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Biomedical subjects

Boris Kovatchev

Publications and source records attributed to Boris Kovatchev.

17 recordsLinked to original sources

Does "stubbornness" have a role in pediatric constipation?

The objective of this study was to determine if children with constipation are more stubborn, both in general and specifically regarding toileting behaviors, than children without constipation. A secondary objective was to determine if constipated children who are more stubborn are less likely to respond to routine therapeutic interventions than less stubborn constipated children. One hundred one children aged 2 to 6 years, who were first-time presenters (never received treatment) to their primary care physician (PCP) with constipation, were compared with 84 nonconstipated control children of similar age range. Comparison measures included general stubbornness and toilet-specific stubbornness (active resistance to participating in appropriate toileting behaviors). Measures of stubbornness were generated from retrospective questionnaires, prospective toileting diaries completed by the parents, and direct experimenter observations. The constipated children were treated by their PCP for 2 months and then reassessed. Constipated children were perceived by their parents to be significantly more stubborn than control children generally and specifically in terms of toileting. Some study evidence suggested that constipated children who continued to have difficulties after 2 months of treatment by their PCPs were perceived by their parents to have significantly more general stubbornness than constipated children who responded to treatment. Parent-perceived toilet-specific stubbornness significantly improved after successful treatment of the constipation by their PCP. The finding that constipated children had more parent-perceived stubbornness than children without constipation is notable because it may play a role in the development and/or maintenance of this bowel dysfunction as well as being an obstacle in treatment compliance.

Adult↗

Manual transmission enhances attention and driving performance of ADHD adolescent males: pilot study.

OBJECTIVE: Inattention is a major contributor to driving mishaps and is especially problematic among adolescent drivers with ADHD, possibly contributing to their 2 to 4 times higher incidence of collisions. Manual transmission has been demonstrated to be associated with greater arousal. This study tests the hypotheses that manual transmission, compared to automatic transmission, would be associated with better attention and performance on a driving simulator. METHOD: Ten adolescent drivers with ADHD practice driving on the simulator in the manual and automatic mode. Employing a single-blind, cross-over design, participants drive the simulator at 19:30 and 22:30 hr for 30 min in both transmissions and rate their attention to driving. RESULTS: Subjectively, participants report being more attentive while driving in manual transmission mode. Objectively, participants drive safer in the manual transmission mode. CONCLUSION: Although in need of replication, this pilot study suggests a behavioral intervention to improve driving performance among ADHD adolescents.

Accidents, Traffic↗

Relative benefits of stimulant therapy with OROS methylphenidate versus mixed amphetamine salts extended release in improving the driving performance of adolescent drivers with attention-deficit/hyperactivity disorder.

OBJECTIVE: Automobile accidents are the leading cause of death among adolescents, and collisions are 2 to 4 times more likely to occur among adolescents with attention-deficit/hyperactivity disorder. Studies have demonstrated that stimulants improve driving performance. This study compared 2 long-acting stimulant medications during daytime and evening driving evaluations. METHODS: Adolescent drivers with attention-deficit/hyperactivity disorder were compared on a driving simulator after taking 72 mg of OROS methylphenidate, 30 mg of mixed amphetamine salts extended release, or placebo in a randomized, double-blind, placebo-controlled, crossover study design. During laboratory testing, adolescents drove a driving simulator at 5:00 pm, 8:00 pm, and 11:00 pm. Driving performance was rated by adolescents and investigators. RESULTS: The study included 35 adolescent drivers with attention-deficit/hyperactivity disorder (19 boys/16 girls). The mean age was 17.8 years. The overall Impaired Driving Score demonstrated that OROS methylphenidate led to better driving performance compared with placebo and mixed amphetamine salts extended release, whereas mixed amphetamine salts extended release demonstrated no statistical improvement over placebo. Specifically, relative to placebo, OROS methylphenidate resulted in less time driving off the road, fewer instances of speeding, less erratic speed control, more time executing left turns, and less inappropriate use of brakes. OROS methylphenidate and mixed amphetamine salts extended release worked equally well for male and female adolescents and equally as well with teenagers who have combined and inattentive subtypes of attention-deficit/hyperactivity disorder. CONCLUSIONS: This study validates the use of stimulants to improve driving performance in adolescents with attention-deficit/hyperactivity disorder. In the study, OROS methylphenidate promoted significantly improved driving performance compared with placebo and mixed amphetamine salts extended release.

Accidents, Traffic↗

Calibration of ADHD assessments across studies: a meta-analysis tool.

When analyzed separately, data from small studies provide only limited information with limited clinical generalizability, due to small sample size, differing assessments, and limited scope. In this methodological paper we outline a theoretical framework for performing meta-analysis of data obtained from disparate studies using disparate tests, based on calibration of the data from such studies and tests into a unified probability scale. We apply this method to combine the data from five studies examining the diagnostic abilities of different assessments of Attention Deficit/Hyperactivity Disorder (ADHD), including behavioral rating scales and EEG assessments. The studies enrolled a total of 111 subjects, 56 ADHD and 55 controls. Each individual study had a small sample focused on a specific age/gender group, for example 8 boys ages 6-10, and generally had insufficient power to detect statistically significant differences. No gender, or age comparisons were possible within any single study. However, when calibrated and combined, the data resulted in a clear separation between ADHD versus non-ADHD groups in males below the age of 16 (p < 0.001), males above the age of 16, (p = 0.015), females below the age of 16, (p = 0.0014), and females above the age of 16, (p = 0.0022). We conclude that if data from various studies using various tests are made comparable, the resulting combined sample size and the increased diversity of the combined sample lead to increased significance of the statistical tests and allow for cross-sectional comparisons, which are not possible within each individual study.

Adolescent↗

Treatment of childhood constipation by primary care physicians: efficacy and predictors of outcome.

OBJECTIVE: Childhood constipation accounts for 3% of visits to general pediatric clinics and as many as 30% of visits to pediatric gastroenterologists. The majority of children who experience constipation and whose caregivers seek medical care are seen by primary care physicians such as pediatricians or family physicians. Little is known about how primary care physicians treat childhood constipation or the success of their treatments. With this study, we prospectively examined which treatments primary care physicians prescribe to children who present for the first time with constipation and how effective those treatments are. METHODS: A total of 119 children who were between 2 and 7 years of age (mean: 44.1 +/- 13.6 months) and presented to 26 different primary care physicians (15 pediatricians and 11 family physicians) for the treatment of constipation for the first time participated in this study. Parents completed daily diaries of their child's bowel habits for 2 weeks before starting treatment recommended by their primary care physician and again 2 months after treatment. The prescribed treatment was identified by reviewing office records of the treating physicians. RESULTS: After 2 months of treatment, 44 (37%) of 119 children remained constipated. In the majority (87%) of cases, physicians prescribed some form of laxative or stool softener. The most commonly prescribed laxatives were magnesium hydroxide (77%), senna syrup (23%), mineral oil (8%), and lactulose (8%). In nearly all cases, a specific fixed dose of laxative was recommended; in only 5% of cases were parents instructed clearly to adjust the dose of laxative up or down to get the desired effect. In approximately half of the cases, physicians recommended some sort of dietary intervention. Some form of behavioral intervention was mentioned in the office records of approximately one third of cases; however, in most cases, little detail was provided. In 45% of cases, physicians prescribed disimpaction using oral cathartics, enemas, or suppositories followed by daily laxatives. In 35% of cases, physicians prescribed daily laxatives without any disimpaction procedure. In the remainder, physicians prescribed only dietary changes (5%), the use of intermittent laxatives (9%), or no therapy (7%). Treatment success corresponded to how aggressively the child was treated. Specifically, children who underwent some form of colonic evacuation followed by daily laxative therapy were more likely to have responded to treatment than were those who were treated less aggressively. CONCLUSION: Primary care physicians tend to undertreat childhood constipation. After 2 months of treatment, nearly 40% of constipated children remain symptomatic.

Cathartics↗

Using the internet to provide information prescriptions.

INTRODUCTION: An information prescription is the provision of specific information to a patient on how to help manage a health problem. The Internet is being used increasingly as a source for information prescriptions, with clinicians directing patients to specific Web sites. As with any health care intervention, patients' lack of compliance is a barrier to the effectiveness of Web-based information prescriptions (WebIPs). WebIPs cannot be helpful if patients do not review the information prescribed for them. OBJECTIVE: The main objective of this study was to quantify the percentage of families who visit a Web site that was specifically prescribed by their physician. In addition, the use of an e-mail reminder was used to determine if it increases the likelihood that families will visit the prescribed Web site. Finally, barriers to accessing the prescribed Web site were identified. METHODS: Children were eligible if they presented to the pediatric gastroenterology clinic with chronic constipation and/or encopresis and their family had an active e-mail account and access to the Internet in their home. During their clinic visit, physicians instructed families to visit a Web site that provided educational information pertinent to their child's problem. Families were given a form with the Web-site address and a log-in identification number. Two days after their clinic visit, half of the families received an e-mail reminding them to visit the Web site. Families were contacted 1 week after their clinic visit to identify barriers to accessing the Web site. RESULTS: Eighty-three families participated in the study. Of the 83 families, 54 (65%) visited the prescribed Web site within 1 week of their clinic visit. Families who received e-mail reminders were significantly more likely to visit the Web site than families who did not receive an e-mail reminder (77% vs 53%). This difference could not be explained by the type or speed of Internet connection or how frequently they accessed the Internet or e-mail. The most common reasons that families cited for not accessing the Web site were "I forgot" and "I didn't have time." Few families cited technical reasons for not accessing the Web site. CONCLUSIONS: Almost two thirds of the families given a WebIP logged on to the prescribed Web site. The probability that families would access the site was increased by 45% with an e-mail reminder. Clearly, e-mail prompts improve compliance to WebIPs. As content and treatment programs continue to proliferate on the Web, it is important to identify barriers and solutions to them to improve overall compliance.

Adolescent↗

Evaluating the clinical accuracy of two continuous glucose sensors using continuous glucose-error grid analysis.

OBJECTIVE: To compare the clinical accuracy of two different continuous glucose sensors (CGS) during euglycemia and hypoglycemia using continuous glucose-error grid analysis (CG-EGA). RESEARCH DESIGN AND METHODS: FreeStyle Navigator (Abbott Laboratories, Alameda, CA) and MiniMed CGMS (Medtronic, Northridge, CA) CGSs were applied to the abdomens of 16 type 1 diabetic subjects (age 42 +/- 3 years) 12 h before the initiation of the study. Each system was calibrated according to the manufacturer's recommendations. Each subject underwent a hyperinsulinemic-euglycemic clamp (blood glucose goal 110 mg/dl) for 70-210 min followed by a 1-mg.dl(-1).min(-1) controlled reduction in blood glucose toward a nadir of 40 mg/dl. Arterialized blood glucose was determined every 5 min using a Beckman Glucose Analyzer (Fullerton, CA). CGS glucose recordings were matched to the reference blood glucose with 30-s precision, and rates of glucose change were calculated for 5-min intervals. CG-EGA was used to quantify the clinical accuracy of both systems by estimating combined point and rate accuracy of each system in the euglycemic (70-180 mg/dl) and hypoglycemic (<70 mg/dl) ranges. RESULTS: A total of 1,104 data pairs were recorded in the euglycemic range and 250 data pairs in the hypoglycemic range. Overall correlation between CGS and reference glucose was similar for both systems (Navigator, r = 0.84; CGMS, r = 0.79, NS). During euglycemia, both CGS systems had similar clinical accuracy (Navigator zones A + B, 88.8%; CGMS zones A + B, 89.3%, NS). However, during hypoglycemia, the Navigator was significantly more clinically accurate than the CGMS (zones A + B = 82.4 vs. 61.6%, Navigator and CGMS, respectively, P < 0.0005). CONCLUSIONS: CG-EGA is a helpful tool for evaluating and comparing the clinical accuracy of CGS systems in different blood glucose ranges. CG-EGA provides accuracy details beyond other methods of evaluation, including correlational analysis and the original EGA.

Adult↗

Combined psychophysiological assessment of ADHD: a pilot study of Bayesian probability approach illustrated by appraisal of ADHD in female college students.

Manifestations of ADHD are observed at both psychological and physiological levels and assessed via various psychometric, EEG, and imaging tests. However, no test is 100% accurate in its assessment of ADHD. This study introduces a stochastic assessment combining psychometric tests with previously reported (Consistency Index) and newly developed (Alpha Blockade Index) EEG-based physiological markers of ADHD. The assessment utilizes classical Bayesian inference to refine after each step the probability of ADHD of each individual. In a pilot study involving six college females with ADHD and six matched controls, the assessment achieved correct classification for all ADHD and non-ADHD participants. In comparison, the classification of ADHD versus non-ADHD participants was < 85% for any one of the tests separately. The procedure significantly improved the score separation between ADHD versus non-ADHD groups. The final average probabilities for ADHD were 76% for the ADHD group and 8% for the control group. These probabilities correlated (r = .87) with the Brown ADD scale and (r = .84) with the ADHD-Symptom Inventory used for the screening of the participants. We conclude that, although each separate test was not completely accurate, a combination of several tests classified correctly all ADHD and all non-ADHD participants. The application of the proposed assessment is not limited to the specific tests used in this study--the assessment represents a general paradigm capable of accommodating a variety of ADHD tests into a single diagnostic assessment.

Adult↗

Impact of methylphenidate delivery profiles on driving performance of adolescents with attention-deficit/hyperactivity disorder: a pilot study.

OBJECTIVE: Adolescents with attention-deficit/hyperactivity disorder (ADHD) are at high risk for driving accidents. One dose of methylphenidate (MPH) improves simulator driving performances of ADHD-diagnosed adolescents at 1.5 hours post-dose. However, little is known about the effects of different MPH delivery profiles on driving performance throughout the day. METHOD: This randomized, crossover, single-blind study compared osmotic, controlled-release oral system (OROS) MPH (Concerta) given q.d. to immediate-release MPH (Ritalin) given in equal doses t.i.d. on driving performance among six male ADHD-diagnosed adolescent drivers aged 16 to 19 years. Under each treatment condition, participants were maintained on their medication dosage for 7 days, then drove a sophisticated driving simulator at 2 p.m., 5 p.m., 8 p.m., and 11 p.m. The primary outcome measure was each participant's computer-quantified Impaired Driving Score (IDS). RESULTS: IDS worsened in the evenings for participants receiving MPH t.i.d. but remained stable when they received once-daily OROS MPH. Participants performed significantly better when receiving OROS MPH q.d. compared with MPH t.i.d. (F = 9.3, df = 1, p =.004). When MPH was given t.i.d., IDS significantly worsened beginning at 8 p.m. compared to OROS MPH (p =.01). CONCLUSIONS: Participants demonstrated significantly less variability and better driving performance when receiving OROS MPH q.d. compared to MPH t.i.d., particularly in the evenings.

Adolescent↗

Hypoglycemia anticipation, awareness and treatment training (HAATT) reduces occurrence of severe hypoglycemia among adults with type 1 diabetes mellitus.

Severe hypoglycemia (SH) can be a significant problem for patients around the world with Type 1 Diabetes Mellitus (T1DM). To avoid SH, patients need to better manage, and reduce the occurrence of, preceding mild hypoglycemia. Hypoglycemia Anticipation, Awareness and Treatment Training (HAATT), developed in the United States specifically to address such issues, was evaluated at short- and long-term follow-up in a medically, economically and culturally different setting; Bulgaria. Sixty adults with T1DM and a history of recurrent SH (20 each from Sofia, Russe, and Varna, Bulgaria) were randomized to Self-Monitoring of Blood Glucose (SMBG) or SMBG+ HAATT. For 6 months before and 1 to 6 and 13 to 18 months after intervention, participants recorded occurrence of moderate, severe, and nocturnal hypoglycemia. For 1-month pre- and post-intervention, participants completed daily diaries concerning their diabetes management. Relative to SMBG, HAATT produced significant improvement in occurrence of low BG, moderate, severe, and nocturnal hypoglycemia, and detection and treatment of low BG (p values < .05 to < .001), with no compromise in metabolic control. At long-term follow-up, HAATT participants continued to have significantly fewer episodes of moderate and severe hypoglycemia. These findings suggest that a structured, specialized psycho-educational treatment program (HAATT) can be highly effective in managing hypoglycemia.

Adult↗

An Internet intervention as adjunctive therapy for pediatric encopresis.

This study evaluated the benefits of enhanced toilet training delivered through the Internet for children with encopresis. Twenty-four children with encopresis were randomly assigned to the Internet intervention group (Web) or no Internet intervention group (No-Web). All participants continued to receive routine care from their primary care physician. The Web participants demonstrated greater improvements in terms of reduced fecal soiling, increased defecation in the toilet, and increased unprompted trips to the toilet (ps<.02). Both groups demonstrated similar improvements in knowledge and toileting behaviors. Internet interventions may be an effective way of delivering sophisticated behavioral interventions to a large and dispersed population in a convenient format.

Behavior Therapy↗

Assessment of behavioral mechanisms maintaining encopresis: Virginia Encopresis-Constipation Apperception Test.

OBJECTIVE: To develop and test a scale for parent and child, evaluating theoretical and clinical parameters relevant to children with encopresis. Encopretic children were hypothesized to have more bowel-specific, but not more generic, psychological problems, as compared with nonsymptomatic control children. In addition, mothers were also believed to be more discerning than children. METHODS: The Virginia Encopresis-Constipation Apperception Test (VECAT) consists of 9 pairs of bowel-specific and 9 parallel generic drawings. Respondents selected the picture in each pair that best described them/their child. It was administered to encopretic children (N = 87), nonsymptomatic siblings (N = 27), and nonsymptomatic nonsiblings (N = 35). The mothers of all the participants also completed the VECAT. Encopretic children were retested 6 and 12 months posttreatment with Enhanced Toilet Training. RESULTS: The VECAT demonstrated good test-retest reliability and internal consistency. Encopretic children and their mothers reported more bowel-specific, but not more generic, problems. Bowel-specific scores improved significantly posttreatment only for those patients who demonstrated significant symptom improvement. Mothers were significantly more discerning than children. CONCLUSION: The VECAT is a reliable, valid, discriminating, and sensitive test. Bowel-specific problems appear to best differentiate children with and without encopresis.

Child↗

Treatment of childhood encopresis: a randomized trial comparing three treatment protocols.

OBJECTIVES: To compare short- and long-term effectiveness of three additive treatment protocols in children experiencing chronic encopresis. METHODS: Children, 6 to 15 years of age, who experienced at least weekly fecal soiling for 6 months or longer were eligible for the study. Children were randomly assigned to a group that received intensive medical therapy (IMT), a group that received intensive medical therapy plus a behavior management program called enhanced toilet training (ETT), or a group that received intensive medical therapy with enhanced toilet training and external anal sphincter electromyographic biofeedback (BF). Data concerning toileting habits were collected for 14 consecutive days before an initial visit, and at 3, 6, and 12 months after initiation of therapy. All data were collected using a computerized voice-mail system that telephoned the families each day. At 12 months, children were classified as significantly improved (reduction in soiling, P < 0.001) or cured ( 0.90, P < 0.001 in each case). Response to treatment during the first 2 weeks of therapy was highly predictive of outcome at 3, 6, and 12 months (P < 0.0001). Children in the ETT group used less laxative medication (P < 0.04) and required fewer treatment contacts (P = 0.08) than children in the IMM group. All three treatments resulted in significant increases in daily bowel movements passed in the toilet and self-initiated toileting, and resulted in decreases in average daily soiling at 3, 6, and 12 months (P < 0.05). CONCLUSIONS: Enhanced toilet training is somewhat more effective in treating childhood encopresis than either intensive medical therapy or anal sphincter biofeedback therapy. Although similar total cure rates at 1 year can be expected with these three forms of therapy, enhanced toilet training results in statistically significant decreases in the daily frequency of soiling for the greatest number of children.

Adolescent↗

Unequal autonegative feedback by GH models the sexual dimorphism in GH secretory dynamics.

Growth hormone (GH) secretion, controlled principally by a GH-releasing hormone (GHRH) and GH release-inhibiting hormone [somatostatin (SRIF)] displays vivid sexual dimorphism in many species. We hypothesized that relatively small differences within a dynamic core GH network driven by regulatory interactions among GH, GHRH, and SRIF explain the gender contrast. To investigate this notion, we implemented a minimal biomathematical model based on two coupled oscillators: time-delayed reciprocal interactions between GH and GHRH, which endow high-frequency (40-60 min) GH oscillations, and time-lagged bidirectional GH-SRIF interactions, which mediate low-frequency (occurring every 3.3 h) GH volleys. We show that this basic formulation, sufficient to explain GH dynamics in the male rat [Farhy LS, Straume M, Johnson ML, Kovatchev BP, and Veldhuis JD. Am J Physiol Regulatory Integrative Comp Physiol 281: R38-R51, 2001], emulates the female pattern of GH release, if autofeedback of GH on SRIF is relaxed. Relief of GH-stimulated SRIF release damps the slower volleylike oscillator, allowing emergence of the underlying high-frequency oscillations that are sustained by the GH-GHRH interactions. Concurrently, increasing variability of basal somatostatin outflow introduces quantifiable, sex-specific disorderliness of the release process typical of female GH dynamics. Accordingly, modulation of GH autofeedback on SRIF within the interactive GH-GHRH-SRIF ensemble and heightened basal SRIF variability are sufficient to transform the well-ordered, 3.3-h-interval, multiphasic, volleylike male GH pattern into a femalelike profile with irregular pulses of higher frequency.

Animals↗

The effects of glucose fluctuation on cognitive function and QOL: the functional costs of hypoglycaemia and hyperglycaemia among adults with type 1 or type 2 diabetes.

It is traditionally believed that while acute hypoglycaemia has detectable negative consequences, such as unpleasant symptoms and cognitive-motor disruptions, acute hyperglycaemia is not associated with such consequences. However, recent research with adults affected by either type 1 or 2 diabetes mellitus demonstrates that relatively mild hyperglycaemia is associated with unpleasant symptoms and cognitive disruptions. Both hyperglycaemia and hypoglycaemia can be associated with patient experiences of physical, affective, and cognitive symptoms, as well as cognitive-motor disruptions. These effects can lead to impaired functioning and quality of life. Because these effects are different across patients, their significance can be difficult to appreciate. There is ample evidence that acute hypoglycaemia is a problem for both adults with type 1 and those with type 2 diabetes, and that mild and moderate hypoglycaemia reduce one's mental efficiency relative to euglycaemic performance. There is growing evidence that transient hyperglycaemia has similar negative effects. At relatively mild levels of extreme blood glucose--either hypoglycaemia or hyperglycaemia--cognitive efficiency may decay by a third. The impact of this effect will depend on the task the patient is dealing with at the time. If the person is engaging in a relatively dangerous task, such as driving a vehicle, significant consequences could follow. Both hypoglycaemia and hyperglycaemia have been demonstrated to have not only acute, but also chronic effects in patients with type 1 as well as those with type 2 diabetes. Although hypoglycaemia occurs at a lower rate among patients with type 2 diabetes than among those with type 1, the number of patients with type 2 diabetes is so large that even this low rate results in many persons being affected.

Acute Disease↗

Controlled-release methylphenidate improves attention during on-road driving by adolescents with attention-deficit/hyperactivity disorder.

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is associated with a 3- to 4-fold increase in both driving-related accidents and associated injuries. Methylphenidate (MPH) is the most commonly prescribed psychostimulant medication for ADHD. It has been demonstrated to improve performance on a driving simulator. This study investigated whether a once-daily, long-acting, osmotic, controlled-release MPH formulation improves the driving performance of ADHD adolescents while driving their own car on an actual road segment. METHODS: Twelve ADHD-diagnosed male adolescent drivers (mean age, 17.8 years) prescribed a standard dose of 1.0 mg/kg (if they were not already taking methylphenidate) of controlled-release MPH participated in this repeated-measures crossover study. On 2 separate occasions (off/on medication randomized), participants drove a standard 16-mile road course incorporating rural, highway, and urban streets. A rater, blind to medication conditions, sat in the back seat and rated impulsive (eg, "cutting off" another driver) and inattentive (eg, drove past designated turn) driving errors. RESULTS: Impulsive driving errors were observed to occur rarely under both medication and no medication conditions. Inattentive driving errors were more common and were significantly reduced while the subject was on medication (4.6 versus 7.8; P <.01). The improvement in driving performance (change in number of errors recorded) from first to second testing was positively correlated with medication dosage (r = 0.60; P <.01). CONCLUSIONS: Once-daily controlled-release MPH improves real-life driving performance of adolescent males diagnosed with ADHD. In particular, it significantly reduces driving errors arising from inattention.

Adolescent↗