally higher for clinical conditions than for care practices. This surveillance system appears to yield information about the health care of persons with diabetes not readily available from other sources, although modifications may be necessary before implementation.     

Internal eye wall resection in the management of uveal melanoma

Twenty patients with presumed uveal melanoma underwent internal eye wall resection. It was the primary procedure in 13 patients who had tumours within 2 disc diameters of the optic nerve head and was combined with external resection in the remainder. Malignant melanoma was confirmed histologically in 15 patients; the diagnosis was a benign tumour in the other 5. The length of follow-up ranged from 2 to 37 (mean 19) months. In all cases the retina was completely attached at the time of last examination. The visual acuity ranged from 20/40 to hand movements; nine patients had an acuity of 20/400 or better. At the time of writing no metastatic disease or local recurrence had developed in any of the 15 patients in whom malignant melanoma was diagnosed.     

Transconjunctival reopening of an occluded filtration fistula with the Q-switched Neodymium-YAG laser

The Q-switched neodymium-YAG laser was used via a transconjunctival approach to reopen a failed filtering bleb, 6 weeks after a primarily successful trabeculectomy had failed. One day after treatment, the intraocular pressure had decreased from 34 mm Hg to 17 mm Hg, and a conjunctival bleb had reformed.     

Ophthalmologic and electro-oculographic findings in Gardner's syndrome

We examined six patients with Gardner's syndrome, eight first-degree relatives, and 31 age- and sex-matched controls to document the presence, distribution, and morphologic features of congenital hypertrophy of the retinal pigment epithelium. Patients with Gardner's syndrome had multiple, bilateral lesions, with 288 of 346 foci (83%) located posterior to the equator. Linear-shaped congenital hypertrophy of the retinal pigment epithelium, a distinctive finding in these patients, accounted for 44 of 140 large lesions (31%). Despite multifocal fundus involvement, results of electro-oculography were normal in all eyes tested.     

Plasma leptin level and its relationship with body composition in hemodialysis patients

Leptin is a newly found hormone secreted by adipocytes that regulates food intake, thermogenesis, and body fat. We measured plasma leptin levels in 103 patients with chronic renal failure treated by hemodialysis and 167 age- and gender-matched healthy control subjects to examine the impact of renal failure on plasma leptin levels and the influence of leptin on body composition measured by dual-energy X-ray absorptiometry. Hemodialysis patients showed a significant decrease in both body fat mass and lean body mass compared with those of the control subjects. Plasma leptin was significantly elevated in the hemodialysis group over the controls. In both groups, leptin was higher in female than male subjects, and it correlated positively with percent body fat. The subjects were divided into six categories according to percent body fat, and plasma leptin levels were compared between the two groups in the same category. Leptin of hemodialysis patients was significantly higher than that of the control subjects in the percent body fat categories of 30 or greater, whereas there was no statistically significant difference in leptin concentrations in the lower percent body fat categories. This was also true in the comparison in each gender, and leptin levels in female subjects showed a more remarkable difference between the hemodialysis and control groups in obese categories. Multiple regression analysis in all subjects indicated that plasma leptin levels were independently affected by percent body fat, plasma insulin concentration, gender, and renal failure. The positive impact of renal failure on leptin remained significant in the subjects with percent body fat of 30 or greater in the multiple regression model, whereas it was no longer significant in the remaining lean subjects. In multiple regression analysis of factors affecting fat mass index and lean mass index, leptin level was selectively associated with fat mass index, but not with lean mass index, regardless of percent body fat ranges. These results indicate that renal failure is an important factor affecting plasma leptin levels, especially in obese female subjects, and that hyperleptinemia was closely related to fat mass but not to lean body mass in hemodialysis patients.     

An analysis of astrocytic cell lines with different abilities to promote axon growth

The adult mammalian central nervous system (CNS) lacks the capacity to support axonal regeneration. There is increasing evidence to suggest that astrocytes, the major glial population in the CNS, may possess both axon-growth promoting and axon-growth inhibitory properties and the latter may contribute to the poor regenerative capacity of the CNS. In order to examine the molecular differences between axon-growth permissive and axon-growth inhibitory astrocytes, a panel of astrocyte cell lines exhibiting a range of axon-growth promoting properties was generated and analysed. No clear correlation was found between the axon-growth promoting properties of these astrocyte cell lines with: (i) the expression of known neurite-outgrowth promoting molecules such as laminin, fibronectin andN-cadherin; (ii) the expression of known inhibitory molecules such tenascin and chondroitin sulphate proteoglycan; (iii) plasminogen activator and plasminogen activator inhibitor activity; and (iv) growth cone collapsing activity. EM studies on aggregates formed from astrocyte cell lines, however, revealed the presence of an abundance of extracellular matrix material associated with the more inhibitory astrocyte cell lines. When matrix deposited by astrocyte cell lines was assessed for axon-growth promoting activity, matrix from permissive lines was found to be a good substrate, whereas matrix from the inhibitory astrocyte lines was a poor substrate for neuritic growth. Our findings, taken together, suggest that the functional differences between the permissive and the inhibitory astrocyte cell lines reside largely with the ECM.