[Show abstract][Hide abstract] ABSTRACT: The DerSimonian and Laird approach (DL) is widely used for random effects meta-analysis, but this often results in inappropriate type I error rates. The method described by Hartung, Knapp, Sidik and Jonkman (HKSJ) is known to perform better when trials of similar size are combined. However evidence in realistic situations, where one trial might be much larger than the other trials, is lacking. We aimed to evaluate the relative performance of the DL and HKSJ methods when studies of different sizes are combined and to develop a simple method to convert DL results to HKSJ results.
We evaluated the performance of the HKSJ versus DL approach in simulated meta-analyses of 2-20 trials with varying sample sizes and between-study heterogeneity, and allowing trials to have various sizes, e.g. 25% of the trials being 10-times larger than the smaller trials. We also compared the number of "positive" (statistically significant at p < 0.05) findings using empirical data of recent meta-analyses with > =3 studies of interventions from the Cochrane Database of Systematic Reviews.
The simulations showed that the HKSJ method consistently resulted in more adequate error rates than the DL method. When the significance level was 5%, the HKSJ error rates at most doubled, whereas for DL they could be over 30%. DL, and, far less so, HKSJ had more inflated error rates when the combined studies had unequal sizes and between-study heterogeneity. The empirical data from 689 meta-analyses showed that 25.1% of the significant findings for the DL method were non-significant with the HKSJ method. DL results can be easily converted into HKSJ results.
Our simulations showed that the HKSJ method consistently results in more adequate error rates than the DL method, especially when the number of studies is small, and can easily be applied routinely in meta-analyses. Even with the HKSJ method, extra caution is needed when there are = <5 studies of very unequal sizes.
BMC Medical Research Methodology 02/2014; 14(1):25. · 2.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Guidelines advise primary granulocyte colony-stimulating factor (G-CSF) prophylaxis during chemotherapy if risk of febrile neutropenia (FN) is more than 20%, but this comes with considerable costs. We investigated the incremental costs and effects between two treatment strategies of primary pegfilgrastim prophylaxis.
Our economic evaluation used a health care perspective and was based on a randomized study in patients with breast cancer with increased risk of FN, comparing primary G-CSF prophylaxis throughout all chemotherapy cycles (G-CSF 1-6 cycles) with prophylaxis during the first two cycles only (G-CSF 1-2 cycles). Primary outcome was cost effectiveness expressed as costs per patient with episodes of FN prevented.
The incidence of FN increased from 10% in the G-CSF 1 to 6 cycles study arm (eight of 84 patients) to 36% in the G-CSF 1 to 2 cycles study arm (30 of 83 patients), whereas the mean total costs decreased from € 20,658 (95% CI, € 20,049 to € 21,247) to € 17,168 (95% CI € 16,239 to € 18,029) per patient, respectively. Chemotherapy and G-CSF determined 80% of the total costs. As expected, FN-related costs were higher in the G-CSF 1 to 2 cycles arm. The incremental cost effectiveness ratio for the G-CSF 1 to 6 cycles arm compared with the G-CSF 1 to 2 cycles arm was € 13,112 per patient with episodes of FN prevented.
We conclude that G-CSF prophylaxis throughout all chemotherapy cycles is more effective, but more costly, compared with prophylaxis limited to the first two cycles. Whether G-CSF prophylaxis throughout all chemotherapy cycles is considered cost effective depends on the willingness to pay per patient with episodes of FN prevented.
Journal of Clinical Oncology 10/2013; · 18.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Contrary to the situation in early breast cancer, little is known about the prognostic relevance of the hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) in metastatic breast cancer. The objectives of this study were to present survival estimates and to determine the prognostic impact of breast cancer subtypes based on HR and HER2 status in a recent cohort of metastatic breast cancer patients, which is representative of current clinical practice. Patients diagnosed with metastatic breast cancer between 2007 and 2009 were included. Information regarding patient and tumor characteristics and treatment was collected. Patients were categorized in four subtypes based on the HR and HER2 status of the primary tumor: HR positive (+)/HER2 negative (-), HR+/HER2+, HR-/HER2+ and triple negative (TN). Survival was estimated using the Kaplan-Meier method. Cox proportional hazards model was used to determine the prognostic impact of breast cancer subtype, adjusted for possible confounders. Median follow-up was 21.8 months for the 815 metastatic breast cancer patients included; 66 % of patients had the HR+/HER2- subtype, 8 % the HR-/HER2+ subtype, 15 % the TN subtype and 11 % the HR+/HER2+ subtype. The longest survival was observed for the HR+/HER2+ subtype (median 34.4 months), compared to 24.8 months for the HR+/HER2- subtype, 19.8 months for the HR-/HER2+ subtype and 8.8 months for the TN subtype (P < 0.0001). In the multivariate analysis, subtype was an independent prognostic factor, as were initial site of metastases and metastatic-free interval. The HR+/HER2+ subtype was associated with the longest survival after diagnosis of distant metastases.
Breast Cancer Research and Treatment 10/2013; · 4.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Non-SN prediction models are frequently used in clinical decision making to identify patients that may not need axillary treatment, but these models still need to be validated by follow-up data. Our purpose was the validation of non-sentinel node (SN) prediction models in predicting regional recurrences in patients without axillary treatment.
We followed a cohort of 486 women with favorable primary tumor characteristics and pN0(i+)(sn) or pN1mi(sn) for median 4.5 years. None of the patients underwent axillary treatment. Based on four published non-SN prediction models, the threshold allowing separation into low versus high-risk on non-SN involvement was set at 10%.
Overall 5-year regional recurrence rate was 3.0% (SE, ±0.1%). Using the Tenon scoring system, 438 low-risk patients had a 5-year regional recurrence rate of 2.3% (±0.8%), and 48 high-risk patients a recurrence rate of 10.1% (±0.4%). The MSKCC nomogram identified 300 low-risk patients with a recurrence rate of 2.8% (±1.1%), versus 166 high-risk patients with a rate of 3.4% (±0.5%) (20 patients not assessable). The Stanford nomogram identified 21 high-risk patients without recurrence, and 465 low-risk patients with a 3.2% (±0.9%) recurrence rate. A Dutch model discriminated between 384 low-risk patients with a recurrence rate of 2.2% (±0.8%) and 102 high-risk patients with a rate of 6.3% (±2.9%).
The Tenon scoring system outperformed the other models as it identified the largest subgroup of patients with low recurrence rate. In patients resembling our cohort we would recommend axillary treatment if they had a Tenon score above 3.5.
European journal of surgical oncology: the journal of the European Society of Surgical Oncology and the British Association of Surgical Oncology 10/2013; · 2.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study was designed to determine whether delivering neo-adjuvant chemotherapy at a higher dose in a shorter period of time improves outcome of breast cancer patients.
Women with newly diagnosed breast cancer were randomly assigned to neoadjuvant chemotherapy of four cycles of doxorubicin and cyclophosphamide followed by four cycles of docetaxel (AC 60/600 - T 100mg/m(2)) or six cycles of TAC (75/50/500mg/m(2)) every 3 weeks. The primary endpoint was the pathologic complete response (pCR) rate, defined as no invasive tumour present in the breast.
In total, 201 patients were included. Baseline characteristics were well balanced. AC-T resulted in pCR in 21% and TAC in 16% of patients (odds ratio 1.44 (95% confidence interval (CI) 0.67-3.10). AC-T without primary granulocyte-colony stimulating factor (G-CSF) prophylaxis was associated with more febrile neutropenia compared to TAC with primary G-CSF prophylaxis (23% versus 9%), and with more grade 3/4 sensory neuropathy (5% versus 0%).
With a higher cumulative dose for the concurrent arm, no differences were observed between the two treatment arms with respect to pCR rate. The differential toxicity profile could partly be explained by different use of primary G-CSF prophylaxis.
European journal of cancer (Oxford, England: 1990) 07/2013; · 4.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Postural instability, recurrent falls and fear of falling are common in advanced Parkinson's disease (PD). We examined the impact of fall frequency, fear of falling, balance confidence and objectively measured balance impairment (using Tinetti's Mobility Index) on health-related quality of life (HrQoL) in PD. In 74 subjects HrQoL was assessed using the 39-item Parkinson's disease Quality of Life Questionnaire [PDQ-39]. Patients were interviewed using a validated falls questionnaire, addressing fall history, consequences of falls and fear of falling. Neurological examination included Hoehn and Yahr scale, the Unified Parkinson's disease Rating Scale and Tinetti's Mobility Index. Disease severity, age and gender explained 43% of the differences in HrQoL across patients (R2 = 0.43). The combination of these factors and each of the factors fear of falling, balance confidence and falls frequency lead to 55%, 50% and 45% of explained variation, respectively. The standardised regression coefficients of these risk factors were 0.34 (fear of falling), 0.28 (balance confidence) and 0.13 (fall frequency). This suggests that fear of falling is a more important determinant of HrQoL than actual falling. These results emphasise the importance of addressing fear of falling in the clinical management of PD, and the need for development of strategies to reduce fear of falling in intervention programs.
[Show abstract][Hide abstract] ABSTRACT: PURPOSEEarly breast cancer is commonly treated with anthracyclines and taxanes. However, combining these drugs increases the risk of myelotoxicity and may require granulocyte colony-stimulating factor (G-CSF) support. The highest incidence of febrile neutropenia (FN) and largest benefit of G-CSF during the first cycles of chemotherapy lead to questions about the effectiveness of continued use of G-CSF throughout later cycles of chemotherapy. PATIENTS AND METHODS
In a multicenter study, patients with breast cancer who were considered fit enough to receive 3-weekly polychemotherapy, but also had > 20% risk for FN, were randomly assigned to primary G-CSF prophylaxis during the first two chemotherapy cycles only (experimental arm) or to primary G-CSF prophylaxis throughout all chemotherapy cycles (standard arm). The noninferiority hypothesis was that the incidence of FN would be maximally 7.5% higher in the experimental compared with the standard arm.ResultsAfter inclusion of 167 eligible patients, the independent data monitoring committee advised premature study closure. Of 84 patients randomly assigned to G-CSF throughout all chemotherapy cycles, eight (10%) experienced an episode of FN. In contrast, of 83 patients randomly assigned to G-CSF during the first two cycles only, 30 (36%) had an FN episode (95% CI, 0.13 to 0.54), with a peak incidence of 24% in the third cycle (ie, first cycle without G-CSF prophylaxis). CONCLUSION
In patients with early breast cancer at high risk for FN, continued use of primary G-CSF prophylaxis during all chemotherapy cycles is of clinical relevance and thus cannot be abandoned.
Journal of Clinical Oncology 04/2013; · 18.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Reperfusion is mandatory after ischemia, but also triggers ischemia-reperfusion (IR)-injury. Ischemic preconditioning (IPC) can limit endothelial IR-injury. Nonetheless, translation of IPC to the clinical arena is often disappointing. Since application of IPC typically relates to older patients, efficacy of IPC may be attenuated with aging. Objective. To examine the impact of advanced age on the ability of IPC to protect against endothelial dysfunction due to IR-injury. Methods. We included 15 healthy young (20-25 years) and 15 older men (68-77 years). We examined brachial artery endothelial function using flow mediated dilation (FMD) before and after arm IR (induced by inflation of an upper arm blood pressure cuff for 20 minutes and 15 minutes of reperfusion). In a randomised order, IR was preceded by IPC or a control-intervention consisting of 3 cycles of 5-minute upper arm cuff inflation to 220 or 20 mmHg, respectively. Results. In young men, FMD decreased significantly after IR (6.4±2.7% to 4.4±2.5%). This decrease was not present when IR was preceded by IPC (5.9±2.3 to 5.6±2.5). IPC-induced protection appeared to be significantly reduced in the elderly patients (P=0.04). Although FMD decreased after IR in older men (3.5±1.7 to 2.5±1.0), IPC could not prevent this (3.7±2.1 to 2.2±1.1). Conclusion. This study is the first to observe in humans in vivo that older age is associated with an abolished effect of IPC to protect against endothelial dysfunction after ischaemia-reperfusion in the brachial artery. This provides a possible explanation for the problematic translation of strategies that reduce IR-injury to clinic.
AJP Heart and Circulatory Physiology 04/2013; · 3.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Occupational therapists may have an added value in the care of patients with Parkinson's disease whose daily functioning is compromised, as well as for their immediate caregivers. Evidence for this added value is inconclusive due to a lack of rigorous studies. The aim of this trial is to evaluate the (cost) effectiveness of occupational therapy in improving daily functioning of patients with Parkinson's disease. METHODS: A multicenter, assessor-blinded, two-armed randomized controlled clinical trial will be conducted, with evaluations at three and six months. One hundred ninety-two home-dwelling patients with Parkinson's disease and with an occupational therapy indication will be assigned to the experimental group or to the control group (2:1). Patients and their caregivers in the experimental group will receive ten weeks of home-based occupational therapy according to recent Dutch guidelines. The intervention will be delivered by occupational therapists who have been specifically trained to treat patients according to these guidelines. Participants in the control group will not receive occupational therapy during the study period. The primary outcome for the patient is self-perceived daily functioning at three months, assessed with the Canadian Occupational Performance Measure. Secondary patient-related outcomes include: objective performance of daily activities, self-perceived satisfaction with performance in daily activities, participation, impact of fatigue, proactive coping skills, health-related quality of life, overall quality of life, health-related costs, and effectiveness at six months. All outcomes at the caregiver level will be secondary and will include self-perceived burden of care, objective burden of care, proactive coping skills, overall quality of life, and care-related costs. Effectiveness will be evaluated using a covariance analysis of the difference in outcome at three months. An economic evaluation from a societal perspective will be conducted, as well as a process evaluation. DISCUSSION: This is the first large-scale trial specifically evaluating occupational therapy in Parkinson's disease. It is expected to generate important new information about the possible added value of occupational therapy on daily functioning of patients with Parkinson's disease.Trial registration: clinicaltrials.gov: NCT01336127.
[Show abstract][Hide abstract] ABSTRACT: To evaluate whether a multifaceted behavioural change programme increases physical activities in patients with Parkinson's disease.
Multicentre randomised controlled trial.
32 community hospitals in the Netherlands, collaborating in a nationwide network (ParkinsonNet).
586 sedentary patients with idiopathic Parkinson's disease aged between 40 and 75 years with mild to moderate disease severity (Hoehn and Yahr stage ≤3).
Patients were randomly assigned to the ParkFit programme or a matched general physiotherapy intervention. ParkFit is a multifaceted behavioural change programme, designed specifically to achieve an enduring increase in the level of physical activity (coaches using motivational strategies; ambulatory feedback).
The primary endpoint was the level of physical activity, measured every six months with a standardised seven day recall (LASA physical activity questionnaire-LAPAQ). Secondary endpoints included two other measures of physical activity (activity diary and ambulatory activity monitor), quality of life (Parkinson's disease questionnaire-PDQ-39), and fitness (six minute walk test).
540 (92.2%) patients completed the primary outcome. During follow-up, overall time spent on physical activities (LAPAQ) was comparable between the groups (adjusted group difference 7%, 95% confidence interval -3 to 17%; P=0.19). Analyses of three secondary outcomes indicated increased physical activity in ParkFit patients, as suggested by the activity diary (difference 30%; P<0.001), the activity monitor (difference 12%; P<0.001), and the six minute walk test (difference 4.8 m; P=0.05). PDQ-39 did not differ between ParkFit patients and controls (difference -0.9 points; P=0.14). The number of fallers was comparable between ParkFit patients (184/299; 62%) and controls (191/287; 67%).
The ParkFit behavioural change programme did not increase overall physical activity, as measured with the LAPAQ. The analysis of the secondary endpoints justifies further work into the possible merits of behavioural change programmes to increase physical activities in daily life in Parkinson's disease.
Clinical trials NCT00748488.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: With this study we aimed to design validated outcome prediction models in moderate and severe traumatic brain injury (TBI) using demographic, clinical, and radiological parameters. METHODS: Seven hundred consecutive moderate or severe TBI patients were included in this observational prospective cohort study. After inclusion, clinical data were collected, initial head computed tomography (CT) scans were rated, and at 6 months outcome was determined using the extended Glasgow Outcome Scale. Multivariate binary logistic regression analysis was applied to evaluate the association between potential predictors and three different outcome endpoints. The prognostic models that resulted were externally validated in a national Dutch TBI cohort. RESULTS: In line with previous literature we identified age, pupil responses, Glasgow Coma Scale score and the occurrence of a hypotensive episode post-injury as predictors. Furthermore, several CT characteristics were associated with outcome; the aspect of the ambient cisterns being the most powerful. After external validation using Receiver Operating Characteristic (ROC) analysis our prediction models demonstrated adequate discriminative values, quantified by the area under the ROC curve, of 0.86 for death versus survival and 0.83 for unfavorable versus favorable outcome. Discriminative power was less for unfavorable outcome in survivors: 0.69. CONCLUSIONS: Outcome prediction in moderate and severe TBI might be improved using the models that were designed in this study. However, conventional demographic, clinical and CT variables proved insufficient to predict disability in surviving patients. The information that can be derived from our prediction rules is important for the selection and stratification of patients recruited into clinical TBI trials.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: In Parkinson's disease (PD), the motor presentation characterised by postural instability/gait difficulties (PIGD) heralds accelerated motor, functional and cognitive decline, as compared with the more benign tremor-dominant (TD) variant. This makes the PIGD complex an attractive target for the discovery of prognostic biomarkers in PD. OBJECTIVE: To explore in vivo whether variability in brain amyloid-β (Aβ) metabolism affects the initial motor presentation in PD. METHODS: We quantified cerebrospinal fluid (CSF) concentrations and ratios of Aβ42, Aβ40 and Aβ38 using a triplex immunoassay in 99 patients with de novo PD with the PIGD phenotype (n=39) or the TD phenotype (n=60). All patients underwent standardised assessments of motor and neuropsychological function and cerebral MRI. 46 age-matched normal controls served as external reference. RESULTS: Patients with PD with the PIGD phenotype had significantly reduced CSF Aβ42, Aβ38, Aβ42/40 and Aβ38/40 levels compared with patients with the TD phenotype and controls. CSF marker levels in patients with PD-TD did not differ from those in controls. Multivariate regression models demonstrated significant associations of CSF Aβ markers with severity of PIGD and lower limb bradykinesia in patients with PD, independently from age, MRI white matter hyperintensities and cognition. No associations were found between CSF markers and other motor features. CONCLUSIONS: Motor heterogeneity in de novo PD independently relates to CSF Aβ markers, with low levels found in patients with the PIGD presentation. This suggests that disturbed Aβ metabolism has an effect on PD beyond cognition and may contribute to the variable rate of motor and functional decline in PD.
Journal of neurology, neurosurgery, and psychiatry 10/2012; · 4.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is debate whether clinical trials with suboptimal power are justified and whether results from large studies are more reliable than the (combined) results of smaller trials. We quantified the error rates for evaluations based on single conventionally powered trials (80% or 90% power) versus evaluations based on the random-effects meta-analysis of a series of smaller trials. When a treatment was assumed to have no effect but heterogeneity was present, the error rates for a single trial were increased more than 10-fold above the nominal rate, even for low heterogeneity. Conversely, for meta-analyses on a series of trials, the error rates were correct. When selective publication was present, the error rates were always increased, but they still tended to be lower for a series of trials than single trials. We conclude that evidence of efficacy based on a series of (smaller) trials, may lower the error rates compared with using a single well-powered trial. Only when both heterogeneity and selective publication can be excluded, a single trial is able to provide conclusive evidence.
Statistical Methods in Medical Research 10/2012; · 2.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Post-traumatic amnesia (PTA) is a key symptom of traumatic brain injury (TBI). Accurate assessment of PTA is imperative in guiding clinical decision making. Our aim was to develop and externally validate a short, examiner independent and practical PTA scale, by selecting the most discriminative items from existing scales and using a three-word memory test.
Mild, moderate and severe TBI patients and control subjects were assessed in two separate cohorts, one for derivation and one for validation, using a questionnaire comprised of items from existing PTA scales. We tested which individual items best discriminated between TBI patients and controls, represented by sensitivity and specificity. We then created our PTA scale based on these results. This new scale was externally evaluated for its discriminative value using Receiver Operating Characteristic (ROC) analysis and compared to existing PTA scales.
The derivation cohort included 126 TBI patients and 31 control subjects; the validation cohort consisted of 132 patients and 30 controls. A set of seven items was eventually selected to comprise the new PTA scale: age, name of hospital, time, day of week, month, mode of transport and recall of three words. This scale demonstrated adequate discriminative values compared to existing PTA scales on three consecutive administrations in the validation cohort.
We introduce a valid, practical and examiner independent PTA scale, which is suitable for mild TBI patients at the emergency department and yet still valuable for the follow-up of more severely injured TBI patients.
[Show abstract][Hide abstract] ABSTRACT: Aim:To evaluate the feasibility of a randomized controlled trial including process and potential impact of occupational therapy in Parkinson's disease.Design:Process and outcome were quantitatively and qualitatively evaluated in an exploratory multicentre, two-armed randomized controlled trial at three months.Participants:Forty-three community-dwelling patients with Parkinson's disease and difficulties in daily activities, their primary caregivers and seven occupational therapists.Intervention:Ten weeks of home-based occupational therapy according to the Dutch guidelines of occupational therapy in Parkinson's disease versus no occupational therapy in the control group.Main measures:Process evaluation measured accrual, drop-out, intervention delivery and protocol adherence. Primary outcome measures of patients assessed daily functioning: Canadian Occupational Performance Measure (COPM) and Assessment of Motor and Process Skills. Primary outcome for caregivers was caregiver burden: Zarit Burden Inventory. Participants' perspectives of the intervention were explored using questionnaires and in-depth interviews.Results:Inclusion was 23% (43/189), drop-out 7% (3/43) and unblinding of assessors 33% (13/40). Full intervention protocol adherence was 74% (20/27), but only 60% (71/119) of baseline Canadian Occupational Performance Measure priorities were addressed in the intervention. The outcome measures revealed negligible to small effects in favour of the intervention group. Almost all patients and caregivers of the intervention group were satisfied with the results. They perceived: 'more grip on the situation' and used 'practical advices that make life easier'. Therapists were satisfied, but wished for a longer intervention period.Conclusions:The positive perceived impact of occupational therapy warrants a large-scale trial. Adaptations in instructions and training are needed to use the Canadian Occupational Performance Measure as primary outcome measure.
[Show abstract][Hide abstract] ABSTRACT: Balance control in Parkinson's disease is often studied using dynamic posturography, typically with serial identical balance perturbations. Because subjects can learn from the first trial, the magnitude of balance reactions rapidly habituates during subsequent trials. Changes in this habituation rate might yield a clinically useful marker. We studied balance reactions in Parkinson's disease using posturography, specifically focusing on the responses to the first, fully unpractised balance disturbance, and on the subsequent habituation rates.
Eight Parkinson patients and eight age- and gender-matched controls received eight consecutive toe-up rotations of a support-surface. Balance reactions were measured with a motion analysis system and converted to centre of mass displacements (primary outcome).
Mean centre of mass displacement during the first trial was 51% greater in patients than controls (P=0.019), due to excessive trunk flexion and greater ankle plantar-flexion. However, habituated trials were comparable in both groups. Patients also habituated slower: controls were fully habituated at trial 2, whereas habituation in patients required up to five trials (P=0.004). The number of near-falls during the first trial was significantly correlated with centre of mass displacement during the first trial and with habituation rate.
Higher first trial reactions and a slow habituation rate discriminated Parkinson's patients from controls, but habituated trials did not. Further work should demonstrate whether this also applies to clinical balance tests, such as the pull test, and whether repeated delivery of such tests offers better diagnostic value for evaluating fall risks in parkinsonian patients.
[Show abstract][Hide abstract] ABSTRACT: In classical congenital adrenal hyperplasia (CAH), elevation of adrenal androgens leads to accelerated growth and bone maturation with compromised adult height. In untreated children with non-classical CAH (NC-CAH), in which adrenal androgens are generally only slightly increased, growth velocity may not be significantly elevated.
Twenty-four patients were included and divided into a symptomatic and an asymptomatic group. Height was expressed as height standard deviation scores (HSDS) and corrected for target height (HSDS-THSDS). Bone maturation was expressed as bone age acceleration (BA(c) = bone age - calendar age). Linear mixed models with random factor patient were used for the analysis of growth and bone age.
In symptomatic patients (n = 17), HSDS-THSDS only slightly increased by 0.06 SDS per year (95% CI 0.02-0.10). Mean BA(c) was 2.21 years (SDS 0.66, p < 0.0001). In asymptomatic patients (n = 7), no significant growth acceleration or BA(c) was found.
In untreated NC-CAH children, growth acceleration is small and generally not visible on their growth charts. BA(c) is more pronounced. Therefore, the absence of an increase in growth velocity does not exclude the diagnosis of NC-CAH. When considering this diagnosis, bone age acceleration should also be taken into account.
Hormone Research in Paediatrics 04/2012; 77(3):164-9. · 1.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: For cluster randomized trials with a continuous outcome, the sample size is often calculated as if an analysis of the outcomes at the end of the treatment period (follow-up scores) would be performed. However, often a baseline measurement of the outcome is available or feasible to obtain. An analysis of covariance (ANCOVA) using both the baseline and follow-up score of the outcome will then have more power. We calculate the efficiency of an ANCOVA analysis using the baseline scores compared with an analysis on follow-up scores only. The sample size for such an ANCOVA analysis is a factor r2 smaller, where r is the correlation of the cluster means between baseline and follow-up. This correlation can be expressed in clinically interpretable parameters: the correlation between baseline and follow-up of subjects (subject autocorrelation) and that of clusters (cluster autocorrelation). Because of this, subject matter knowledge can be used to provide (range of) plausible values for these correlations, when estimates from previous studies are lacking. Depending on how large the subject and cluster autocorrelations are, analysis of covariance can substantially reduce the number of clusters needed.
Statistics in Medicine 04/2012; 31(20):2169-78. · 2.04 Impact Factor