Few Adverse Events Linked to Vaccines, IOM Panel Says

From Medscape Medical News Robert Lowes August 25, 2011 — Only a small number of adverse events are caused by or clearly linked to a group of 8 vaccines, and scientific evidence favors rejecting a causal relationship between the vaccine for measles, mumps, and rubella (MMR) and autism, according to a report issued today by an expert committee of the Institute of Medicine (IOM). "The findings should be reassuring to parents that few health problems are clearly connected to immunizations, and these effects occur relatively rarely," said committee chair Ellen Wright Clayton, MD, JD, a professor of pediatrics and law at Vanderbilt University in Nashville, Tennessee, in a press release. "And repeated study has made clear that some health problems are not caused by vaccines." Analyzing more than 1000 research articles, the IOM committee weighed epidemiological, clinical, and biological evidence for adverse events associated with the 8 vaccines. In addition to the MMR vaccine, the vaccines examined are the varicella zoster vaccine, influenza vaccines (other than the 2009 H1N1 influenza vaccine), hepatitis B vaccine, human papillomavirus (HPV) vaccine, tetanus toxoid-containing vaccines other than those containing the whole-cell pertussis component, hepatitis A vaccine, and meningococcal vaccines. All 8 vaccines are covered by the National Vaccine Injury Compensation Program, and the IOM expects that the committee findings will provide the program with scientific guidance as it adjudicates injury claims. The committee reached 158 conclusions about a cause-and-effect relationship between each of the vaccines and a plethora of adverse events. In the vast majority of cases, the group decided that the evidence is inadequate to accept or reject a causal relationship. No one should construe such a determination to mean that a vaccine is either safe or unsafe, according to the committee, which noted that it never intended to make judgments on vaccine safety per se. "Policy determining vaccine use requires a balancing of risks and benefits," the report stated. "That is outside the bounds of this committee's assignment." MMR Vaccine/Autism Review Included Retracted Article by Andrew Wakefield Three other sets of conclusions about causality offer more guidance. The group decided that the evidence "convincingly" supports a link between anaphylaxis and MMR, varicella, influenza, hepatitis B, meningococcal, and tetanus toxoid vaccines; febrile seizures and MMR vaccine (such seizures almost always have no long-term consequences); syncope and the injection of any vaccine; deltoid bursitis and the injection of any vaccine; disseminated Oka-strain varicella zoster virus, along with Oka-strain varicella zoster virus viral reactivation (both with and without other organ involvement) and varicella vaccine; and measles inclusion body encephalitis and MMR vaccine in individuals with severe immune system deficiencies. According to another set of committee conclusions with a lower certainty level, scientific evidence favors accepting a causal relationship between anaphylaxis and HPV vaccine, transient arthralgia in adult women and MMR vaccine, transient arthralgia in children and MMR vaccine, and a mild and temporary oculorespiratory syndrome and certain trivalent influenza vaccines in Canada. Conversely, the committee stated that the evidence favors rejecting a causal relationship between type 1 diabetes and MMR vaccine; type 1 diabetes and diphtheria, tetanus, and pertussis vaccine; Bell's palsy and inactivated influenza vaccine; asthma exacerbation or reactive airway disease episodes and inactivated influenza vaccine; and autism and MMR vaccine. In its deliberation on MMR vaccine and autism, the committee stated that it reviewed 22 studies for epidemiologic evidence but relied only on 5 that, unlike the others, were "reasonably valid" overall. Each of the 5 studies asserted that there is no causal relationship between the vaccine and autism. The committee also reviewed 4 articles and weighed evidence for the biological mechanisms by which MMR vaccine could possibly trigger autism. Its report noted that one of those articles, authored by the controversial Andrew Wakefield, was retracted last year by its publisher, The Lancet. Earlier this year, a series of articles and editorials in the British Medical Journal called Wakefield's article an "elaborate fraud." "The committee assesses the mechanistic evidence regarding an association between MMR vaccine and autism as lacking," the report stated.

Steroids May Alleviate Acute Pyelonephritis in Children

From Medscape Medical News Laurie Barclay, MD August 22, 2011 — Adjunctive treatment with oral methylprednisolone may lower the occurrence and/or severity of renal scarring in children hospitalized for acute pyelonephritis, according to the results of a randomized controlled trial reported online in the August 15 issue of Pediatrics. "Renal scarring after acute pyelonephritis is associated with long-term sequelae," write Ya-Yun Huang, MD, from the Department of Pediatrics, National Cheng Kung University Medical College and Hospital in Tainan, Taiwan, and colleagues. "Preventing scarring after acute pyelonephritis depends not only on early diagnosis and rapid treatment to eradicate the bacteria but also ameliorating the destructive inflammatory response." The goal of the study was to examine whether glucocorticoids could prevent formation of renal scars after a first episode of acute pyelonephritis in pediatric patients younger than 16 years at high risk for renal scar formation. Inclusion criteria were an inflammatory volume of at least 4.6 mL on technetium-99m–labeled dimercaptosuccinic acid scan (DMSA) or abnormal renal ultrasonography findings. A total of 84 participants were enrolled and were randomly selected to receive either antibiotics plus methylprednisolone sodium phosphate (1.6 mg/kg/day; n = 19) or antibiotics plus placebo (n = 65) every 6 hours for 3 days. The main study endpoint was renal scarring seen on DMSA performed 6 months after treatment. At baseline, both groups had similar patient characteristics, acute inflammatory parameters, and DMSA findings. At 6 months after treatment, 33.3% of children who received methylprednisolone had renal scarring on DMSA, as did 60.0% of those who received placebo (P < .05), with median cortical defect volumes of 0.0 mL (range, 0 - 4.5 mL) and 1.5 mL (range, 0 - 14.8 mL), respectively (P < .01). Compared with the placebo group, patients in the methylprednisolone group also had faster defervescence after treatment. "Adjunctive oral [methylprednisolone] therapy reduced the occurrence and/or severity of renal scarring after acute pyelonephritis in these hospitalized children who had a high risk of renal scar formation," the study authors write. Limitations of this study include setting in a single tertiary referral center with a pioneer and small-scale design, small numbers of patients in some of the subgroup analyses, and inconsistency of the method used to identify patients at high risk for renal scarring. "Nevertheless, the results are promising, and additional studies with larger populations should be designed to validate these effects and determine the optimum dosage of [glucocorticoids] and the age of patients most likely to benefit from them," the study authors conclude. "Adjunctive oral [methylprednisolone] with adequate antibiotics merits further consideration as a potential treatment regimen to alleviate permanent tissue injury in admitted children with serious [acute pyelonephritis]." The National Cheng Kung University Hospital (Tainan) and the National Science Council (Taipei, Taiwan) supported this study. The study authors have disclosed no relevant financial relationships. Pediatrics. Published online August 15, 2011.

Exercise & Prevention of HTN in Children & Adolescents

Obesity, Salt, Exercise and Blood Pressure in Children : Exercise & Prevention of HTN in Children & Adolescents http://www.medscape.com/viewarticle/746947_5 Regular physical activity reduces the risk of cardiovascular disease morbidity and mortality, but also lowers BP and prevents the development of HTN. In a population-based prospective cohort study over an 11-year follow-up period, the incidence of HTN was reduced by 28% in men and 35% in women who engaged in high levels of physical activity. An immediate reduction in BP occurs after an aerobic exercise session (postexcercise hypotension). Several studies using ABPM demonstrated that the BP-lowering effects of exercise are most pronounced in people with HTN who engage in endurance exercise, with 24-h daytime BP decreasing by 5–7 mmHg after an isolated exercise session (acute) or following aerobic exercise training (chronic). BP remains lower for the rest of 24-h period after each 30-min period of moderate exercise (50% of maximal O2 uptake) with greater BP reductions for vigorous exercise (75% of maximal O2 uptake). The mechanisms involved in the postexercise hypotension may involve the reduced activity of sympathetic nervous and renin–angiotensin–aldosterone systems. Brownley et al. reported that 65% of the postexercise mean BP response difference could be accounted for by changes in sympathetic factors, with change in norepinephrine and pre-ejection period elongation being the single best predictors. Restoration of balance in functions of the autonomic nervous system was proposed to serve as a possible exercise-dependent mechanism of BP reduction in obese children.Moderate-intensity aerobic exercise has also been shown to augment endothelium-dependent vasodilation in humans through the increased production of nitric oxide. Data from a subset of the 1998–2002 NHANES survey, including 3110 healthy adolescents (aged 12–19 years) and 2205 adults (aged 20–49 years), revealed that cardiorespiratory fitness, estimated by the duration of a maximal treadmill exercise test, was inversely associated with the risk of developing HTN in both adolescents and adults. Low fitness was identified in 33.6% of adolescents and 13.9% of adults. Lobelo et al. also found an excess cluster of cardiovascular risk factors including SBP in both overweight and normal weight adolescents with lowest quintile of cardiovascular fitness distribution. SBP measured during exercise at the age of 9 years predicted resting SBP 6 years later in adolescent in healthy Danish children. Decline in duration and intensity of physical activity was associated with higher SBP in 12-year-old adolescents followed longitudinally for 5 years. A decline of one session of moderate to vigorous exercise session per week each year of age was reported to result in 0.40 and 0.18 mmHg higher SBP in boys and girls, respectively, at the end of the follow-up period. Intervention studies showed that aerobic exercise training at an intensity of 70–80% of maximal fitness, 5 days per week, reduced SBP in hypertensive and obese adolescents. However, a meta-analysis of 12 randomized controlled trials by Kelley et al. reported that exercise led to small, but not statistically significant, reductions in resting BP in children and adolescents. The lack of statistical significance was attributed to the fact that the majority of the subjects were normotensive, as well as to the lack of strictly defined sedentary control group in most of the included studies. More recent data provide increasing evidence for the positive influence of regular aerobic exercise in resting and 24-h SBP in obese and hypertensive children and adolescents.Apart from the positive effects on BP and HTN rate, Meyer et al. demonstrated that regular exercise, three-times per week, 60–90 min per day, over 6 months, improved early vascular changes as measured by flow-mediated dilation and carotid intima-media thickness. In a similar study by Maggio et al. the beneficial effects on BP, BMI and arterial stiffness remained 2 years after the cessation of training in obese children, in a recently published follow-up study.The majority of the subjects maintained physical activity with further improvements of BP and arterial function. Dietary supervision should be combined with regular physical activity, aiming to control BP, reduce extra weight, improve insulin sensitivity and establish a new lifestyle for children prone to developing HTN and cardiovascular disease. Children of parents with relatively high physical activity have been reported to be 5.8-times more likely to be active themselves than children of two inactive parents The main correlates of physical activity in a group of Singaporean adolescents were self-efficacy, enjoyment of physical activity, parental support and participation in sport teams. Current recommendations for exercise in healthy children and adolescents include 30–60 min per day of moderate-to-vigorous physical activity at least three-times per week.Moderate-to-vigorous-intensity exercise equals to 5–8 metabolic equivalents. This intensity should be maintained for a long duration of time to lower BP values in children with mild essential HTN (five-times per week for 30–60 min). Ideal levels of physical activity should be calculated for each individual separately, in connection with the expected cardiovascular benefit from a greater oxygen consumption. Moreover, children should be encouraged to reduce time spent in sedentary activities, such as playing video games or watching television to less than 2 h per day.

Obesity, Salt, Exercise and Blood Pressure in Children : Dietary Salt Intake & BP in Childhood

Stella Stabouli†1,2, Sofia Papakatsika2, and Vasilios Kotsis2 http://www.medscape.com/viewarticle/746947_4 Dietary Salt Intake & BP in Childhood The International Study of Salt and Blood Pressure (INTERSALT) has provided strong evidence for the association between dietary sodium and elevated BP in adults, especially in Western societies. Yanomamo Indians in the Amazon, who have a low-salt intake, present with a low average BP, no HTN and no positive slope of BP with age. There is also substantial evidence that a reduction in salt intake lowers BP and can prevent HTN and adverse cardiovascular outcomes. Most studies in children show that the average daily salt intake exceeds nutritional needs. As dietary habits create nutritional patterns for the young population, contamination of foods rich in salt increases over time in modern societies, emerging the need for prevention strategies that will reduce sodium exposure in the young through dietary modification. The effect of salt intake may begin early in life. A randomized trial, conducted among 476 Dutch newborn infants, studied the effect of low or normal sodium diets on BP. Infants fed with a low sodium diet had 2.1 mmHg lower SBP than those under a normal sodium diet at the age of 6 months. A subset of these populations was re-examined 15 years later. SBP and DBP at adolescence were 3.6 and 2.2 mmHg lower, respectively, in subjects assigned to the low sodium compared with the control group. Most observational epidemiological studies on salt and BP in children showed a significant positive association between dietary sodium and BP. However, in a study among Spanish school children, urinary excretion of sodium did not correlate with BP, whereas bodyweight correlated directly with BP and salt intake. The investigators assumed that the BP-raising effect of increased dietary sodium might not be seen until a certain age. Moreover, Howe et al. reported that dietary short-term sodium interventions, consisting of a 4-week high-salt diet following 4 weeks low-salt administration, had no significant alterations on BP levels in adolescents. A more reliable estimation of the sodium effects on BP could possibly be seen after a longer time period of sodium restriction. Sinaiko et al. enrolled 13-year-old adolescents in a study of 3-year period sodium interventions. Adolescent girls receiving a low-salt diet, presented a decrease in urinary sodium excretion and a slight decrease in BP levels. A recent meta-analysis of 13 controlled trials on salt reduction in children demonstrated that even a modest reduction in sodium intake causes immediate decreases in BP, and suggested that it may well lessen the subsequent rise in BP with age. The changes in salt intake were assessed by 24-h urinary sodium in four trials, overnight urinary sodium in three trials, spot urinary sodium/creatinine ratio in two trials, spot urinary sodium in two trials, food diary in one trial and random 24-h urinary sodium in one trial. Among the 13 trials, ten were in children and adolescents and three were in infants. The median reduction in salt intake was 42% (interquartile range: 7–58%) in children and adolescents and 54% (interquartile range: 51–79%) in infants. Individual variations in response to high or low sodium intake impact on BP define salt sensitivity or resistance. Children genetically predisposed to develop HTN, such as African–Americans, as well as those with a family history of HTN, more likely exhibit increased salt sensitivity. Simonetti et al. described the highest prevalence of salt sensitivity in children with intrauterine fetal growth retardation, born small for gestational age. In this study, salt sensitivity was defined if mean 24-h BP increased by 3 mmHg on a high-salt diet and was present in 37% of the low birthweight children. Kidney volume and length measured by ultrasound were reduced in low birthweight children and correlated with increased salt sensitivity, suggesting that a deficit of the normal nephron function in children with low birthweight, may lead to increased salt sensitivity and HTN. A similar relation of birthweight to salt sensitivity has been reported in adults. Several investigators examined the impact of salt sensitivity on the circadian variation of BP. Nondipping status, which is considered an early predictor of cardiovascular and renal complications, has been associated with increased salt sensitivity in hypertensive adults. It is assumed that in individuals with high-salt sensitivity, sodium retention and diminished excretory capability leads to elevation in nighttime BP values. This nocturnal HTN compensates for diminished natriuresis during the daytime and enhances pressure natriuresis during the night. Studies with regard to nondipping pattern and salt sensitivity in children and adolescents are controversial. Salt sensitivity has been associated with nondipping status in salt sensitive normotensive black adolescents. However, in a study conducted by Simonetti et al. normotensive children and young adults maintained normal nocturnal BP dipping independently of salt intake and sensitivity.In the same study, a steeper downward slope of BP from daytime to nighttime was observed in salt-sensitive as compared with salt-resistant children and in both groups of adults. The findings of this study may show that a time interval is needed for blunted dipping to develop, as in children the excretory sodium capacity seemed less affected than in young adults with longer exposure to salt. Salt sensitivity has been reported to involve endogenous ouabain, a modulator of the sodium pump in humans. In prehypertensive and hypertensive individuals, circulating levels of endogenous ouabain are not properly regulated in relation to sodium balance. The main mechanism of endogenous ouabain action, which has been described in animal models, may be an elevation in total peripheral resistance.In normotensive rats, acute elevations in salt intake lead to impairment of the muscular arteriolar response to vasodilator agonists in 3 days.The same effect was reported in normotensive and in reduced renal mass hypertensive rats receiving a high-salt diet for 4 weeks. In normotensive rats, impairment of the vascular function was proportionate to the remodeling of the microvessel wall, so that the sodium sensitivity remained unchanged. In reduced renal mass hypertensive rats the effects on the structure of microvessels was greater and resulted in increased sodium sensitivity and HTN. Despite the major role that sodium plays in the development of HTN in children and adolescents, salt sensitivity should be characterized as one component of the whole spectrum of cardiovascular risk factors. Sensitivity to sodium or high-salt intake alone may not directly cause a hypertensive profile, but could be interrelated to other factors, such as family history of HTN, race and obesity, which altogether contribute to the development of HTN and an adverse cardiovascular profile

Risks and Benefits of Second-Generation Rotavirus Vaccines

From Medscape Pediatrics > Viewpoints William T. Basco, Jr., MD Posted: 08/17/2011 Intussusception Risk and Health Benefits of Rotavirus Vaccination in Mexico and Brazil Patel MM, López-Collada VR, Bulhöes MM, et al N Engl J Med. 2011;364:2283-2292 Study Summary The 1999 rotavirus vaccine was associated with an increased risk for intussusceptions, with the highest risk at 3-7 days after the first dose, believed to be associated with the peak viral replication occurring during this period. This resulted in 1 case of vaccine-induced intussusception per 10,000 children who received the vaccine. Studies of the 2 new rotavirus preparations, conducted in more than 120,000 children, do not reveal an increased risk for intussusception. In 2006 and 2007, Brazil and Mexico began administering the new rotavirus vaccines, allowing for an extensive postmarketing evaluation of the potential effects of these new vaccines. Patel and colleagues used 2 statistical approaches to evaluate the data: a case-series approach (resulting in a rate ratio) and a case-control approach (resulting in an odds ratio). Data were collected from 2008 to 2010 in multiple locations in both countries. In general, children were immunized at 2 months (dose 1) and 4 months (dose 2) of age. Surveillance identified potential cases, and then investigators conducted reviews of medical records to verify and obtain additional clinical data. A verified case was any infant who had intussusception documented at surgery, by contrast enema, by ultrasound, or at autopsy. All cases were between 6 and 35 weeks old at the time of intussusception and all affected children were born after the new rotavirus vaccines were introduced into their respective countries. The investigators considered the period of 1-7 days after vaccination to be the time of principal risk. They adjusted for the background incidence of intussusception in each country in 2-week intervals. They also conducted a comparison of benefit and risk and estimated how many deaths might have occurred in each country without the rotavirus vaccine. They then compared this with the number of intussusceptions and deaths from intussusceptions. The study cohort included 615 case infants (with intussusception) and 2050 control infants (without intussusception). In the intussusception group, 19 children (3.1%) died. In Mexico, 91% of infants with intussusception were diagnosed after the first dose, compared with 44% in Brazil. In Mexican infants, a significant increase in intussusception occurred in the 1- to 7-day period after the first vaccination. In Brazil, a significant increase in intussusception occurred in the 1- to 7-day period after the second vaccination. Age of receipt of the first dose of vaccine did not appear to be related to rate of intussusception in either country. The investigators comment that in Brazil, the first dose of rotavirus vaccine is given along with oral polio vaccine, whereas in Mexico, the rotavirus vaccine is given with the inactivated polio vaccine. Other existing data suggest that coadministration of these 2 live virus vaccines reduces immune response to the first rotavirus vaccine. When applied to a hypothetical cohort of children in Mexico or Brazil, the rotavirus vaccine would avert 663 rotavirus deaths in Mexico and 640 rotavirus deaths in Brazil, compared with an estimated 2 deaths in Mexico and 3 deaths in Brazil caused by the vaccine-induced intussusception. Patel and colleagues concluded that receipt of rotavirus vaccine is associated with a short-term increase in risk for intussusception, but the overall risk-benefit ratio suggests that the benefits of reduced rotavirus deaths and hospitalization in the first 5 years of life far exceed the small number of excess deaths potentially caused by the vaccine. Viewpoint In an accompanying editorial, Greenberg points out that the rotavirus vaccine has reduced hospitalization and deaths in both developed nations and in nations in transition. Clearly, some increased risk for intussusception after vaccination exists with the newer vaccines, although this risk was not demonstrated in the US trials. Whether this risk is the same in fully developed nations as in developing nations is also difficult to determine and cannot be answered directly with these data. I am most interested in the modeling part of the study, which might be the most helpful data for clinicians in the United States. The assumptions would be different if the same study were conducted in the United States, and the findings would probably be biased toward a reduced benefit of the vaccine compared with that demonstrated in Mexico and Brazil. Nonetheless, with such huge benefit-risk ratio (eg, 663 deaths averted compared with 2 vaccine-associated deaths in Mexico), the risk-benefit ratio in the United States would still be great even if the benefit was halved. References

Visual Problems in Infancy After the NICU

From CHOP Expert Commentary Monte D. Mills, MD Posted: 08/15/2011 Hi, I'm Monte Mills. I'm the Director of Ophthalmology at the Children's Hospital of Philadelphia (CHOP). I'd like to talk about eye and vision problems in babies after they've been discharged from the neonatal intensive care unit (NICU) for prematurity. This is a very relevant problem. Eye and vision problems are common in the former preemie following discharge from the NICU. We know that you, as primary care providers, provide most of the care for these children as they get older and have been discharged from the hospital. Early recognition of these problems can make a difference in long-term outcome. How common are these problems in former premature infants? They're quite common. Approximately 50% of kids will need glasses due to strabismus, amblyopia, or other vision problems after they're discharged from the NICU, even after their retinopathy of prematurity (ROP) has been taken care of. The risk of having problems is related not only to the severity of their ROP, but also to their degree of prematurity. Infants who weight less than 1500 g at birth or are less than 32 weeks' gestational age at birth have the highest risk for eye problems later in life. Ocular abnormalities caused by ROP or CNS injury from prematurity are also highly associated with cerebral palsy and other manifestations of CNS injury. One of the principles of looking at these kids is that their visual development has to be compared with that of children at their same post-conceptual age. That is, their age should be adjusted for the degree of prematurity and not their actual postnatal age. These infants need to be observed for eye and vision problems even after their retinas have become mature and they have either been treated for ROP or their retinas have matured without treatment, and they've been discharged for close follow-up from the pediatric ophthalmology service that has provided their care in the NICU. What examinations do you perform in the office? There are 4 components of office primary care screening for eyes and vision. First, look at the ocular structures and external eye examination. Second, test for visual fixation and visual development. Third, eye alignment and eye movements. Finally, the ophthalmoscopic examination. First, the eye appearance and structures would be just the observations. Are the eyelids opening and closing normally? Do the corneas and visible external and internal surfaces of the eyes appear to be normal? If not, referral needs to be made. Second, visual fixation. The best tool for visual fixation is the examiner's face. Does the child fixate and follow on the face of the mother or the face of the examiner? Horizontal following and fixation occurs earliest and subsequently vertical following. By 2-3 months of adjusted age, the child should have good horizontal fixation and following. Third, eye alignment. Do the eyes align well? Is there nystagmus or rhythmic eye movement? We know that this is very common early on, but if the child is past 3-4 months adjusted age, the child should be referred. Finally, how does the pupil and red reflex look with the ophthalmoscope? Is there a good red reflex, is it symmetric and bright in both eyes? If not, if there's a shadow or an abnormality, the patient should be referred. Look for other common problems in infancy such as tearing disorders, obstruction of a nasal lacrimal duct, or capillary hemangiomas. They may not be specifically related to prematurity, but may occur frequently in these kids. Refer these children appropriately. An early referral and early treatment for amblyopia, strabismus, and refractive errors can result in better outcomes in our infants. Thank you.

ADHD Rates Continue to Rise in the United States

From Medscape Medical News > Psychiatry Megan Brooks August 22, 2011 — Rates of attention-deficit/hyperactivity disorder (ADHD) in US children continue to trend upward, report health officials from the Centers for Disease Control and Prevention's National Center for Health Statistics. According to Lara J. Akinbami, MD, and colleagues, the percentage of American children diagnosed as having ADHD increased from 6.9% in 1998-2000 to 9.0% in 2007 to 2009. From 1998 through 2009, ADHD prevalence was higher among boys than girls. For boys, ADHD prevalence increased from 9.9% in 1998-2000 to 12.3% in 2007-2009 and for girls from 3.6% to 5.5% during the same period. ADHD prevalence varied by race and ethnicity, but differences between most groups narrowed from 1998 through 2009, the study authors note. For non-Hispanic white children, ADHD prevalence increased from 8.2% in 1998-2000 to 10.6% in 2007-2009 and from 5.1% to 9.5% for non-Hispanic black children. Mexican children had consistently lower ADHD prevalence than other racial or ethnic groups. From 1998 through 2009, ADHD prevalence increased to roughly 10% among children with family income less than 100% of the poverty level and to 11% for those with family income between 100% and 199% of the poverty level. The report also shows regional differences in ADHD prevalence. In the Midwest, ADHD prevalence rose from 7.1% in 1998-2000 to 10.2% in 2007-2009. In the South, rates rose from 8.1% to 10.3% for the 2 periods. In 1998-2000, ADHD prevalence was higher in the South region than in all other regions. In 2007-2009, ADHD prevalence was similar in the South and Midwest regions; prevalence in these 2 regions was higher than in the Northeast and West regions, the report indicates. Dr. Akinbami and colleagues note that these prevalence estimates "are based on parental report of the child ever receiving a diagnosis and thus may be affected by the accuracy of parental memory (including recall bias), by differential access to healthcare between groups (diagnostic bias), or by willingness to report an ADHD diagnosis." They also point out that it was not possible to discern whether rising prevalence of ADHD "indicates a true change in prevalence or increased detection and diagnosis of ADHD." Nevertheless, the societal costs of ADHD — including those associated with medical, educational, and criminal justice resources — are large, they write. ADHD is one of the most common mental health disorders of childhood. Hallmark symptoms, including difficulty staying focused and controlling behavior, begin in childhood and often persist into adulthood, leading to functional impairment in academic, family, and social settings. The causes and risk factors are unknown, but genetic factors likely play a role. National Center for Health Statistics Brief. 2011:70. Text