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Factors affecting magnetic retention of particles in the upper airways: an in vitro and ex vivo study.

This paper presents the results of experiments using an in vitro model and an ex vivo animal model (Rana catesbeiana) to study magnetic particle retention in the conducting airways, specifically the trachea and bronchi. The purpose of these experiments was to determine the significant factors for retention of magnetic particles deposited from an aerosol at the airway surface using a magnetic field. The results indicate that the apparent viscosity of the mucus layer at low shear rates is the most significant obstacle to particle retention. The results also show that particle size and aggregation play major roles in particle retention. The mucus transport rate, unlike the effect of fluid velocity in intravenous applications, did not appear to be a determining factor for particle retention. It was also found that a suitably designed magnetic system, aside from having a high intensity, needs to exert a strong radial field to promote particle aggregation. The findings suggest that one possible approach to magnetic particle retention could be delivery of a mucolytic agent along with the drug particles. This study provides the fundamentals needed for development of a targeted magnetic drug delivery system for inhaled therapeutic aerosol particles.

Administration, Inhalation↗

Mineral retention in young men consuming soy-fiber-augmented liquid-formula diets.

The effect of a nutritionally complete liquid-formula diet without soy polysaccharide or with the fiber source at 20, 30, or 40 g/d on mineral retention in young men was examined. Addition of 20 g soy polysaccharide to the liquid formula significantly (p less than 0.05) improved the retentions of copper, iron, zinc, and magnesium over the diet without added fiber. The highest level of soy polysaccharide (40 g/d) resulted in significantly (p less than 0.05) lower Cu, Zn, Fe, and Mg retentions than did the 20-g diet and the 30-g diet had an intermediate effect. Except for slightly negative Cu (-0.1 +/- 0.4 mg) and Fe (-0.6 +/- 3.7 mg) retentions on the 40-g diet, retentions of all minerals remained positive throughout this study. The liquid-formula diet supplemented with 40 g soy polysaccharide could have a deleterious effect on mineral retentions in persons consuming the diet as their sole nutritional source.

Calcium↗

Manganese retention in man: a method for estimating manganese absorption in man.

Whole-body retention of 54Mn was studied in man by measurements in a sensitive whole-body counter after intake of an extrinsically labeled infant formula. Reproducible retention figures at day 10 were observed after repeated administrations to six subjects; 2.3 +/- 1.1, 3.3 +/- 3.1, and 2.4 +/- 1.4% (means +/- SD) for three separate occasions. Interindividual variation of manganese retention after intake of the same labeled diet was, however, shown to be substantial. Retention at day 10 was 2.9 +/- 1.8% (means +/- SD) and varied from 0.6 to 9.2% when measured in 14 healthy subjects. Large interindividual variations in rate of excretion were observed. The retention measurements for days 10-30, however, could be closely fitted to a single exponential function for each individual. The results regarding intraindividual and interindividual variation in Mn retention indicate that factors influencing Mn absorption can be identified only by repeated administrations using each subject as his/her own control.

Administration, Oral↗

Pharmacological enhancement of long-term memory retention in old mice.

This study examined memory retention deficits in 24-month-old mice as compared to 4-month-old mice and if they were related to an altered functional state of neurotransmitters or hormones that modulate memory. We administered to 24-month-old C57BL/6Nnia mice pharmacological compounds known to improve retention in young mice. Eleven of the pharmacological agents improved retention in old mice at the dose previously shown to be optimal in young mice. Clonidine and ST 587, the two alpha noradrenergic agonists tested, failed to enhance retention at the optimum dose for young mice. A dose response study with clonidine found that a lower dose (1 mg/kg) improved retention in old mice rather than the optimal dose (3 mg/kg) for young mice. These data suggest that memory retention in old C57BL/6Nnia mice is similar to that of young mice, with the exception of alpha noradrenergic receptors.

Aging↗

Influence of genetic differences in feed efficiency of young chickens on derivation of metabolizable energy from the diet and nitrogen retention.

The relationship of efficiency of efficiency of feed utilization with metabolizable energy derived from the diet and nitrogen retention was studied in broiler strains and in lines selected for divergence in feed conversion ratio. Individual feed conversion (g feed/g gain) and metabolizable energy derived from the diet and nitrogen retention (determined by chromic oxide method) of these strains and lines were measured, and correlations were determined at various intervals from 4 to 9 weeks of age to determine the effects of age, sex, strain, feed conversion, growth, and feed consumption on the metabolizable energy derived from the diet and nitrogen retained. Although there were significant differences in feed conversion between sexes, strains, and lines selected for divergence in feed conversion, there were no associated differences in metabolizable energy derived from the diet or in nitrogen retention. There were no significant correlations of consumption, growth, or feed conversion with metabolizable energy derived from the diet or nitrogen retention. Nitrogen retention of the White Plymouth Rock strain was significantly higher for all ages. These results show that differences observed in growth, consumption, or feed conversion do not influence derivation of metabolizable energy from the diet or nitrogen retention.

Age Factors↗

Apparent mineral retention is similar in control and hyperinsulinemic men after consumption of high amylose cornstarch.

The effects on apparent mineral retention after long-term consumption of a high amylose diet containing 30 g resistant starch (RS) were investigated in 10 control and 14 hyperinsulinemic men. Subjects consumed products (bread, muffins, cookies, corn flakes and cheese puffs) made with standard (70% amylopectin, 30% amylose; AP) or high amylose (70% amylose, 30% amylopectin; AM) cornstarch for two 14-wk periods in a crossover pattern. Starch products replaced usual starches in the habitual diet for 10 wk followed by 4 wk of consuming the controlled diets. During wk 12, all urine, feces and duplicate foods were collected for 7 d. Urinary chromium losses after a glucose tolerance test or 24-h collections of the hyperinsulinemic and control subjects did not differ and were not altered by diet. Except for zinc, the two subject types did not differ significantly in apparent mineral balance. Apparent retentions of calcium and magnesium were not significantly affected by diet (AM vs. AP) or type-by-diet interaction. Apparent iron retention tended to be greater after AM than AP consumption (P < 0.09). Apparent copper retention was greater after consuming AP than after AM (P < 0.02), whereas apparent zinc retention was greater after consuming AM than after AP (P < 0.018). Zinc also showed a significant type-by-diet interaction (P < 0.034) with control subjects retaining less zinc after consuming AP than after AM. In summary, a high amylose cornstarch diet containing 30 g RS could be consumed long term without markedly affecting, and possibly enhancing, retention of some minerals.

Adult↗

Effects of copper source on phosphorus retention in broiler chicks and laying hens.

Copper sulfate is often added to broiler and laying hen diets at prophylactic dosages due to its antimicrobial and growth promoting effects despite reduced P digestibility, whereas P use from other Cu sources is unknown. Therefore, male broiler chicks were fed diets containing 0 or 250 ppm Cu from Cu sulfate (Cu SUL), Cu citrate (Cu CIT), Cu lysinate (Cu LYS), or CuCl from 9 to 22 d of age (8 cages/diet, 6 birds/cage) to determine the effect of each Cu source on performance characteristics, bone mineralization, and P retention. Body weight gain was not different among treatments (P > 0.05). Supplementation with 250 ppm Cu from Cu LYS resulted in chicks having greater toe and tibia ash weights as compared with chicks fed Cu SUL (P < or = 0.05) but was not significantly different from those of birds fed Cu CL, Cu CIT, and 0 ppm Cu diets. Supplementation with Cu LYS resulted in birds with greater toe ash percentage as compared with birds fed Cu CIT, Cu SUL, and the 0 ppm Cu diets (P < or = 0.05) but was not significantly different than those of birds fed the CuCl diet. Birds fed the Cu LYS diet had greater tibia ash percentage as compared with birds fed Cu SUL and 0 ppm Cu diets (P < or = 0.05) but were not significantly different than birds fed the Cu CL or Cu CIT diet. Supplementation with 250 ppm Cu SUL or Cu CIT reduced apparent P retention by 0.029 and 0.053 percentage-units of the diet, respectively (P < or = 0.05) as compared with the 0 ppm diet; whereas the apparent P retention when 250 ppm Cu LYS or Cu CL was fed was not different from the 0 ppm Cu diet (P > 0.05). Feeding of different Cu sources in a subsequent experiment had no influence on P retention in laying hens (P > 0.05). In conclusion, supplementation with 250 ppm Cu from Cu CIT or Cu SUL resulted in decreased apparent P retention. Supplementation with 250 ppm Cu CL or Cu LYS, however, improved apparent P retentions as compared with Cu CIT or Cu SUL.

Aging↗

Relationship between bicarbonate retention and bone characteristics in broiler chickens.

Determination of the bicarbonate retention factor (BRF) is an important step during development of the indicator amino acid oxidation technique for use in a new model. A series of 4-h oxidation experiments were performed to determine the BRF of broilers aged 7, 14, 21, 28, 35, and 42 d using 4 birds per age group. A priming dose of 1.2 microCi of NaH(14)CO(3), followed by eight half-hourly doses of 1 microCi of NaH(14)CO(3) were given orally to each of 4 birds per age. The percentage of (14)C dose expired by the bird at a steady state was measured. These birds, as well as 12 additional birds matched for age and BW, were killed, and femur bone mineral density was measured by quantitative computed tomography to determine the relationship between bone development and bicarbonate retention at each age. There was a correlation (r = 0.50; P < 0.05) between total cross-sectional femur bone mineral density and bicarbonate retention at each age. A prediction equation (Y = 6.95 x 10(-2)X - 3.51 x 10(-5)X(2) + 27.58; P < 0.0001, R(2) = 0.79) where Y = bicarbonate retention and X = BW was generated to predict Y as a function of X. Bicarbonate retention values peaked at 28 d, during the stage of the most rapid bone deposition and the highest growth rate. A constant BRF was found from 1,900 to 2,700 g of BW of 35.15 +/- 1.095% (mean +/- SEM). This retention factor will allow the accurate correction of oxidation of (14)C-labeled substrates in broilers of different ages and BW in future indicator amino acid oxidation studies.

Aging↗

Androgen-mediated development in male rat offspring exposed to flutamide in utero: permanence and correlation of early postnatal changes in anogenital distance and nipple retention with malformations in androgen-dependent tissues.

Male offspring exposed in utero to antiandrogens often display alterations in androgen-dependent developmental markers (e.g., anogenital distance [AGD], nipple retention) together with clearly adverse responses such as genital malformations and reproductive tract lesions. The objectives of this study were to determine whether in utero exposure to flutamide results in permanent changes in male AGD and nipple retention, characterize the dose-response relationship between flutamide-mediated alterations in these landmarks and clearly adverse antiandrogenic effects, and establish the predictive value and relationship between AGD and nipple retention, and other adverse manifestations. Male offspring were exposed in utero to 0, 6.25, 12.5, 25, or 50 mg/kg/day (po) of flutamide from gestation days 12 to 21. Offspring were uniquely identified at birth, and various androgen-mediated end points (AGD, areola/nipple retention, cryptorchidism, reproductive tract weights, and malformation incidence) were examined throughout life. In utero flutamide exposure significantly decreased the AGD on postnatal day (PND) 1 and increased areola/nipple retention in male rats on PND 13. Flutamide-induced alterations in AGD and areolae/nipples in early postnatal life correlated with a reduction in AGD and retained nipples observed in the adult. Prenatal flutamide exposure resulted in dose-responsive increases in cryptorchidism. Hypospadias were observed in all flutamide-exposed offspring. In utero flutamide exposure induced partial or complete prostate agenesis and decreased the weights of the seminal vesicles, levator ani bulbocavernosus (LABC) muscle, testes, and epididymides in a dose-dependent manner. Epididymal malformations were observed mainly in the 50 mg/kg/day flutamide dose group. In general, flutamide-induced alterations in dihydrotestosterone (DHT)- and testosterone (T)-dependent development each had similar respective dose-response curves. DHT-mediated development was more sensitive to in utero flutamide exposure than T-dependent processes. However, the dose-response curves for flutamide-induced changes in cryptorchidism and seminal vesicle weight were intermediate between the dose-response curves for DHT- and T-mediated development, indicating that proper development of these tissues may require both androgens. The LABC also displayed a dose-dependent decrease in weight that was similar to dose-response observed with seminal vesicle weight and was the most sensitive T-dependent end point measured. Flutamide-induced decreases in AGD predicted subsequent malformations as evidenced by logistic regression and receiver operator characteristic analysis of malformations versus AGD. However, the AGD that would predict a 10% incidence of seminal vesicle malformations is equivalent to a female AGD. An almost fully feminized phenotype of 10-12 nipples was observed in animals that had malformations in T-dependent tissues, whereas 6 or more nipples were observed in animals with malformation in DHT-dependent tissues. These data suggest that flutamide-mediated changes in AGD and nipple retention are not sensitive predictors of altered T-mediated development.

Anal Canal↗

The effect of stress level, amino acid formula, and nitrogen dose on nitrogen retention in traumatic and septic stress.

Eighty-seven patients were entered into a randomized, prospective, double-blind, six-center study to evaluate the effect of amino acid loading and a formula that was branched chain enriched (50%) on nitrogen retention in metabolic stress. The patients had varying levels of metabolic stress (0-3) after major surgery, polytrauma, or surgical sepsis. The study was isocaloric and isonitrogenous and lasted for 7 days. The patients received either a standard amino acid formula (SAA) (Travasol) or a 50% branched chain enriched formula that was equimolar, leucine, isoleucine, and valine (MAA) (Travasol + Branchamin concentrate) at a dose of 1.0-2.0 g/kg/day in a fixed ratio with 114 glucose calories per gram of nitrogen administered. The nitrogen retention was proportionate to the nitrogen (and, therefore, caloric) load in both groups. The MAA group, however, had better nitrogen retention, reached nitrogen equilibrium at a lower dose of amino acids, and had less urinary nitrogen excretion per gram of nitrogen administered. Since the groups were isonitrogenous and the calorie to nitrogen ratios were fixed, it appears that nitrogen equilibrium in surgical stress is proportionate to the amino acid load over a range of 0.05-0.4 g/kg/day of nitrogen; and that MAA are more efficient at inducing nitrogen retention and a reduction in urea excretion. These effects on nitrogen retention were more significant at level 2 stress or greater. At these higher stress levels, a dose of 2 +/- 0.2 g/kg/day of MAA seemed most efficient in promoting nitrogen retention.

Adult↗

Whole body retention of Tc-99m phosphate in Paget's disease of bone.

The effectiveness of the 24-hour whole body retention of Tc-99m MDP in monitoring disease activity was evaluated in 58 patients with Paget's disease of bone. Patients had baseline 24-hour retention studies, bone scans, radionuclide bone blood-flow studies, and alkaline phosphatase and OH-Proline level measurements. Increased retention of Tc-99m MDP was present in 88% (51/58) of individuals while alkaline phosphatase and OH-Proline were respectively elevated in 100% (58/58) and 64% (35/55) of patients. Forty-seven examinations were further obtained to evaluate changes in retention with therapy. Retention correctly reflected response to treatment in 89.3% of follow-ups versus 85.1% with alkaline phosphatase (n = 47). It was accurate in 90.9% of patients versus 75% for OH-Proline (n = 44). We conclude that the retention study, while not absolutely correlative with Pagetic activity, still is useful in grading the condition. It is a simple additional step that monitors the global severity of lesions localized on bone scans.

Aged↗

Skeletal 212Pb retention following 224Ra injection: extrapolation of animal data to adult humans.

Two methods of interspecies extrapolation, one based on a correlation of skeletal 212Pb/224Ra with body weight, the other based on the mechanistic relationship between skeletal 212Pb/224Ra and reciprocal bone surface-to-volume ratio, lead to the conclusion that the retention of 212Pb in the adult human skeleton is approximately complete a few days after injection. The correlation-based method gives most probable values for 212Pb/224Ra of 1.0 and 1.1 at 2 d and 7 d after injection, compared with values of 1.05 and 1.27 expected at these same times if the retention of 212Pb were complete from the time of injection and if no 212Pb were in the injection solution. The range of values corresponding to one geometric standard error on either side of the most probable value is 0.87 to 1.21 at 2 d post-injection. With the method based on the reciprocal bone surface-to-volume ratio, the best estimate of 212Pb/224Ra at 2 d after injection is 0.88, equal to the value observed in young adult beagles. An alternative interpretation of the results of this latter method leads to the conclusion that retention is complete, with 212Pb/224Ra equal to 1.0 for a 212Pb-free injection solution and 1.1 for a solution containing 212Pb in secular equilibrium with 224Ra. This work, which uses 224Ra daughter product retention data from mice, rats and dogs following 224Ra injection, provides a scientific foundation for retention assumptions made in the calculation of mean skeletal dose for adult humans. There now appear to be few uncertainties in these latter dose values, stemming from inaccurate retention assumptions; but substantial uncertainties remain in the mean skeletal dose values for juveniles and in the endosteal tissue doses regardless of age. Risk coefficients such as those in the BEIR III report that give the lifetime probability of bone tumor induction per unit mean skeletal dose may be correct for adult humans but are probably too low for juveniles due to overestimation of juvenile dose. BEIR III risk coefficients that give tumor induction probability per unit endosteal tissue dose may be substantially too small, regardless of age, due to overestimation of endosteal dose.

Adult↗

A retention-excretion model for americium in humans.

This paper discusses current information on the biological behavior of americium and describes a biokinetic model for americium in humans. Emphasis is on the time-dependent distribution and excretion of systemic americium in the adult, but potential differences with age in parameter values are addressed, and predictive models of absorption of americium to blood from the respiratory and gastrointestinal (GI) tracts are provided in an appendix. The analysis builds on the author's previous biokinetic model for plutonium in humans and recent analyses and/or models of other authors regarding the behavior of americium and related elements in humans and laboratory animals. Compared with the retention model for americium implied in ICRP Publication No. 48, the present model, as applied to adults, yields reasonably similar whole-body retention of americium at all times, much less retention in the liver after a few months, somewhat greater retention in the total skeleton after a few years, and very similar long-term integrated activities of long-lived americium isotopes on bone surfaces. Compared with a previous model of Durbin and Schmidt, the present model, as applied to adults, predicts very similar retention in the liver at all times, somewhat smaller retention in the total skeleton after a few years, and somewhat greater urinary excretion rates at all times after acute uptake to blood.

Americium↗

Job embeddedness: a theoretical foundation for developing a comprehensive nurse retention plan.

OBJECTIVE: Using a new construct, job embeddedness, from the business management literature, this study first examines its value in predicting employee retention in a healthcare setting and second, assesses whether the factors that influence the retention of nurses are systematically different from those influencing other healthcare workers. BACKGROUND: The shortage of skilled healthcare workers makes it imperative that healthcare providers develop effective recruitment and retention plans. With nursing turnover averaging more than 20% a year and competition to hire new nurses fierce, many administrators rightly question whether they should develop specialized plans to recruit and retain nurses. METHODS: A longitudinal research design was employed to assess the predictive validity of the job embeddedness concept. At time 1, surveys were mailed to a random sample of 500 employees of a community-based hospital in the Northwest region of the United States. The survey assessed personal characteristics, job satisfaction, organizational commitment, job embeddedness, job search, perceived alternatives, and intent to leave. One year later (time 2) the organization provided data regarding voluntary leavers from the hospital. RESULTS: Hospital employees returned 232 surveys, yielding a response rate of 46.4 %. The results indicate that job embeddedness predicted turnover over and beyond a combination of perceived desirability of movement measures (job satisfaction, organizational commitment) and perceived ease of movement measures (job alternatives, job search). Thus, job embeddedness assesses new and meaningful variance in turnover in excess of that predicted by the major variables included in almost all the major models of turnover. CONCLUSIONS: The findings suggest that job embeddedness is a valuable lens through which to evaluate employee retention in healthcare organizations. Further, the levers for influencing retention are substantially similar for nurses and other healthcare workers. Implications of these findings and recommendations for recruitment and retention policy development are presented.

Adult↗

Effect of calcium/phosphorus ratio on mineral retention in parenterally fed premature infants.

We hypothesized that retention of parenterally delivered calcium (Ca) and phosphorus (P) is affected by the ratio of the delivered minerals and that a 1.7:1 ratio would be optimal since this is the ratio of retention of these minerals by the fetus. Forty-one very low birth weight (VLBW) infants were randomly assigned to one of three total parenteral nutrition (TPN) solutions that were different only in their Ca:P ratios: 2:1 (76 mg/kg/day Ca and 38 mg/kg/day of P), and 1.3:1 (58 mg/kg/day Ca and 45 mg/kg/day P), and 1.3:1 (58 mg/kg/day of Ca and 45 mg/kg/day of P). Serum levels of calcium, phosphorus, and alkaline phosphatase, retentions of calcium and phosphorus and urinary cyclic AMP levels were measured after 48 h on the assigned Ca to P ratio. Calcium retentions were higher with the 2:1 and 1.7:1 ratios and phosphorus retentions were higher with the 1.3:1 and 1.7:1 ratios. The 1.7:1 ratio allowed for the highest absolute retention of both minerals and was the closest to published in utero accretion of calcium and phosphorus. The serum and urine studies demonstrated no abnormalities on any of the three ratios. Cyclic AMPs were not different among groups and were not elevated compared to previous reports suggesting that none resulted in parathyroid hormone (PTH) stimulation. We conclude that the 1.7:1 ratio is better than higher or lower ratios for delivery of calcium and phosphorus in TPN solutions at the quantities studied.

Alkaline Phosphatase↗

Calculation of renal retention function without deconvolution.

The aim of this study was to evaluate Rutland's method for the recovery of renal retention function without deconvolution. Renograms (n=5800) were generated by convolving 10 real input functions with 580 artificially created retention functions. Their ratios of minimal to mean transit time ranged from 0.1 to 1.0, and for mean transit time ranged from 3 to 60 min. The retention function was recovered from each renogram and its associated input function by calculating the first derivative of the residence time of the tracer in the kidney. Minimal, mean, and maximal transit time of the recovered retention function were calculated and compared with the original values. Qualitatively, the recovered retention function differed little from the original one. Quantitatively, values for recovered minimal transit time equalled original minimal transit time in all cases, whilst recovered mean transit time and maximal transit time equalled, respectively, the original mean transit time and maximal transit time if the original minimal to mean transit time ratio equalled 1. If this ratio was less than 1, recovered mean transit time was higher than original mean transit time and recovered maximal transit time was lower than original maximal transit time. For values of mean and maximal transit time, the differences from the original value increased with increasing original mean and maximal transit time, respectively, and with increasing renal clearance and decreasing minimal to mean transit time ratio. It is confirmed that Rutland's method is a particularly interesting alternative to deconvolution analysis. The errors that occur when recovering the retention function are relatively small.

Algorithms↗

Risk factors for retention of subretinal perfluorocarbon liquid in vitreoretinal surgery.

PURPOSE: To analyze factors that may lead to inadvertent subretinal retention of perfluorocarbon liquid (PFCL) after vitreoretinal surgery and compare surgical outcomes and complications associated with these events. DESIGN: Consecutive retrospective study. METHODS: The authors retrospectively reviewed the charts of 72 vitreoretinal surgeries using intraoperative PFCL and its removal through fluid-air exchange and subsequent tamponade. Indications for surgery included trauma, retinal detachment, giant retinal tear, and submacular hemorrhage. Most interventions studied had significant amounts of proliferative vitreoretinopathy and were required after failed or complicated previous vitreoretinal surgery. MAIN OUTCOME MEASURES: Analysis was focused on the occurrence of subretinal retention of PFCL during different surgical procedures and techniques, indications, anatomic and visual results, and complications. RESULTS: At the last follow-up, the retina was completely attached in 97% of eyes treated with PFCL after 1 or 2 vitrectomies. Subretinal PFCL was found in 8 (11.1%) eyes. There was no statistical difference in the retention rate for perfluorodecalin and perfluoro-n-octane. The factor most significantly associated with subretinal retention of PFCL was the presence and large size of a peripheral retinotomy. All cases of subretinal PFCL had a retinotomy of 120 degrees or larger. The average retinotomy size in these cases was 259 degrees . Subretinal PFCL was found in 40% of eyes with a 360 degrees retinotomy. Small and medium-sized retinal breaks were not associated with PFCL retention. Another surgical procedure that correlated significantly with subretinal PFCL was lack of saline rinse during fluid-air exchange. Only 1 of the 23 eyes that were rinsed had subretinal PFCL, although many had large retinotomies. CONCLUSION: Subretinal PFCL retention is most likely to occur in eyes with large peripheral retinotomies, especially if 360 degrees . Saline rinse seems to be useful in the prevention of subretinal PFCL. The presence of subretinal PFCL does not seem to affect visual and anatomic success when located outside the macula, at least during an intermediate period of follow-up.

Adolescent↗

The Enhancing Recovery in Coronary Heart Disease Trial (ENRICHD): strategies and techniques for enhancing retention of patients with acute myocardial infarction and depression or social isolation.

The report aims to review the literature and describe the methods used for retention of patients in a clinical study. The Enhanced Recovery in Coronary Heart Disease (ENRICHD) trial was a multicenter, randomized clinical trial designed to evaluate the effects of a psychosocial intervention on cardiovascular morbidity and mortality. A total of 2481 patients met the criteria for depression, low social support, or both after a myocardial infarction and needed to be followed. Follow-up evaluation consisted of telephone interviews 3, 9, 12, 24, 36, and 48 months after enrollment and clinic visits scheduled at 6, 18, 30, 42, and 54 months. Creative strategies used to achieve optimum retention of this complex patient population over a long follow-up period are presented. Strategies to enhance adherence throughout the course of the trial required adequate tracking of patients to ensure minimum dropout, follow-up evaluation optimized through multiple methods of contact to guarantee completeness of data collection; and development of procedures to address the needs of patients at risk for dropout. Patients in the group that completed the study participated for a mean of 28.3 months, and those lost to follow-up evaluation participated for a mean of 19 months. Retention was not substantially different by gender or minority status. The results of this project can assist investigators in planning studies that require patient follow-up evaluation, and can provide clinicians with specific strategies for maximizing retention-to-treatment recommendations. As a result of the retention strategies described in this report, 93.02% of the patients completed their study participation or died. This is a very high retention rate given the complexity of the study sample, protocol, and required duration of follow-up evaluation.

Adult↗