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PubMed2006

A longitudinal functional magnetic resonance imaging study of language development in children 5 to 11 years old.

OBJECTIVE: Language skills continue to develop rapidly in children during the school-age years, and the "snapshot" view of the neural substrates of language provided by current neuroimaging studies cannot capture the dynamic changes associated with brain development. The aim of this study was to conduct a 5-year longitudinal investigation of language development using functional magnetic resonance imaging in healthy children. METHODS: Thirty subjects enrolled at ages 5, 6, or 7 were examined annually for 5 years using a 3-Tesla magnetic resonance imaging scanner and a verb generation task. Data analysis was conducted based on a general linear model that was modified to investigate developmental changes whereas minimizing the potential for missing data. RESULTS: With increasing age, there is progressive participation in language processing by the inferior/middle frontal, middle temporal, and angular gyri of the left hemisphere and the lingual and inferior temporal gyri of the right hemisphere and regression of participation of the left posterior insula/extrastriate cortex, left superior frontal and right anterior cingulate gyri, and left thalamus. CONCLUSION: The age-related changes observed in this study provide evidence of increased neuroplasticity of language in this age group and may have implications for further investigations of normal and aberrant language development.

Algorithms↗
PubMed2004

Review of the professional medical liability insurance crisis: lessons from Missouri.

OBJECTIVE: This study was undertaken to document and generalize the professional liability insurance (PLI) crisis. STUDY DESIGN: Data analysis from physician surveys, Missouri Department of Insurance, and court records. RESULTS: In 2001-2002, many insurers stopped writing new and existing PLI. A survey found 1 in 7 physicians had their PLI terminated and/or application for new insurance denied. Average premiums increased 22% in 2001 and 60% in 2002. Accordingly, 50% of surveyed obstetricians took salary cuts, 18% secured loans, 9% liquidated assets, and 55% significantly limited their clinical services. An adverse court ruling caused insurers to double reserves. Incomplete data led the Missouri Department of Insurance to erroneously conclude a decrease in claim frequency and severity. In contrast, courthouse records and missing data sources revealed increased malpractice filings. PLI premiums continue to rise. CONCLUSION: Many life-saving specialists are being forced out of business. Specialists are less willing to care for emergency and indigent patients for fear of liability exposure. Legislative enactments leading to meaningful tort reform, public support, and judicial restraint must occur to save health care.

Defensive Medicine↗
PubMed2005

Cancer pain assessment in clinical trials. A review of the literature (1999-2002).

The aim of this review was to evaluate the methods of pain measurement in controlled clinical trials in oncology published between 1999 and 2002. An electronic literature search strategy was used according to established criteria applied to the Medline database and PubMed search engine. Articles were selected to include only studies that had chronic cancer pain as the primary or secondary objective of a controlled clinical trial. A specific evaluation scheme was used to examine how pain measurement methods were chosen and implemented in the study procedures. The search strategy identified 613 articles, and 68 were selected for evaluation. Most articles (69%) chose unidimensional pain measurement tools, such as visual analogue scales, numerical rating scales and verbal rating scales, whereas others used questionnaires. The implementation of the pain assessment method was problematic in many studies, especially as far as time frame of pain assessment (70%), administration modalities (46%), and use of non-validated measurement methods (10%). Design of study and data analysis were often unclear about the definition of pain outcome measure (40%), patient compliance with pain assessment (98%), and impact of missing data (56%). Statistical techniques were seldom appropriate to the type of data collected and often inadequate to describe the pain variable under study. It is clear from this review that most authors were aware of the need of valid pain measurement tools to be used in clinical trials. However, too often these tools were not appropriately used in the trial, or at least their use was not described with sufficient accuracy in the trial methods.

Chronic Disease↗
PubMed1996

Using clinical and functional data for quality improvement in outcomes measurement consortia.

BACKGROUND: Using standardized measures, American Group Practice Association care providers compiled a national database from which patients could be tracked, allowing for epidemiologic comparisons among treatments, sources of care, and results. Within five years, the consortia expanded from 6 to 55 clinics and from a focus on total hip replacement surgery to eight different health conditions. DATA COLLECTION PROCESS: Reflecting areas of significant public concern, high prevalence, high cost, or research needs, both patient- and provider-source data are collected at group practices at standardized intervals: 6 months, 12 months, and annually thereafter. OUTCOMES DATA MANAGEMENT AND REPORTING: A readily adaptable database infrastructure allows data-collection tools to adapt individual questions to changing conditions in the health care environment while maintaining the integrity of the whole structure. Aggregate-level reports complement individual clinics' own internal analysis efforts by providing a context for the interpretation of results. CASE STUDIES: In a total hip replacement consortium (including more than 2,300 patients), early findings have shown that patients do not fully recover from surgery as quickly as they themselves anticipated. In the cataract consortium, data scores on near, distant, day, night, glare, and overall vision scales improve considerably after cataract surgery, giving clinics a new tool to monitor and improve performance. In the asthma consortium, one clinic reevaluated the distribution of peak flow meters and the reasons for their underuse after noting the low number of patients in the clinic that had peak flow meters. LESSONS LEARNED: Provider participation in study design, instrumentation, data analysis, and feedback is important, and physician buy-in and support are critical to the success of any outcomes initiative. Missing data are the greatest limitations of a longitudinal data set and are difficult to collect through follow-up. There is still much to be learned about what functional status and well being measures can show about the relationship between health care services and patient health.

Asthma↗
PubMed2005

Error concealment for shape in MPEG-4 object-based video coding.

In asynchronus transfer mode networks, cell loss or channel errors can cause data to be dropped in the channel. When digital images/videos are transmitted over these networks, one must be able to reconstruct the missing data so that the impact of the errors is minimized. In this paper, we present an error-concealment technique for shape in MPEG-4 object-based video coding. This method, which is based on using global motion estimation and compensation techniques for boundary recovery, consists of three steps: (1) boundary extraction from shape; (2) boundary patching using global motion compensation; and (3) boundary filling to reconstruct the shape of the damaged video object planes. Global motion parameters are inserted as part of the USER_DATA field in the compressed stream and are utilized in reconstructing the damaged boundaries of compressed video object planes.

Algorithms↗
PubMed2003

A randomized controlled trial of intravenous aminophylline for atropine-resistant out-of-hospital asystolic cardiac arrest.

OBJECTIVES: Myocardial ischemia, during cardiopulmonary arrest, can lead to atropine-resistant bradyasystole from interstitial accumulation of endogenous adenosine. Aminophylline is a nonspecific adenosine receptor antagonist capable of reversing ischemia-induced bradyasystole in a variety of settings. The hypothesis of this study was that aminophylline improves the rate of return of spontaneous circulation (ROSC) in atropine-resistant asystolic out-of-hospital cardiac arrest when used early in the resuscitation effort. METHODS: This was a prospective, randomized, double-blinded, placebo-controlled trial set in an urban emergency medical services system serving a population of 250,000. All non-pregnant, normothermic adults suffering nontraumatic out-of-hospital cardiac arrest (February 1999 to August 2000) with asystole were eligible. Patients remaining in asystole after initial doses of epinephrine and atropine received either aminophylline 250 mg or matching placebo as a bolus injection through a peripheral intravenous line. All other aspects of the attempted resuscitation proceeded in accordance with standard Advanced Cardiac Life Support (ACLS) guidelines. A sample size of 102 patients was calculated to yield a power of 80% to show an absolute improvement of 25% in ROSC. The aminophylline and control groups were compared by calculating 95% confidence intervals (95% CIs) and the data were modeled using logistic regression. RESULTS: The investigators enrolled 112 consecutive patients. One subject was dropped prior to analysis because of missing data. Data for 111 patients were analyzed on an intention-to-treat basis. Baseline characteristics were similar for the two groups. Comparing the control and aminophylline groups, ROSC was achieved in 15.6% (95% CI = 6% to 29%) and 22.7% (95% CI = 13% to 35%), while reversal of asystole occurred in 26.7% (95% CI = 15% to 42%) and 40.9% (95% CI = 29% to 54%), respectively. Group allocation had an odds ratio of 1.8 (95% CI = 0.6 to 5.3) for ROSC. Witnessed arrest was an independent predictor of outcome with an odds ratio of 3.8 (95% CI = 1.3 to 11.2). CONCLUSIONS: Addition of aminophylline appears to be a promising new intervention in the ACLS treatment of atropine-resistant asystolic out-of-hospital cardiac arrest.

Advanced Cardiac Life Support↗
PubMed2006

Development of short and very short forms of the Children's Behavior Questionnaire.

Using data from 468 parents and taking into account internal consistency, breadth of item content, within-scale factor analysis, and patterns of missing data, we developed short (94 items, 15 scales) and very short (36 items, 3 broad scales) forms of the Children's Behavior Questionnaire (CBQ; Rothbart, Ahadi, & Hershey, 1994; Rothbart, Ahadi, Hershey, & Fisher, 2001), a well-established parent-report measure of temperament for children aged 3 to 8 years. We subsequently evaluated the forms with data from 1,189 participants. In mid/high-income and White samples, the CBQ short and very short forms demonstrated both satisfactory internal consistency and criterion validity, and exhibited longitudinal stability and cross-informant agreement comparable to that of the standard CBQ. Internal consistency was somewhat lower among African American and low-income samples for some scales. Very short form scales demonstrated acceptable internal consistency for all samples, and confirmatory factor analyses indicated marginal fit of the very short form items to a three-factor model.

Black People↗
PubMed1995

A surveillance study of clinical stage I nonseminomatous germ cell tumors of the testis: 10-year followup.

PURPOSE: We evaluate the 10-year results of a surveillance study of clinical stage I nonseminomatous germ cell tumors of the testis. MATERIALS AND METHODS: Between 1981 and 1984 we recruited 85 consecutive evaluable patients with nonseminomatous germ cell tumors of the testis and normal post-orchiectomy physical examination, chest x-rays, bipedal lymphangiography, abdominal scans and serum tumor markers. The patients were followed for at least 10 years after orchiectomy alone, which was performed elsewhere in 90% of the cases. RESULTS: The interval between visits was twice as long as it was scheduled. Relapses occurred in 25 patients (29.4%) after a median disease-free interval of 7 months (range 2 to 68). Five patients had further relapses and 3 (3.5%) died of cancer. Retroperitoneal relapses (19%) occurred later than lung relapses, and they were diagnosed when larger than 5 cm. in 7 patients. The percentage of embryonal carcinoma within the tumor associated with relapse (p = 0.008), T category (p = 0.023), scrotal violation (p = 0.042) and vascular invasion (p = 0.063) had a weak correlation but data on T category and vascular invasion were available for only some patients. CONCLUSIONS: Surveillance is a difficult type of study and missing data may compromise the therapeutic program based on prognostic factors.

Follow-Up Studies↗
PubMed2005

Sample size for a two-group comparison of repeated binary measurements using GEE.

Controlled clinical trials often randomize subjects to two treatment groups and repeatedly evaluate them at baseline and intervals across a treatment period of fixed duration. A popular primary objective in these trials is to compare the change rates in the repeated measurements between treatment groups. Repeated measurements usually involve missing data and a serial correlation within each subject. The generalized estimating equation (GEE) method has been widely used to fit the time trend in repeated measurements because of its robustness to random missing and mispecification of the true correlation structure. In this paper, we propose a closed form sample size formula for comparing the change rates of binary repeated measurements using GEE for a two-group comparison. The sample size formula is derived incorporating missing patterns, such as independent missing and monotone missing, and correlation structures, such as AR(1) model. We also propose an algorithm to generate correlated binary data with arbitrary marginal means and a Markov dependency and use it in simulation studies.

Algorithms↗
PubMed2004

Move over ANOVA: progress in analyzing repeated-measures data and its reflection in papers published in the Archives of General Psychiatry.

BACKGROUND: The analysis of repeated-measures data presents challenges to investigators and is a topic for ongoing discussion in the Archives of General Psychiatry. Traditional methods of statistical analysis (end-point analysis and univariate and multivariate repeated-measures analysis of variance [rANOVA and rMANOVA, respectively]) have known disadvantages. More sophisticated mixed-effects models provide flexibility, and recently developed software makes them available to researchers. OBJECTIVES: To review methods for repeated-measures analysis and discuss advantages and potential misuses of mixed-effects models. Also, to assess the extent of the shift from traditional to mixed-effects approaches in published reports in the Archives of General Psychiatry. DATA SOURCES: The Archives of General Psychiatry from 1989 through 2001, and the Department of Veterans Affairs Cooperative Study 425. STUDY SELECTION: Studies with a repeated-measures design, at least 2 groups, and a continuous response variable. DATA EXTRACTION: The first author ranked the studies according to the most advanced statistical method used in the following order: mixed-effects model, rMANOVA, rANOVA, and end-point analysis. DATA SYNTHESIS: The use of mixed-effects models has substantially increased during the last 10 years. In 2001, 30% of clinical trials reported in the Archives of General Psychiatry used mixed-effects analysis. CONCLUSIONS: Repeated-measures ANOVAs continue to be used widely for the analysis of repeated-measures data, despite risks to interpretation. Mixed-effects models use all available data, can properly account for correlation between repeated measurements on the same subject, have greater flexibility to model time effects, and can handle missing data more appropriately. Their flexibility makes them the preferred choice for the analysis of repeated-measures data.

Analysis of Variance↗
PubMed2005

Interventions to prevent hypothermia at birth in preterm and/or low birthweight babies.

BACKGROUND: Hypothermia incurred during routine postnatal resuscitation is a world-wide issue (across all climates), with associated morbidity and mortality. Keeping vulnerable preterm infants warm is problematic even when recommended routine thermal care guidelines are followed in the delivery suite. OBJECTIVES: To assess efficacy and safety of interventions, designed for prevention of hypothermia in preterm and/or low birthweight infants, applied within 10 minutes after birth in the delivery suite compared with routine thermal care. SEARCH STRATEGY: The standard search strategy of The Cochrane Collaboration was followed. Electronic databases were searched: MEDLINE (1966 to May Week 4 2004 ), CINAHL (1982 to May Week 4 2004), EMBASE (1974 to 09/07/04), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2004), Database of Abstracts of Reviews of Effects (DARE 1994 to July 2004), conference/symposia proceedings using ZETOC (1993 to July 2004), ISI proceedings (1990 to 09/07/2004) and OCLC WorldCat (July 2004). Identified articles were cross-referenced. No language restrictions were imposed. SELECTION CRITERIA: All trials using randomised or quasi-randomised allocations to test a specific intervention designed to prevent hypothermia, (apart from 'routine' thermal care) applied within 10 minutes after birth in the delivery suite to infants of < 37 weeks' gestational age or birthweight </=2500 g. DATA COLLECTION AND ANALYSIS: Methodological quality was assessed and data were extracted for important clinical outcomes including adverse effects of the intervention by at least three independent reviewers. Authors were contacted for missing data. Data were analysed using RevMan 4.2.5. Relative risk (RR), risk difference (RD) and number needed to treat (NNT) with 95% confidence limits were calculated for each dichotomous outcome and mean differences (MD) with 95% confidence limits for continuous outcomes. MAIN RESULTS: Six studies giving a total of 304 infants randomised and 295 completing the studies were included. Four comparisons to 'routine care' were undertaken within two categories: 1) barriers to heat loss (four studies): plastic wrap or bag (three), stockinet caps (one) and 2) external heat sources (two studies): skin-to-skin (one), transwarmer mattress (one). Plastic barriers were effective in reducing heat losses in infants < 28 weeks' gestation (three studies, n = 159; WMD 0.76 degrees C; 95% CI 0.49, 1.03) but not in the 28 to 31 week group. There was insufficient evidence to suggest that plastic wrap reduces the risk of death within hospital stay (three studies, n = 161; typical RR 0.63; 95% CI 0.32, 1.22; typical RD -0.09; 95% CI -0.20, 0.03). There was no evidence of a significant difference in major brain injury, mean duration of oxygen therapy or hospitalisation for infants < 29 weeks' gestation. Stockinet caps were not effective (borderline significant for infants < 2000 g birthweight) in reducing heat losses.Skin-to-skin care was shown to be effective in reducing the risk of hypothermia when compared to conventional incubator care for infants 1200 to 2199 g birthweight (one study, n = 31; RR 0.09; 95% CI 0.01, 0.64; NNT 2; 2 to 4). The transwarmer mattress significantly kept infants </=1500 g warmer and reduced the incidence of hypothermia on admission to NICU (one study, n = 24; RR 0.30; 95% CI 0.11, 0.83; NNT 2 range 2 to 4). AUTHORS' CONCLUSIONS: Plastic wraps or bags, skin-to-skin care and transwarmer mattresses all keep preterm infants warmer, leading to higher temperatures on admission to neonatal units and less hypothermia. Given the low NNT, consideration should be given to using these interventions in the delivery suite. However, the small numbers of infants and studies and the absence of long term follow-up mean that firm recommendations for clinical practice cannot be given. There is a need to conduct large, high quality randomised controlled trials looking at long-term outcomes.

Humans↗
PubMed2002

Direct long-term observation of kinesin processivity at low load.

The hand-over-hand stepping mechanism of kinesin at low loads is inadequately understood because the number of molecular steps taken per encounter with the microtubule is difficult to measure: optical traps do not register steps at zero load, while evanescent wave microscopy of single molecules of GFP-kinesin suffers from premature photobleaching. Obtaining low-load data is important because it can efficiently distinguish between alternative proposed mechanisms for molecular walking. We report a novel experiment that records the missing data. We fused kinesin to gelsolin, creating a construct that severs and caps rhodamine-phalloidin actin filaments, setting exactly one kinesin molecule on one end of each fluorescent actin filament. Single kinesin molecules labeled in this way can be tracked easily and definitively using a standard epifluorescence microscope. We use the new system to show that, contrary to a recent report, kinesin run length at low load is independent of ATP concentration in the muM to mM range of ATP concentration. Adding competitor ADP in the presence of saturating ATP decreases both velocity and run length. Based on these data, we propose a simplified model for the mechanism of processive stepping.

Actins↗
PubMed1996

Decline in self-reported dysphoria after treatment entry in inner-city cocaine addicts.

This study examined self-reported dysphoria in 82 consecutive admissions to intensive outpatient treatment for cocaine abuse on whom data for the Beck scales for depression, anxiety, and hopelessness were available for intake and 4 subsequent weeks with no more than 1 missing data point. Mean scores on the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI) decreased significantly between intake and Week 1, with no further significant changes from Weeks 1-4. Similar drops in the rate of clinically significant BDI and BAI scores also were observed. Scores on the Beck Hopelessness Scale (BHS) showed no significant changes. By Week 4, rates of clinically significant depression, anxiety, and hopelessness were similar (17%, 13%, and 16%, respectively). These findings suggest that assessing depression and anxiety using the BDI and BAI in this population should be postponed for at least 1 week after intake and that intake levels of self-reported mood may be inappropriate baseline measures for evaluating treatment effects.

Adult↗
PubMedDate not supplied

Transfer of intra-aortic balloon pump-dependent patients by paramedics.

This prospective case series describes the experience of a specially trained critical care paramedic transfer program that transports intra-aortic balloon pump (IABP)-dependent patients to definitive cardiac surgical care without additional medical escorts. Paramedics complete a standard ambulance patient care report and a quality management report for each IABP-dependent patient transported. All patient care reports were routinely screened for calls involving IABP-dependent patients to ensure all calls were captured. Demographic, patient care, adverse event, and transfer-related data were collected prospectively. The program manager and medical director independently examined all reports for quality of care and occurrence of adverse events. Missing data were obtained from paramedic crews and referring facilities. The IABP program transported 29 patients during its first 24 months. The mean patient age was 63.4 +/- 10.4 years, and the majority were male (25 of 29; 86.2%). The most common indications for IABP insertion were bridge to definitive surgical care (17; 58.6%) and cardiogenic shock (13; 44.8%). The mean out-of-hospital time was 39.9 +/- 26.1 minutes. There were 22 complications in 11 patients. Paramedics successfully managed all complications. There was no persistent life-threatening patient-related complication or IABP-related malfunction, and no patient died during transport. This case series demonstrates that specially trained critical care paramedics can safely IABP-dependent patients to definitive cardiac surgical care without additional medical escorts.

Aged↗
PubMed2006

Nonlinear approximation based image recovery using adaptive sparse reconstructions and iterated denoising--Part II: Adaptive algorithms.

We combine the main ideas introduced in Part I with adaptive techniques to arrive at a powerful algorithm that estimates missing data in nonstationary signals. The proposed approach operates automatically based on a chosen linear transform that is expected to provide sparse decompositions over missing regions such that a portion of the transform coefficients over missing regions are zero or close to zero. Unlike prevalent algorithms, our method does not necessitate any complex preconditioning, segmentation, or edge detection steps, and it can be written as a progression of denoising operations. We show that constructing estimates based on nonlinear approximants is fundamentally a nonconvex problem and we propose a progressive algorithm that is designed to deal with this issue directly. The algorithm is applied to images through an extensive set of simulation examples, primarily on missing regions containing textures, edges, and other image features that are not readily handled by established estimation and recovery methods. We discuss the properties required of good transforms, and in conjunction, show the types of regions over which well-known transforms provide good predictors. We further discuss extensions of the algorithm where the utilized transforms are also chosen adaptively, where unpredictable signal components in the progressions are identified and not predicted, and where the prediction scenario is more general.

Algorithms↗
PubMed2006

Inferential backbone assignment for sparse data.

This paper develops an approach to protein backbone NMR assignment that effectively assigns large proteins while using limited sets of triple-resonance experiments. Our approach handles proteins with large fractions of missing data and many ambiguous pairs of pseudoresidues, and provides a statistical assessment of confidence in global and position-specific assignments. The approach is tested on an extensive set of experimental and synthetic data of up to 723 residues, with match tolerances of up to 0.5 ppm for Calpha and Cbeta resonance types. The tests show that the approach is particularly helpful when data contain experimental noise and require large match tolerances. The keys to the approach are an empirical Bayesian probability model that rigorously accounts for uncertainty in the data at all stages in the analysis, and a hybrid stochastic tree-based search algorithm that effectively explores the large space of possible assignments.

Algorithms↗
PubMed2006

Percutaneous needle aspiration, injection, and reaspiration with or without benzimidazole coverage for uncomplicated hepatic hydatid cysts.

BACKGROUND: Hepatic hydatid cyst is an important public health problem in parts of the world where dogs are used for cattle breeding. Management of uncomplicated hepatic hydatid cysts is currently surgical. However, the puncture, aspiration, injection, and re-aspiration (PAIR) method with or without benzimidazole coverage has appeared as an alternative to surgery over the past decade. OBJECTIVES: To assess the benefits and harms of PAIR with or without benzimidazole coverage for patients with uncomplicated hepatic hydatid cyst in comparison with sham/no intervention, surgery, or medical treatment. SEARCH STRATEGY: The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Controlled Trials Register in The Cochrane Library, MEDLINE, EMBASE, DARE, and ACP Journal Club and full text searches were combined (all searched October 2004). Reference lists of pertinent studies and other identified literature were scanned. Researchers in the field were contacted. SELECTION CRITERIA: Only randomised clinical trials using the PAIR method with or without benzimidazole coverage as the experimental treatment of uncomplicated hepatic hydatid cyst (ie, hepatic hydatid cysts which are not infected and do not have any communication with the biliary tree or other viscera) versus no intervention, sham puncture (ie, performing all steps for puncture, pretending that PAIR is being performed, but actually not performing the procedure proper), surgery, or chemotherapy were included. DATA COLLECTION AND ANALYSIS: Data were independently extracted and methodological quality of each trial was assessed by the authors. Principal authors of the trials were contacted to retrieve missing data. MAIN RESULTS: We found no randomised clinical trials comparing PAIR versus no or sham intervention. We identified only two randomised clinical trials, one comparing PAIR versus surgical treatment (n = 50) and the other comparing PAIR (with or without albendazole) versus albendazole alone (n = 30). Both trials were graded as 'adequate' for allocation concealment; however, generation of allocation sequence and blinding methods were 'unclear' in both of them. Compared to surgery, PAIR plus albendazole obtain similar cyst disappearance and mean cyst diameter with fewer adverse events (32% versus 84%, P < 0.001) and fewer days in hospital (mean + SD) ( 4.2 + 1.5 versus 12.7 + 6.5 days, P < 0.001). Compared to albendazole, PAIR with or without albendazole obtain significantly more often (P < 0.01) cyst reduction and symptomatic relief. AUTHORS' CONCLUSIONS: PAIR seems promising, but there is insufficient evidence to support or refute PAIR with or without benzimidazole coverage for treating patients with uncomplicated hepatic hydatid cyst. Further well-designed randomised clinical trials are necessary to address the topic.

Albendazole↗
PubMed2005

Missing forms and dropout in the TME quality of life substudy.

OBJECTIVE: Missing forms may pose problems in health related quality of life (QOL) studies, because the absence of a QOL measure may be related to the patient's health and hence to the patient's QOL itself. Studying patterns of missingness, dropout, and the possible impact of missing data on QOL measures is an important step in reporting outcomes of QOL studies. We study patterns of dropout and evaluate the impact of missing forms in the TME QOL substudy. METHODS: Patients with rectal cancer, randomized to receive either radiotherapy plus total mesorectal excision (TME) or TME only were included in the TME trial. QOL was evaluated in 1302 Dutch patients, before treatment, and 3, 6, 12, 18 and 24 months after surgery. Here only the visual analogue score (VAS) was studied. RESULTS: At baseline, differences between VAS scores were found with respect to whether the QOL forms were dated before or after radiotherapy and surgery. Differences were small between different statistical methods accounting for dropout; only a cross-sectional analysis gave biased results. CONCLUSION: The results of the sensitivity analysis indicated that a linear mixed model analysis is a reliable and attractive approach for this study.

Analysis of Variance↗