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Biomedical subjects

Ann Johnson

Publications and source records attributed to Ann Johnson.

At least 19 recordsLinked to original sources
PubMed2007

Trends in cerebral palsy among infants of very low birthweight (<1500 g) or born prematurely (<32 weeks) in 16 European centres: a database study.

BACKGROUND: The risk of cerebral palsy, the commonest physical disability of children in western Europe, is higher in infants of very low birthweight (VLBW)--those born weighing less than 1500 g--and those from multiple pregnancies than in infants of normal birthweight. An increasing proportion of infants from both of these groups survive into childhood. This paper describes changes in the frequency and distribution of cerebral palsy by sex and neurological subtype in infants with a birthweight below 1000 g and 1000-1499 g in the period 1980-96. METHODS: A group of 16 European centres, Surveillance of Cerebral Palsy in Europe, agreed a standard definition of cerebral palsy and inclusion and exclusion criteria. Data for children with cerebral palsy born in the years 1980-96 were pooled. The data were analysed to describe the distribution and prevalence of cerebral palsy in VLBW infants. Prevalence trends were expressed as both per 1000 livebirths and per 1000 neonatal survivors. FINDINGS: There were 1575 VLBW infants born with cerebral palsy; 414 (26%) were of birthweight less than 1000 g and 317 (20%) were from multiple pregnancies. 1426 (94%) had spastic cerebral palsy, which was unilateral (hemiplegic) in 336 (24%). The birth prevalence fell from 60.6 (99%CI 37.8-91.4) per 1000 liveborn VLBW infants in 1980 to 39.5 (28.6-53.0) per 1000 VLBW infants in 1996. This decline was related to a reduction in the frequency of bilateral spastic cerebral palsy among infants of birthweight 1000-1499 g. The frequency of cerebral palsy was higher in male than female babies in the group of birthweight 1000-1499 g (61.0 [53.8-68..2] vs 49.5 [42.8-56.2] per 1000 livebirths; p=0.0025) but not in the group of birthweight below 1000 g. INTERPRETATION: These data from a large population base provide evidence that the prevalence of cerebral palsy in children of birthweight less than 1500 g has fallen, which has important implications for parents, health services, and society.

Birth Weight↗
PubMed2005

Progressive loss of renal function is an age-dependent heritable trait in type 1 autosomal dominant polycystic kidney disease.

Significant intrafamilial phenotypic variability is well documented in autosomal dominant polycystic kidney disease (ADPKD) and suggests a modifier effect. In this study, variance components analysis was performed to estimate the contribution of genetic factors for within-family renal disease variability in 406 patients from 66 type 1 ADPKD families. Overall, 39% of the study patients had ESRD at their last follow-up, and their renal survival did not differ by gender (P = 0.35, log-rank test). Because their frequency plot of creatinine clearance (Ccr) assumed a bimodal distribution with a marked kurtosis that was not improved by transformations, the study cohort was decomposed into two separate groups (non-ESRD [n = 247] and ESRD [n = 159]) in which the Ccr plots were normally distributed. The heritability (h(2)) of Ccr and age at ESRD (age(ESRD)) and the genetic correlations between these measures and their covariates were estimated. In patients without ESRD, a significant heritability was found for Ccr (h(2) = 0.42; P = 0.0015) after adjusting for age (P = 0.0001), systolic BP (P = 0.0006), and treatment with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (P = 0.00001). Birth year, gender, BMI, diastolic and mean BP, and pack-years of cigarette smoking did not significantly influence the heritability of this trait. In patients with ESRD, age(ESRD) provides a better measure than Ccr, which was very narrowly distributed. A significant heritability was found for age(ESRD) (h(2) = 0.78; P = 0.00009) in these latter patients. None of the above covariates influenced the heritability of this trait. It is concluded that a significant modifier gene effect influences the progression of renal disease in type 1 ADPKD.

Adult↗
PubMed2005

Breast cancer incidence: what do the figures mean?

UNLABELLED: ABSTRACT RATIONALE, AIMS AND OBJECTIVES: Against the background of a general rise in the incidence of breast cancer temporal variations appear in different age groups, including changes attributable to the introduction of breast screening. This paper attempts to distinguish the influence of breast screening and to examine any underlying patterns. METHODS: The incidence data published by the Office of National Statistics for England and Wales have been examined using the method of least squares regression. These data have been subjected to major revision: a new system was introduced in 1971. That year, therefore, has been taken as the starting point for the analyses. Regression lines were fitted from 1971, 1984 and 1988 (when breast screening was started). Results Between 1971 and 1984 breast cancer incidence was unchanged in women under 50 years. In all other age groups and time periods the incidence has risen throughout 1971-1999. The rate of increase remained constant for women over 64 but changed in 1984 for all women under 65 years. The rate of increase is rising exponentially with age since 1984 in the women under 65. The superimposed increases due to screening have been separated from the underlying rates. CONCLUSIONS: In the period surveyed there appears to have been a change in the rates of increase in incidence of breast cancer in women under 65 that dates from 1984. This change can be separated from the spurious increase due to breast screening. The rates in women over 64 have remained constant.

Adult↗
PubMed2004

Cerebral palsy registries.

Cerebral palsy (CP) registers appear to be appropriate tools for answering questions regarding the prevalence and characteristics of this common childhood disability. Registers are population databases issuing from multiple sources, relying on a clear definition and inclusion and exclusion criteria of CP, and requiring a mix of skills with the collaboration of obstetricians, pediatricians, and epidemiologists. In Europe alone there are 18 different CP registers or population data collections on CP, and collaborative research efforts exist through a European network. Data collection on CP has also been done in Australia (register), the United States (surveys), and Canada (register). Beside monitoring trends, other public health contributions of CP registers might be to reduce the frequency of CP and to improve the quality of life of children with CP. CP registers are useful to clinicians by enabling them to identify subgroups of children requiring specific etiologic investigations, and also to provide more accurate information to the parents of children with CP.

Cerebral Palsy↗
PubMed2004

Cerebral palsy of post-neonatal origin: characteristics and risk factors.

We aimed to study the rates and trends over time of children with cerebral palsy (CP) of post-neonatal origin (arising more than 28 days after birth, and before the age of 25 months), to examine their aetiology and associated significant risk factors, and to compare them with other CP cases. Children with post-neonatal CP born 1976-90 were identified from a European database and seven registers were included (Surveillance of Cerebral Palsy in Europe collaboration). Using a previously published classification it was possible to allocate an aetiology to 99% of cases. The prevalence rate of post-neonatal CP was 1.26 per 10 000 live births and a significant decrease was observed over the period 1976-90 (P = 0.011). Infection accounted for 50%, vascular episodes for 20% and head injury for 18% of the cases. Although there has been little change in the profile of underlying causes in this period, within the infection group, a significant downward trend was observed for Reye's syndrome (P < 0.001) and non-central nervous system (non-CNS) infection (P = 0.004), but not for meningitis/encephalitis. There was evidence of some increased risk of post-neonatal CP among children with low birthweight (<2500 g) (P < 0.001). Overall children with CP of post-neonatal origin showed a more severe functional pattern than non-post-neonatal CP children. In order to ascertain the impact of public health and other preventive measures aimed at reducing the frequency of brain injury in the first 2 years after birth, it is necessary to continue to monitor the frequency and characteristics of children with post-neonatal CP into the 1990s.

Age of Onset↗
PubMed2004

Behavioral and emotional adjustment of teenagers in mainstream school who were born before 29 weeks' gestation.

OBJECTIVES: To investigate behavioral and emotional problems and positive adjustment of 15-to 16-year-olds who were born at extremely low gestational age (ELGA), from the perspective of parents, teachers, and teenagers. METHODS: Prospective follow-up was conducted of birth cohorts, with classroom control subjects. All infants who were born before 29 weeks in 1983-1984 (mean gestational age: 27 weeks) to mothers who resided in 3 regions of the United Kingdom were studied. A total of 82% (179 of 218) of survivors were traced at age 15 to 16. The 150 in mainstream school were compared with age- and gender-matched classroom control subjects (n = 108). Behavioral and emotional problems, delinquency, peer relations, self-esteem, and hobbies, were assessed by standardized, well-validated instruments, including the Strengths and Difficulties Questionnaire, administered by mail to parents, teenagers, and teachers. RESULTS: Parents were more likely to rate ELGA teenagers than control subjects as in the "abnormal" range for hyperactivity (8% vs 1%; difference: 7%; (95% confidence interval [CI]: 2-12), peer relationship problems (19% vs 5%; difference: 14%; 95% CI: 6-21), and emotional problems (18% vs 7%; difference: 11%; 95% CI: 3-19), but not conduct problems (10% vs 5%; difference: 5%; 95% CI: -1 to 12)). Teachers reported a similar pattern. In contrast, compared with control subjects, ELGA teenagers did not rate themselves as having more problems with peers, hyperactivity, conduct, depression, or low self-esteem. They reported more emotional problems but less delinquency, alcohol, cannabis, and other drug use. CONCLUSIONS: Compared with mainstream classmates, children who are born extremely early continue to have higher levels of parent- and teacher-reported emotional, attentional, and peer problems well into their teens. However, despite these problems, they do not show signs of more serious conduct disorders, delinquency, drug use, or depression.

Adolescent↗
PubMed2003

Cerebral palsy and intrauterine growth in single births: European collaborative study.

BACKGROUND: Cerebral palsy seems to be more common in term babies whose birthweight is low for their gestational age at delivery, but past analyses have been hampered by small datasets and Z-score calculation methods. METHODS: We compared data from ten European registers for 4503 singleton children with cerebral palsy born between 1976 and 1990 with the number of births in each study population. Weight and gestation of these children were compared with reference standards for the normal spread of gestation and weight-for-gestational age at birth. FINDINGS: Babies of 32-42 weeks' gestation with a birthweight for gestational age below the 10th percentile (using fetal growth standards) were 4-6 times more likely to have cerebral palsy than were children in a reference band between the 25th and 75th percentiles. In children with a weight above the 97th percentile, the increased risk was smaller (from 1.6 to 3.1), but still significant. Those with a birthweight about 1 SD above average always had the lowest risk of cerebral palsy. A similar pattern was seen in those with unilateral or bilateral spasticity, as in those with a dyskinetic or ataxic disability. In babies of less than 32 weeks' gestation, the relation between weight and risk was less clear. INTERPRETATION: The risk of cerebral palsy, like the risk of perinatal death, is lowest in babies who are of above average weight-for-gestation at birth, but risk rises when weight is well above normal as well as when it is well below normal. Whether deviant growth is the cause or a consequence of the disability remains to be determined.

Birth Weight↗
PubMed2003

Cerebral palsy rates among low-birthweight infants fell in the 1990s.

Using a population-based register, this study sought to ascertain changes in the rate and severity of cerebral palsy (CP) in a geographically defined area of the UK among infants weighing less than 1500 g and born between 1984 and 1995. There were 417414 live births in the area, which included Berkshire, Buckinghamshire, Northamptonshire, and Oxfordshire. Of the 898 children with CP (526 males, 372 females), 194 (21.6%) weighed less than 1500 g at birth. The overall CP rate for neonatal survivors fell from 2.5 out of every 1000 in 1984 to 1986 to 1.7 in 1993 to 1995. The rate for those weighing less than 1000 g rose to 90 out of every 1000 neonatal survivors in 1987 to 1989 and then fell to 57 in 1993 to 1995. A similar pattern is seen among infants weighing 1000 to 1499 g at birth, the rate rising to 77 in 1987 to 1988 and then falling to 40 in 1993 to 1995. The rate of severe motor disability among infants weighing less than 1500 g also decreased (24.6 in 1984-1986 to 12.5 in 1993-1995). The relation of these findings to changes in perinatal care in the early 1990s is not known.

Cerebral Palsy↗
PubMed2003

Genotype-renal function correlation in type 2 autosomal dominant polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is a common Mendelian disorder that affects approximately 1 in 1000 live births. Mutations of two genes, PKD1 and PKD2, account for the disease in approximately 80 to 85% and 10 to 15% of the cases, respectively. Significant interfamilial and intrafamilial renal disease variability in ADPKD has been well documented. Locus heterogeneity is a major determinant for interfamilial disease variability (i.e., patients from PKD1-linked families have a significantly earlier onset of ESRD compared with patients from PKD2-linked families). More recently, two studies have suggested that allelic heterogeneity might influence renal disease severity. The current study examined the genotype-renal function correlation in 461 affected individuals from 71 ADPKD families with known PKD2 mutations. Fifty different mutations were identified in these families, spanning between exon 1 and 14 of PKD2. Most (94%) of these mutations were predicted to be inactivating. The renal outcomes of these patients, including the age of onset of end-stage renal disease (ESRD) and chronic renal failure (CRF; defined as creatinine clearance < or = 50 ml/min, calculated using the Cockroft and Gault formula), were analyzed. Of all the affected individuals clinically assessed, 117 (25.4%) had ESRD, 47 (10.2%) died without ESRD, 65 (14.0%) had CRF, and 232 (50.3%) had neither CRF nor ESRD at the last follow-up. Female patients, compared with male patients, had a later mean age of onset of ESRD (76.0 [95% CI, 73.8 to 78.1] versus 68.1 [95% CI, 66.0 to 70.2] yr) and CRF (72.5 [95% CI, 70.1 to 74.9] versus 63.7 [95% CI, 61.4 to 66.0] yr). Linear regression and renal survival analyses revealed that the location of PKD2 mutations did not influence the age of onset of ESRD. However, patients with splice site mutations appeared to have milder renal disease compared with patients with other mutation types (P < 0.04 by log rank test; adjusted for the gender effect). Considerable renal disease variability was also found among affected individuals with the same PKD2 mutations. This variability can confound the determination of allelic effects and supports the notion that additional genetic and/or environmental factors may modulate the renal disease severity in ADPKD.

Adult↗
PubMed2003

A case-control study of vanishing twin as a risk factor for cerebral palsy.

It has been hypothesized that cerebral palsy of unknown etiology is the result of the death of an unrecognized co-twin--a vanishing twin--in early gestation. We conducted a case-control study of vanishing twin as a risk factor for cerebral palsy of unknown etiology in women who had an obstetric ultrasound during pregnancy. Among mothers of cases, one of 86 had evidence of a vanishing twin on ultrasound, as compared to two of 381 control mothers (odds ratio [OR] 2.2, 95% confidence interval [CI] 0.2-24.8; p = 0.5). Bleeding in early pregnancy, which may indicate the loss of a co-twin, was reported by 14 case mothers and 46 control mothers (OR 1.6, 95% CI 0.8-3.0; p = 0.3). On the basis of results presented here, the vanishing twin syndrome is unlikely to account for a high proportion of cases of cerebral palsy, but there is insufficient statistical power to draw firm conclusions.

Adult↗
PubMed2003

Cerebral palsy and clinical negligence litigation: a cohort study.

OBJECTIVE: To compare the prevalence of criteria suggesting acute intrapartum hypoxia in children with cerebral palsy who have and have not been the subjects of clinical negligence legal claims. DESIGN: Nested cohort study within a geographically defined cohort. SETTING: The former Oxfordshire Health Authority. POPULATION: Singleton children with cerebral palsy born between 1984 and 1993, excluding cases with a recognised postnatal cause for cerebral palsy. METHODS: Retrospective review of medical records by blinded observer. MAIN OUTCOME MEASURES: Three 'essential' criteria defined by the International Cerebral Palsy Task Force which identify acute intrapartum hypoxia. RESULTS: One-fifth (27/138) of all singleton cerebral palsy children were the subject of a legal claim. The presence of all three criteria was significantly more likely to lead to a legal claim (P < 0.01), but in 74% (20/27) of claims, all three were not fulfilled and 36% (4/11) of those satisfying all three criteria did not claim. At least one of the three criteria was met in 82% (91/111) of the cases where there was no claim. Data on fetal or neonatal arterial blood gases were available in only 57% (78/138). Of the 27 claims, 12 were discontinued, 8 were settled and in 7 the legal process is still pending. The presence of the three essential criteria for acute intrapartum hypoxia did not increase the likelihood of a legal claim being settled. CONCLUSION: The prevalence of the 'template essential' criteria is high in all cases of cerebral palsy. Although the presence of all three essential criteria was more likely in the claims group, this did not appear to influence the outcome of a claim. It remains to be seen whether the existence of the template leads to change in the pattern of decisions made by the courts.

Adult↗
PubMed2002

Strabismus in children of birth weight less than 1701 g.

OBJECTIVE: To prospectively study infants of birth weight less than 1701 g in the East Midlands of England in the mid 1980s at 10 to 12 years of age to determine the incidence and risk factors for strabismus in children born preterm. METHODS: Low-birth-weight children (n = 572) who had been examined during the neonatal period were invited for a follow-up visit at age 10 to 12 years; 169 eleven-year-old schoolchildren born at full term were also recruited (the school cohort). RESULTS: Of the original 572 children, 293 consented to further examination. There was no significant difference between children who were examined and those who were not in terms of birth weight, gestational age, retinopathy of prematurity, and cranial ultrasound abnormalities. Compared with the school cohort (n = 5 [3.0%]; 95% confidence interval, 1.0%-9.1%), the low-birth-weight cohort had a significant increase in the prevalence of strabismus (n = 59 [20.1%]; 95% confidence interval, 15.9%-25.0%; P<.001). Compared with published data, there was a relative increase in the occurrence of exotropia in the low-birth-weight study cohort. Multivariate analysis, by backward logistic regression, indicated that retinopathy of prematurity, birth weight, cerebral palsy, anisometropia, and refractive error were all independently associated with strabismus (P<.05). CONCLUSIONS: The results of this study confirm the increased prevalence of strabismus in a low-birth-weight population. This study also provides more detailed information on risk factors and strabismus types.

Child↗
PubMed2002

Variations in the orthotic management of cerebral palsy.

OBJECTIVE: Anecdotal reports that children with cerebral palsy were provided different orthoses in two adjacent UK health districts were investigated using an observational comparative case study. METHOD: The populations were compared using an epidemiological register of children with cerebral palsy, which confirmed that a comparable health service response could be expected. Merging data from the register with the orthotic patient database facilitated comparison of the orthoses prescribed in each district. A survey questionnaire was used to gather the perceptions of clinicians in both districts to understand how each team decides which orthosis to prescribe. RESULTS: There was considerable variation in the types of orthoses prescribed between districts, and particularly of ankle foot orthoses. Survey respondents from the same profession described having the same roles, although clinicians expressed different responsibilities for initiating and sanctioning orthotic prescriptions in their district programmes. The survey also suggested that most clinicians were uncertain when prescribing orthoses, and clinical practice was therefore largely determined by professional preference. CONCLUSION: Defining the spectrum of activity limitation in geographically defined populations would enhance health services research and assist in the development of trials using different interventions to reduce those limitations.

Cerebral Palsy↗
PubMed2002

Cardiac and renal effects of standard versus rigorous blood pressure control in autosomal-dominant polycystic kidney disease: results of a seven-year prospective randomized study.

This study sought to investigate the cardiac and renal effects of rigorous versus standard BP control on autosomal-dominant polycystic kidney disease (ADPKD). A prospective, randomized, 7-yr study was performed to examine the effect of rigorous (<120/80 mmHg) versus standard (135-140/85-90 mmHg) BP control on left ventricular mass index (LVMI) and kidney function in 75 hypertensive ADPKD patients with left ventricular hypertrophy. LVMI was measured by echocardiogram at baseline and at 1 and 7 yr. Renal function was assessed by measuring serum creatinine and 24-h creatinine clearance every 6 mo for 3 yr, then annually for an additional 4 yr. The baseline characteristics were comparable in the two groups. During the study, average mean arterial pressure was 90 +/- 5 mmHg for the rigorous group and 101 +/- 4 mmHg for the standard group (P < 0.0001). The LVMI decreased by 21% in the standard group and by 35% in the rigorous group. A mixed model longitudinal data analysis revealed that rigorous BP control was significantly more effective in decreasing LVMI (P < 0.01). There was no statistically significant difference in renal function between the two groups. In conclusion, left ventricular hypertrophy, a major cardiovascular risk factor, was decreased to a significantly greater extent by rigorous than standard BP control. This finding has particular clinical importance because cardiovascular complications are the most common cause of death in ADPKD patients.

Adult↗
PubMed2002

A comparison of clinical variables that predict adverse outcome in term infants with severe respiratory failure randomised to a policy of extracorporeal membrane oxygenation or to conventional neonatal intensive care.

OBJECTIVE: To identify clinical variables predicting adverse outcome in a group of infants with severe respiratory failure who were randomized either to referral for extra-corporeal membrane oxygenation (ECMO) or to conventional neonatal intensive care within the United Kingdom. METHODS: Adverse outcome was defined by death or disability by four years of age. Receiver operator characteristic (ROC) plots were constructed for variables with continuous data and relative risk (RR) with 95% confidence intervals (CI) calculated for binominal data. RESULTS: Of variables measurable at trial entry, congenital diaphragmatic hernia and lower birthweight was also associated with increased mortality and morbidity. Seizures or supplementary oxygen at discharge were markers of disease course, which predicted a poorer outcome amongst survivors. These variables behaved similarly in the two trial groups. Those infants in the ECMO group with an episode of sepsis, established full sucking feeds after 14 days of age or a hospital stay over 30 days were at increased risk of disability. CONCLUSIONS: This study has identified clinical variables that predict adverse outcome for term infants with severe respiratory failure. The results may assist clinicians caring for these babies, when counseling their families and in the development of guidelines for neonatal ECMO.

Children with Disabilities↗
PubMed2002

Long-term ophthalmic outcome of low birth weight children with and without retinopathy of prematurity.

OBJECTIVE: A prospective study of retinopathy of prematurity (ROP) of 505 infants who weighed <1701 g at birth was undertaken in the mid-1980s. This cohort was traced at 10 to 12 years of age to determine how low birth weight alone and ROP might influence their ophthalmic outcome. METHODS: Outcome measures were 1) visual functions (visual acuity, contrast sensitivity, stereoacuity, perimetry, and color vision), 2) presence of strabismus, and 3), measurements of eye size and the dimensions of its components including refractive state. A total of 169 11-year-olds who were born at term were recruited as control subjects and examined under the same conditions. RESULTS: A total of 448 of the original cohort were traced, and 254 consented to a further examination. Compared with the control group, the follow-up cohort differed significantly with reduced visual functions and increased incidence of both myopia and strabismus. Compared with published data, eye size was smaller in the low birth weight cohort. To summarize the ophthalmic data, we defined ophthalmic morbidity as visual acuity below 0.0 log units or the presence of strabismus, myopia, color vision defect, or visual field defect. The rate of ophthalmic morbidity was 50.8% (n = 129/254) in the study cohort compared with 19.5% (n = 33/169) in the control group. The highest rate of ophthalmic morbidity was associated with severe ROP (stages 3/4), although those with no ROP had a less favorable outcome than the control group. CONCLUSION: This study shows that low birth weight children are at increased risk of visual impairments compared with children who are born at full term. Visual impairments are associated with low birth weight per se and severe ROP. Regressed mild ROP is only a risk factor for strabismus. The functional significance of these deficits is largely unknown.

Case-Control Studies↗