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PubMed1998

Qualitative interaction between the observer and the observed in veterinary epidemiology.

The phenomenon of qualitative interaction between the research activity and the studied object exists in veterinary epidemiology, as in all observation-based disciplines. Observational studies carried out under farm conditions strongly involve the farmers and the farm's usual advisors in the data collection. This leads to various biological and sociological interactions between the observer and the observed that can modify the results of the study. Some methodological considerations are proposed in order to consider such qualitative interaction, from the designing of the study through to the interpretation of the results. Examples are presented to illustrate these ideas.

Animal Diseases↗
PubMed2003

The role of observational data in monitoring trends in antiretroviral treatment and HIV disease stage: results from the Australian HIV observational database.

OBJECTIVES: To illustrate how human immunodeficiency virus (HIV) observational databases may be used to monitor trends in HIV treatment and HIV disease outcomes through data reported from the Australian HIV Observational Database (AHOD). METHODS: Time trends in the use of antiretroviral treatment, and changes in treatment strategies were calculated in patients recruited to AHOD from HIV specialist clinics including hospitals, sexual health clinics and general practices. These results were then compared to trends reported from other observational cohorts. RESULTS: By September 2001, 1961 patients were recruited to AHOD. Since entering AHOD, 3% of patients have been diagnosed with an AIDS defining illness, and 2% of patients have died, of which, 54% were non-HIV related deaths. The proportion of patients receiving antiretroviral therapy increased from 66% between January and June 1998 and 77% between July and September 2001. The most commonly received treatment regimen was triple therapy including a protease inhibitor (PI), ranging between 36% in January and June 1998 and 31% in July to September 2001. Triple therapy including a non-nucleoside reverse transcriptase inhibitor (NNRTI) more than doubled to 32% between July and September 2001. The proportion of patients receiving either stavudine (d4T) or zidovudine (AZT) treatment regimens decreased from 92% between January and June 1998 to 76% between July and September 2001. Patients receiving ritonavir in combination with another PI increased, as did the proportion of patients interrupting therapy for more than 3 months. CONCLUSION: These findings suggest there have been changes in the way antiretroviral treatments have been used in Australia, and are consistent with the current literature. Furthermore, these findings demonstrate the usefulness of observational cohorts as a surveillance tool monitoring trends in treatment and disease progression.

Anti-HIV Agents↗
PubMed2002

Intra-observer and inter-observer repeatability of anterior eye segment analysis system (EAS-1000) in anterior chamber configuration.

BACKGROUND: Anterior chamber configuration can be assessed via optical or ultrasonic techniques. Scheimpflug photography is a non-invasive method measuring the anterior segment. The Anterior Eye Segment analysis system, EAS-1000, utilises the Scheimpflug principle and was found to have good repeatability. Previous repeatability studies, however, have had limitations in their design. The current study investigated the intra-observer and interobserver repeatability of the EAS-1000. METHODS: Twenty-five healthy young subjects were recruited. The anterior chamber angles in different quadrants were measured by two examiners for interobserver analysis. The first examiner repeated the measurement at another session for intra-observer analysis. The 95% limits of agreement and intra-class correlation coefficient (ICC) were calculated. The anterior chamber depth was also measured and compared with ultrasound biometry. RESULTS: The anterior chamber angle assessment demonstrated good intra-observer (ICC ranging from 0.77 to 0.90 for different quadrants) and interobserver (ICC ranging from 0.68 to 0.81 for different quadrants) repeatability. The 95% intra-observer limits of agreement were within +/-5 degrees. The 95% interobserver limits of agreement were within +/-6 degrees. There was no significant difference between male and female subjects or among angles at different quadrants. The anterior chamber depth was found to be repeatable (ICC > 0.90) with 95% limits of agreement +/-0.1 mm. The anterior chamber depth was shallower than that obtained from ultrasound biometry. CONCLUSIONS: The EAS-100 is a non-invasive instrument which is repeatable for measuring the anterior chamber angle and depth. It provides quick results and is good for screening purposes. There is an under-estimation of anterior chamber depth, as previously reported.

Adolescent↗
PubMed2002

Impact of observers' experience and training on reliability of observations for a manual handling task.

Observation reliability (agreement percentage and kappa coefficients) for six experienced ergonomists and six untrained participants was computed. Participants were first tested after a training session and 1 week later after an additional practice session. Two formats were used: free practice and directed exercise. Reliability was tested for 17 variables and 20 sequences using photographic and video supports. The participants were asked to indicate whether they were confident about their answer, to rate this confidence on a scale of 1 to 10, and when the confidence rating was below 8, to provide a reason for this. Experience and additional practices had no clear impact on reliability, which was excellent overall. The main reason given was that the event to be observed took place at the borderline between two classes. The observers' rating on the scale appeared to be tied to the subsequent reliability computed. The use of a confidence scale appeared to be a useful tool for forecasting observation problems.

Adult↗
PubMed2003

Reliability of radionuclide gastroesophageal reflux studies using visual and time-activity curve analysis: inter-observer and intra-observer variation and description of minimum detectable reflux.

Radionuclide studies have gained wide acceptance in the evaluation of infants and children with gastroesophageal reflux (GER). For correct interpretation of scan results, knowledge of inter-observer and intra-observer variability and minimum detectable reflux volume is essential. In this study, we evaluated the methodological issues underlying the visual assessment of GER and time activity curve analysis. An in vitro model of stomach and oesophagus was established to determine the minimum detectable reflux by placing various volumes and concentrations representing the diluted activity in the stomach. In the clinical part 99 patients were imaged for 1 h after oral administration of 99mTc sulfur colloid. Eleven patients were excluded from the study either due to incomplete clinical data or suboptimal image quality. Frames of 16 s each, and time-activity curves which were generated after drawing regions of interest from the oesophagus, were read three times by an experienced nuclear medicine physician and a resident in training. On the phantom study, the concentration, volume and duration were the determining factor for the visualization of reflux. In the clinical part, the overall incidence of GER in 88 patients was 69%. The mean intra- and inter-observer reproducibility (kappa values) was 0.76 and 0.7065, respectively. Agreement was slightly higher in the analysis of time-activity curves (0.767 and 0.731). Our results indicate that GER may be reproducibly analysed on scintigraphy by the same and different observers with varying levels of training. Its visualization is associated with reflux duration, volume and dilution factor of radioactivity.

Child↗
PubMed2001

Treatment of tuberculosis in a rural area of Haiti: directly observed and non-observed regimens. The experience of H pital Albert Schweitzer.

SETTING: Artibonite Valley, a rural area in Haiti. OBJECTIVE: To evaluate a tuberculosis control program in rural Haiti and to compare two strategies for treatment implemented in two areas that were not chosen at random: treatment delivered at the patients' homes observed by former tuberculosis patients (DOT), and non observed treatment (non-DOT). DESIGN: Retrospective analysis of the clinical records of adult patients diagnosed with tuberculosis at H pital Albert Schweitzer in Deschapelles, Haiti, during 1994-1995. RESULTS: There were 143 patients in the non-DOT group and 138 patients in the DOT group. The results of treatment were significantly different: in the non-DOT group 29% defaulted, 12% died and 58% had a successful outcome; in the DOT group 7% defaulted (P < 0.01), 4% died (P = 0.01) and 87% had a successful outcome (P < 0.01). These differences are also significant when considering only human immunodeficiency virus (HIV) infected patients (defaulted P < 0.01; died P = 0.09; successful outcome P < 0.01). CONCLUSION: Delivering treatment in patients' homes with direct observation by former tuberculosis patients can achieve good results, even in an area of extreme poverty and high rates of HIV infection. In this population the number of patients who are able to complete their treatment without observed administration is far from optimal.

Adult↗
PubMed1996

The actor-observer effect revisited: effects of individual differences and repeated social interactions on actor and observer attributions.

This research examined several factors hypothesized to influence the actor-observer effect (AOE). Participants engaged in 3 successive dyadic interactions: after each interaction, they rated the importance of 4 causal factors in influencing their behavior and that of their partner. The AOE held for 1 external factor, interaction partner, and 1 internal factor, personality, but not for situation or mood. Actor and observer attributions changed in predicted ways across the 3 interactions: Actors increasingly emphasized the importance of their partner, whereas observers increasingly emphasized personality: both actors and observers substantially lowered their attributions to the situation. We found consistent individual differences in attributional tendencies that allowed us to predict who showed the AOE. Together, the findings demonstrate that A-O differences depend on: (a) the specific causal factor invoked, (b) the individual's history in the situation, and (c) individual differences among attributors. Discussion focuses on the limited generality of the AOE and the need for a more complex formulation of A-O differences in attribution.

Adolescent↗
PubMed1999

Assessment of practicing family physicians: comparison of observation in a multiple-station examination using standardized patients with observation of consultations in daily practice.

PURPOSE: Looking for a valid, reliable, and feasible method to collect data on the performances of practicing family physicians, the authors compare the measurement characteristics of a multiple-station examination (MSE) using standardized patients with those of a video assessment of regular consultations in daily practice (practice video assessment, PVA). METHOD: In a cross-sectional study, consultations of 90 family physicians were videotaped both in an MSE and in their daily practices. Peer-observers used a validated instrument (MAAS-Global) to assess the physicians' communication with patients and their medical performances. The physicians were randomly divided into two groups, comparable for demographic characteristics, and half underwent the assessments in reverse order to test for time-order effects. Content validity, criterion validity, reliability, and feasibility of the two methods were compared. RESULTS: Content validity of the PVA was superior to that of the MSE, since the domain of general family practice care was better covered. Observed participants judged the videotaped practice consultations to be "natural," whereas hardly any family physician, after reviewing the videotaped consultations of the MSE, recognized his or her usual working style. Specific criteria made it possible to standardize real practice. Concerning criterion validity, only the medical-performance components of the two methods correlated. No correlation was found for the communication components. Real-practice performance proved to be less influenced by observation than was performance during the MSE. The reliabilities of the two methods, expected to be better in the controlled MSE, were comparable. The administration of the PVA was more flexible, less costly, and better accepted by the family physicians than was that of the MSE. CONCLUSION: Assessment for quality improvement of family physicians' practices by video observation in daily practice is superior to video assessment in a simulated setting using standardized patients.

Adult↗
PubMed2002

Fractionated stereotactic radiotherapy for the treatment of optic nerve sheath meningiomas: preliminary observations of 33 optic nerves in 30 patients with historical comparison to observation with or without prior surgery.

OBJECTIVE: We investigated the safety and efficacy of stereotactic radiotherapy as an alternative therapy to surgical resection for optic nerve sheath meningiomas (ONSMs). METHODS: Thirty patients and 33 optic nerves with ONSMs were treated with conventional fractionated stereotactic radiotherapy treatment (CF-SRT) between July 1996 and May 2001 with the use of a 6-MeV LINAC designed for and dedicated to radiosurgery. The LINAC technique involved daily CF-SRT involving a relocatable frame, an average of three isocenters, and high-radiation dose conformality established by noncoplanar arc beam shaping and differential beam weighting. The patients who were treated with CF-SRT were followed clinically with serial visual fields and radiographically with both magnetic resonance imaging and functional (111)In-octreotide single-photon emission computed tomography. The results of treatment were compared with a historical control group of ONSM patients who were either observed or treated surgically and then observed. RESULTS: Our study population comprised 18 women and 12 men with a median age of 44 years (age range, 20-76 yr). The median isosurface radiation dose was 51 Gy (dose range, 50-54.0 Gy), and the median clinical follow-up time was 89 weeks (range, 9-284 wk). Of 22 optic nerves with vision before CF-SRT, 20 nerves (92%) demonstrated preserved vision, and 42% manifested improvement in visual acuity and/or visual field at follow-up. Comparison of our patients with a historical control group revealed preserved vision in only 16% of patients in a comparable period of observation, along with a 150% greater probability of visual improvement. Four patients (13%) had posttreatment morbidities, including visual loss (two patients), optic neuritis (one patient), and transient orbital pain (one patient). On magnetic resonance imaging studies, there was no evidence of tumor progression or recurrence in all patients, including tumor volume reductions noted in four patients. All six patients monitored with (111)In-octreotide scintigraphy demonstrated significant decreases in tumor activity after CF-SRT. CONCLUSION: To date, this article describes the largest reported series of ONSMs. Although longer follow-up is necessary, we think that CF-SRT represents a safe alternative to surgery and offers a higher likelihood of preserved or improved vision in patients with ONSM. Our analysis suggests that CF-SRT is also preferable to observation. Functional (111)In-octreotide single-photon emission computed tomographic scintigraphy provides a useful technique for the assessment of tumor control that complements serial posttreatment magnetic resonance imaging in patients with ONSMs.

Adult↗
PubMed1977

Observer agreement, credibility, and judgment: some considerations in presenting observer agreement data.

Graphical and statistical indices employed to represent observer agreement in interval recording are described as "judgmental aids", stimuli to which the researcher and scientific community must respond when viewing observer agreement data. The advantages and limitations of plotting calibrating observer agreement data and reporting conventional statistical aids are discussed in the context of their utility for researchers and research consumers of applied behavior analysis. It is argued that plotting calibrating observer data is a useful supplement to statistical aids for researchers but is of only limited utility for research consumers. Alternatives to conventional per cent agreement statistics for research consumers include reporting special agreement estimates (e.g., per cent occurrence agreement and nonoccurrence agreement) and correlational statistics (e.g., Kappa and Phi).

Journal Article↗
PubMed1990

Dietary intake and observed activity of stunted and non-stunted children in Kingston, Jamaica. Part II: Observed activity.

It is generally believed that activity levels are reduced in poorly nourished children. This may conserve energy, but may have a detrimental effect on mental development. However there are few data which support this hypothesis. No previous studies were found which looked at the activity levels of stunted children. In this study we modified the time and motion observation methods of Torun (1984) by using recording periods of 1 instead of 10 min. This significantly reduced the estimated time spent by young children in moderate and vigorous activities. Four hours of observing young children while they were awake, using the modified method, produced highly reliable data. The activity levels of a subsample of children described in part I were observed. The children were aged 12-24 months and were observed for 4 h on 2 d. Seventy-eight stunted children (height less than -2 SD of median, NCHS) were compared with 26 non-stunted children (height greater than -1 SD). The stunted children were significantly less active than the non-stunted children, although the difference in activity rating was small (3.4 per cent). They spent more time in light activities (P less than 0.001) and less time in moderate or vigorous activities (P less than 0.01). Both groups slept a similar amount. Using Torun's values for the energy cost of activities it appears unlikely that the reduced activity would conserve energy to a great extent, but it may still be of biological importance, since it is comparable to the energy cost of growth at this age. Activity levels increased with age but were not significantly related to weight for height.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1986

Destruction of rat mammary tumor and normal tissue microcirculation by hematoporphyrin derivative photoradiation observed in vivo in sandwich observation chambers.

The effect of hematoporphyrin derivative photoradiation on tumor and normal tissue microcirculation was studied microscopically in vivo on rats with mammary carcinomas transplanted into subcutis in transparent observation chambers. One day after i.p. injection of hematoporphyrin derivative (15 mg/kg), chambers were exposed to red light (632 +/- 2 nm, eight light dose values, 0 to 270 J/cm2). After an initial blanching (ischemia) of the tumor accompanied by apparent vasoconstriction, reperfusion was observed with a slowing down of the tumor circulation, vasodilatation, and eventually a complete stasis, together with diffuse hemorrhages and subsequent necrosis. Besides, in large normal tissue vessels, platelet aggregates were observed, but no hemorrhage. Tumor regrowth occurred unless the tumor circulation and the adjacent normal tissue circulation were both destroyed. Tumor cell viability after treatment was assessed by transplanting the tumor from the chamber into the flank of the same animal. Even after a combined porphyrin and light dose 4 times the lethal dose for all tissues in the chamber, five of five transplanted tumors did regrow. This leads to the conclusion that, in our model system, tumor cell death after photoradiation occurs secondary to destruction of the microcirculation. In order to obtain additional information on normal tissue damage, rat ears were also irradiated. For the same light dose, the biological effect was only slightly larger than that of the normal tissue in the observation chambers, even though the measured ratio of porphyrin concentrations in ears and normal tissue in the chambers (subcutis) was about six.

Animals↗
PubMed1993

Observations on structural features and characteristics of biological apatite crystals. 5. Three-dimensional observation on ultrastructure of human enamel crystals.

In a series of studies to investigate the structural features of the biological crystals, such as the tooth and bone, using an electron microscope, we examined the ultrastructure of the enamel, dentin, and bone crystals at near atomic resolution and showed the configuration of the hydroxyapatite structure through the cross and longitudinal sections of the crystals. Thereafter, based on the results of the observations by the authors of the ultrastructure of the tooth and bone crystals, thinking that it might be possible to conduct direct three-dimensional observation of the configuration composing the unit cell of the hydroxyapatite crystals, we conducted a study on this. These results indicated that it was possible to sterically observe the configuration of the hydroxyapatite structure composing the enamel crystal. The materials used for this study were the middle layer of the noncarious enamel from the freshly extracted human erupted permanent molars. The small cubes of the enamel were fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin using the routine methods. The ultrathin sections were cut with a diamond knife without decalcification and were examined with the HITACHI H-9000 H type transmission electron microscope operated at 300 kV. Each crystal was observed at an initial magnification of 500,000 times and at the final magnification of 10,000,000 times and over. We sincerely believe that the electron micrographs shown in this report are the first to show three-dimensionally the configuration of the hydroxyapatite structure composing the crystal in the cross and longitudinal sections of an enamel crystal.

Dental Enamel↗
PubMed2003

Last observation carry-forward and last observation analysis.

Drop-out often occurs in clinical trials with multiple visits and drop-out is often informative in the sense that the population of patients who dropped out is different from the population of patients who completed the study. To handle data with informative drop-out, an intention-to-treat analysis, which evaluates treatment effects over the population of all randomized patients with at least one post-treatment evaluation, is often required by the regulatory agencies. As a popular and simple intention-to-treat analysis, the last observation carry-forward (LOCF) analysis of variance (ANOVA) performs a statistical test for treatment effects by treating the last observation prior to drop-out as the observation from the last visit. Although discussions, examples and limited empirical results about the LOCF analysis can be found, its theoretical property is unclear. We find that the LOCF one-way ANOVA test is actually asymptotically valid (that is, its asymptotic size is equal to the nominal size) in the special but important case where only two treatments are compared and the two treatment groups have the same number of patients, regardless of whether drop-out is informative or not. In other cases, however, the asymptotic size of the LOCF test is different from the nominal size and is often too small when drop-out is informative, which results in a loss in power of detecting treatment effects, a disadvantage to drug companies. We propose an asymptotically valid test for comparing the global means over subpopulations, where each subpopulation contains patients dropping out after a particular visit. Some simulation results are presented to study the finite sample performance of the LOCF test and our proposed test.

Analysis of Variance↗
PubMed1992

Inter-observer and intra-observer variability of mammogram interpretation: a field study.

To evaluate the performance of radiologists in mammographic mass screening, seven radiologists read blindly the mammograms of 45 women (two views for each breast). The films included 12 normal, 24 benign disease and 9 cancers. The readings were repeated after 2 years. As expected, variability was higher among radiologists than between the two readings of the same radiologist, but general reproducibility was moderate. Kappa values for a positive/negative classification were 0.45 at the first and 0.44 at the second reading (inter-observer comparisons). For the intra-observer comparisons, Kappa values ranged from 0.35 to 0.67 (mean 0.56). Generally, accuracy was low partly due to the difficulty of the cases. A slight increase in sensitivity was observed at the second reading. The level of agreement is a good indicator of accuracy. Proper training and standardization of criteria are essential before mass breast screening is implemented.

Breast Diseases↗
PubMed2004

Inter-observer and intra-observer reliability of a sleep questionnaire in Indian population.

UNLABELLED: Sleep disorders are a cause of significant morbidity and mortality. These are however still not widely detected/treated. Though various questionnaires have been designed for screening purposes, none are available in India. AIM: To construct a questionnaire for detection of sleep disorders and determine its reliability and validity. MATERIAL AND METHOD: The questionnaire was prepared from the Case Western Health Research Questionnaire, translated into Hindi and then back into English, prior to its use. This was administered to 20 subjects at an interval of 2 weeks by the same observer to determine the intra-observer reliability. For estimation of validity, 275 subjects were evaluated by a trained health worker and a specialist in sleep disorders. The specialist's opinion was taken as the 'gold standard' to calculate sensitivity and specificity. RESULTS: The kappa statistic was 0.94 for intra-observer reliability. The sensitivity and specificity were calculated for the question, presence/absence of sleep disorders and for all the other questions also. The sensitivity ranged from 70-91% and specificity 80-100%. CONCLUSION: This questionnaire is simple to use, reliable and has good sensitivity and specificity. It can be used in epidemiological community surveys.

Adult↗
PubMed1993

Abnormalities of the neonatal ear: otoscopic observations, histologic observations, and a model for contamination of the middle ear by cellular contents of amniotic fluid.

It is unknown whether childhood ear disease could be present long before symptoms provoke an initial otoscopic examination. A newborn middle ear might or might not start in a pristine, privileged state. The clinician evaluating later infant and childhood ear disease is often unaware of the status of a patient's ear from the neonatal period, the earliest time at which the tympanic membrane can be evaluated. Adding to the physician's handicap, normative otoscopic and histologic data on the neonatal ear are incomplete. In order to test the hypothesis that disease in the neonatal middle ear may be more common than is generally appreciated, the population of critically ill neonates was selected for study since this group can provide both clinical as well as histologic data. This manuscript is divided into three parts. Clinically, otoscopic observations were analyzed on infants in an intensive care unit. Histologically, neonatal temporal bones were studied for normal anatomy and pathology of the middle ear and antrum. Experimentally, an animal study was performed to evaluate the potential effect of amniotic fluid cellular contents aspirated into the middle ear. I. Clinical Otoscopic Observations. Daily otoscopic examination was conducted on 44 neonates in an intensive care unit. Specific parameters of the otoscopic examination were evaluated to compare with the normal, translucent tympanic membrane of the older child. The otoscopic appearance was found to be abnormal in 97.7% of neonatal ears. Of the otoscopic parameters evaluated, right ears averaged 2.6 abnormalities and left ears averaged 2.5 otoscopic abnormalities. The otoscopic appearance of the neonate in the neonatal intensive care unit is nearly universally abnormal. II. Temporal Bone Histologic Observations. One hundred eleven temporal bones from 56 neonates were collected for histologic study by light microscopy. Mesenchyme filling more than 60% of the middle ear space was found in 13 bones. Amniotic fluid cellular content was detected in 90 bones. Purulent otitis media was detected in 24 bones. Varying amounts of blood were found in the middle ear space of 34 bones. Only 7 of the bones had no significant middle ear abnormality. It is concluded that in the critically ill neonate, the middle ear and antrum usually contain cellular or fluid material, often in significant volume, that would not be considered normal in the older patient. III. An Animal Model Simulating Contamination of the Middle Ear by Cellular Contents of Amniotic Fluid.(ABSTRACT TRUNCATED AT 400 WORDS)

Amniotic Fluid↗
PubMed1989

Central station data displays: an experimental evaluation of observer performance. Part 1: Number of displays and observation time.

16 experienced ICU nurses monitored simulated central station VDU displays for the occurrence of ectopic beats and for signs of deterioration in general cardiovascular status. Each period of monitoring lasted for 1 h, and on separate occasions each nurse monitored 1, 2, 4 or 6 displays simultaneously. As the number of observed screens increased, performance declined significantly, with reduced identifications of discrete events (e.g., ectopic beat detections), and with increased delays in determining a deterioration in cardiovascular status; in addition, a secondary task was less accurately and efficiently performed, and the nurses tended to become increasingly fatigued. Efficient observing was maintained over the 1 h monitoring period, but only at considerable cost in terms of fatigue and a loss of alertness. The results suggest that there may be restrictions in the use of complex central station facilities at first-line observation posts for patient care.

Cardiac Complexes, Premature↗