Data Collection Intervals Research Articles

The impact of antidepressant treatment on population health: synthesis of data from two national data sources in Canada

BackgroundIn randomized, controlled trials, antidepressant medications have been shown to reduce the duration of major depressive episodes and to reduce the frequency of relapse during long-term treatment. The epidemiological impact of antidepressant use on episode duration and relapse frequency, however, has not been described.MethodsData from two Canadian general health surveys were used in this analysis: the National Population Health Survey (NPHS) and the Canadian Community Health Survey (CCHS). The NPHS is a longitudinal study that collected data between 1994 and 2000. These longitudinal data allowed an approximation of episode incidence to be calculated. The cross-sectional CCHS allowed estimation of episode duration. The surveys used the same sampling frame and both incorporated a Short Form version of the Composite International Diagnostic Interview.ResultsEpisodes occurring in antidepressant users lasted longer than those in non-users. The apparent incidence of major depressive episodes among those taking antidepressants was higher than that among respondents not taking antidepressants. Changes in duration and incidence over the data collection interval were not observed.ConclusionsThe most probable explanation for these results is confounding by indication and/or severity: members of the general population who are taking antidepressants probably have more highly recurrent and more severe mood disorders. In part, this may have been due to the use of a brief predictive diagnostic interview, which may be prone to detection of sub-clinical cases. Whereas antidepressant use increased considerably over the data-collection period, differences in episode incidence and duration over time were not observed. This suggests that the impact of antidepressant medications on population health may have been less than expected.

Quantification of atrial tachyarrhythmia burden with an implantable pacemaker before and after pulmonary vein isolation.

Long-term efficacy of pulmonary vein (PV) ostial isolation for paroxysmal atrial fibrillation is difficult to assess. We evaluated the net duration of atrial tachyarrhythmia episodes (burden), atrial tachyarrhythmia episode frequency, and quality-of-life (QOL) before and after PV isolation in patients with an existing pacemaker featuring extensive diagnostic capabilities. Due to frequent recurrences of paroxysmal atrial fibrillation, PV isolation was performed 21 +/- 10 months following pacemaker implantation on 12 patients (57 +/- 5 years) with normal left ventricular function. Atrial tachyarrhythmia burden (ATB) and episode frequency were monitored daily by the device both pre- and postablation. QOL questionnaires were collected at ablation and 1, 3, and 6 months thereafter. Patients were followed for 20 +/- 9 and 11 +/- 9 months pre- and postablation, respectively. Membrane-active antiarrhythmic medications were discontinued after ablation in 8 of 12 patients. PV isolation resulted in a significant reduction of ATB from a median of 3.2 hours/day (preablation) to 0.2 hours/day (postablation, P < 0.01, Wilcoxon signed-rank test). The median tachyarrhythmia frequency was 6.4 episodes/day (preablation) and 0.3 episodes/day (postablation, P = 0.09). QOL measures significantly improved over the data collection intervals (P < 0.05). Tachyarrhythmia burden was positively associated with Symptom Checklist frequency and severity (P < 0.01). Significant long-term reductions in total ATB (symptomatic and asymptomatic) were observed. Furthermore, reductions in ATB were associated with improvements in QOL measures. Extensive monitoring capabilities in implantable devices help provide complete disclosure on the effect of PV isolation in paroxysmal atrial fibrillation patients.

Planning-Interval Duration in Labor-Shift Scheduling

This article proposes guidelines for managers and researchers regarding appropriate planning intervals in labor scheduling. This study distinguishes between planning intervals used for data collection and intervals used for scheduling employees. This distinction is relevant because it is not necessary for the two interval types to be of the same duration. The results of a simulation experiment show that both increased variability in the customer-arrival rate and high mean customer-arrival rates work to reduce the ideal length of both data-collection and schedule-development intervals. In fact, with a mean arrival rate of five customers per minute, the most profitable labor schedules originated with a five-minute data-collection interval combined with a five-minute schedule-development interval. At present, because of the paucity of procedures that can accommodate such brief intervals, managers will find fifteen-minute data-collection and schedule development intervals generally to be the most effective.

Obstructive sleep apnea, nocturia and polyuria in older adults.

The purpose of this study was to examine the relationship between nocturia and obstructive sleep apnea (OSA) in community dwelling older men and women. A repeated measures design was employed over a 24-hour period. The study was conducted in a clinical research center. Thirty community-dwelling elders (mean age=65.5, SD=8.4 years) with symptoms of nocturia and sleep disordered breathing, volunteered to participate. Both men (n = 13) and women (n = 17) and minority subjects (African-Americans, n = 19; Caucasian, n = 11) were included in the study. NA. Blood specimens were collected every 4 hours, except for an 8-hour collection period overnight. Urine specimens were collected ad libitum and at the end of each data collection interval. Urine and blood specimens were analyzed for ANP and AVP content. Polysomnography was conducted using a full 18-channel montage. Apnea was defined as a decrease in airflow of > or = 90% for a minimum of 10 seconds. Hypopnea was defined as > or = 30% decrease in airflow and desaturations required a > or = 3% decrease in oxygen saturation for a minimum of 10 seconds. The apnea hypopnea index (AHI) was calculated as the sum of apneas and hypopneas divided by hours of sleep. Twenty of the thirty subjects were found to have clinically diagnosable OSA (AHI > or = 5). AVP excretion was not correlated with changes in AHI levels. Conversely, total urine output, plasma ANP and urine ANP excretion were significantly higher among subjects with higher AHI levels (> 15). In subjects with elevated AHI (> 15), nighttime urine production and ANP excretion are elevated.

Sulphur By-Product: The Relationship between Volatile Sulphur Compounds and Dental Plaque-Induced Gingivitis

The purpose of this study was to evaluate the relationship between volatile sulphur compounds (VSC) and gingival health status, and to monitor the changes in VSC in early dental plaque-induced gingivitis. Using an experimental gingivitis model, twelve subjects between 19 and 28 years old, with a healthy gingival status, refrained from brushing and flossing one randomly selected half of the mandibular arch for two weeks. At baseline and during six subsequent appointments, gingival inflammation (GI), bleeding on probing (BOP), and sulfide levels (SUL) were measured using the Gingival Index and the Diamond Probe/Perio 2000 System. The Spearman correlation was used to compare the relationships between SUL, GI, and BOP on the brushing (B) and non-brushing (NB) sides. Data on the NB side revealed a stronger correlation than on the B side. Wilcoxon rank sum was used to evaluate the differences between mean SUL, GI, and BOP scores on the B and NB sides over time. Results indicate that SUL were the first periodontal parameter to show a significant difference between sides. SUL were significantly higher on the NB side at 4 of the 6 data collection intervals; therefore, SUL may be associated with the initiation and progression of early plaque-induced gingivitis.

The consistency of bisection judgments in visual grasp space.

We study whether bisection in visual grasp space (the region over which eye and hand can work together to grasp or touch objects) depends on fixation or on the method of judgment employed (the task). We determined observer bias and sensitivity for bisection judgments (in a fronto-parallel plane as well as along contours slanted in depth). Significant biases were found that varied across observers both qualitatively and quantitatively. These biases were stable for a given individual (across a year between data collection intervals) and across tasks (method of adjustment vs. forced-choice). When observers maintained fixation (on an endpoint or in the neighborhood of the bisection point), fixation location had a small but significant effect on bias, although those effects were small compared with bisection uncertainty. We conclude that bisection judgments differ significantly between fixations, but that the effect of fixation location on bisection is not large enough to be detected reliably by the observer moving his or her eyes during a judgment.

Duration of patency of laser-assisted tympanic membrane fenestration.

Laser-assisted tympanic membrane fenestration (LTMF) provides intermediate-duration middle ear ventilation, which benefits selected children with acute otitis media (AOM) and otitis media with effusion (OME). To evaluate clinical and technical factors that may affect duration of LTMF patency. Prospective clinical cohort effectiveness trial. Four tertiary care children's hospitals. Volunteer sample of 251 children (430 ears) followed up at 1, 2, 3, 4, 8, and 12 weeks; time to fenestration closure was evaluable in 201 ears, and assessment of cure at study conclusion was evaluable in 128 ears. Laser-assisted tympanic membrane fenestration for prospectively defined AOM or OME. The surgeon determined spot size, wattage, and concurrent adenoidectomy based on clinical judgment. Cure of AOM/OME with effusion at 90 days and duration of LTMF patency relative to spot size (1.8-2.8 mm), fenestration location on tympanic membrane, power (7-22 W), concurrent adenoidectomy, age, diagnosis (AOM vs OME), type of effusion, and preoperative tympanogram characteristics. Results are based on the number of ears that could be evaluated at each data collection interval. Fenestrations remained patent for 2 to 4 weeks (mean = 2.52, median = 2.0, SD = 1.4, n = 201); 97.4% were closed at 6-week follow-up. Spot sizes of 2.4 and 2.6 mm had a higher rate of patency than 2.0-mm spot size at 3 weeks following LTMF. Cure at 90 days was related to duration of patency for all patients combined and for patients treated for AOM and OME, but not for those undergoing adjunctive adenoidectomy. Cure at 90 days was related to larger spot size for all patients combined and those treated for AOM. Other investigated factors did not achieve statistical significance. Spot size of 2.4 mm or greater results in improved duration of LTMF patency, persisting for up to 3 weeks after LTMF, especially for treatment of AOM. Increased duration of LTMF patency correlates with greater incidence of cure of middle ear effusion at 90 days. Additional investigation is indicated to determine optimum spot size and optimum duration of patency for disease- severity-adjusted populations.

Longitudinal changes in children's speech and voice physiology after cochlear implantation.

The purposes of this investigation were 1) to describe speech/voice physiological characteristics of prelingually deafened children before and after cochlear implantation and determine whether they fall into a range that would be considered deviant, 2) to determine whether selected deviant articulatory and phonatory behaviors of children with cochlear implants persist despite long-term cochlear implant use and continued participation in aural rehabilitation services, and 3) to determine whether further development of deviant articulatory and phonatory behaviors occurs postimplantation. Seven prelingually deafened children who received cochlear implants after 5 yr of age were followed from shortly before implantation until 5 to 6 yr postimplantation. These children received their early education in a Total Communication environment and used the Nucleus 22-electrode cochlear implant. All of them initially used the MPEAK speech processing strategy, and five of them eventually upgraded to the SPEAK speech processing strategy. Speech/voice physiological measurements that were obtained periodically from the children included intraoral air pressure (P(o)), nasal and phonatory air flow, voice onset time (VOT), and fundamental frequency (F(o)). Data from the deaf children were compared with a database from 56 children with normal hearing to determine when the deaf children exhibited "deviant" speech/voice behaviors. Speech/voice behaviors were considered "deviant" if they never occurred for children with normal hearing or were associated with z-scores that were outside the range of +/-2.0. The deaf children showed a wide range of deviant speech and voice behaviors both pre- and post-cochlear implant. The most frequently occurring atypical behaviors were use of negative P(o), high P(o) for [b, m], long and short VOT for [p], and high F(o). Some deviant behaviors improved post-cochlear implant. However, deviant behaviors often persisted for several years post-cochlear implant. There was considerable evidence of further development of deviant behaviors post-cochlear implant. All of the deaf children demonstrated deviancy on at least two of our measures at the last data collection interval (5 to 6 yr post-cochlear implant). Children who received cochlear implants after 5 yr of age and who were educated in a Total Communication setting showed persistence and further development of deviant speech/voice behaviors for several years post-cochlear implant. Although our findings cannot be generalized to other populations of children with cochlear implants (i.e., those who were implanted earlier, those educated in auditory-oral programs), it seems wisest at the present time not to assume that children's deviant speech/voice behaviors will remit spontaneously with continued cochlear implant use. Our data provide an important comparative database for future investigations of pediatric cochlear implant users who have had shorter periods of auditory deprivation and who have received cochlear implants with more current technological features. Longitudinal Changes in Children's Speech and Voice Physiology after Cochlear Implantation

Improving the fit of bivariate smoothing splines when estimating longitudinal immunological and virological markers in HIV patients with individual antiretroviral treatment strategies.

CD4+ lymphocyte count and HIV RNA plasma viral load are longitudinally monitored in patients with HIV infection. Because data collection intervals may be unequally spaced and these markers experience high within-patient variability, they may be smoothed before use in subsequent models. Estimation strategies must be able to accommodate the drastic changes in viral load which may occur when an individual's treatment strategy is updated. Because these treatment changes are not regimented, these dynamics cannot be modelled using standard methods. We propose univariate and bivariate cubic smoothing splines to fit CD4+ count and viral load over time. The method is developed using state space equations, and the Kalman filter is used to calculate the log-likelihood. Non-linear optimization is used to obtain the maximum likelihood estimates. A modification of the Kalman filter allows non-informative or diffuse priors at the initial observation. Since treatment changes are expected to alter the shape of the curve, we further extend the Kalman filter to permit greater flexibility in the smoothing spline at these time points. The method produces smoothed estimates of the viral load and CD4+ count curves over time.

Process Evaluation Methods of a Peer-Delivered Health Promotion Program for African American Women

The Eat Well, Live Well (EWLW) Nutrition Program was a community-based, dietary change program delivered by peer educators to low-income African American women. To ensure that the program was delivered as intended, a process evaluation was conducted to determine the extent to which the content was accurate and comprehensive. The methodology included developing checklists for each of the intervention sessions, audiotaping randomly selected sessions, and independently rating the audiotapes. Overall comprehensiveness of the content delivered by the peer educators was 91.42%. Cohen’s kappa () for each data collection interval ranged from 0.95 to 0.97. Overall accuracy of information delivered was 88.52%. A process evaluation as described for the EWLW program is essential for peer-led health promotion programs and necessary to ensure program integrity. Practice implications are discussed.

Monthly variations in self-reports of alcohol consumption.

This study examines monthly variation in reports of recent alcohol consumption behavior. Telephone survey data collected by the Behavioral Risk Factor Surveillance System were used to measure self-reports of drinking and heavy episodic drinking in the 30 days before the interview. The sample (N = 57,758) comprised cases collected in six states in 5 selected years. Monthly variability in self-reported alcohol consumption was evaluated by logistic regression analysis, using "deviation from means coding" for the month of interview, with background variables and year of interview controlled and state-level clustering adjusted. Adults were significantly more likely to report past 30-day alcohol consumption when interviewed during the month of January and less likely to report consumption when interviewed during March. Respondents were also more likely to report heavy episodic drinking during the month of July. Despite large differences in alcohol consumption between male and female participants, these seasonal patterns were essentially the same for both genders. The findings suggest that assessments of alcohol consumption that do not consider seasonal variation may be biased. In order to minimize this bias, it is recommended that researchers avoid collecting data only during these particular times of the year or extend the data collection interval and control for seasonal variability.

Improving RUC-1 Wind Estimates by Incorporating Near-Real-Time Aircraft Reports

Abstract A verification study of wind accuracy is presented for wind nowcasts generated by augmenting Rapid Update Cycle (RUC) wind forecasts with near-real-time aircraft reports using the Integrated Terminal Weather System (ITWS) gridded winds algorithm. Aircraft wind reports collected between the end of the RUC data collection interval and the time each RUC forecasts is valid are available for use in augmenting the RUC wind forecast to form a wind nowcast. The 60-km resolution, hourly RUC-1 wind forecasts are used. ITWS-based nowcast wind errors and RUC forecast wind errors are examined statistically over a 1-yr dataset. The addition of the recent aircraft reports significantly reduces the rms vector error and the 90th percentile vector error. Also reduced is the number of hours of sustained large errors and the correlation among errors. The errors increase with increasing wind speed, in part due to an underestimation of wind speed that increases with increasing wind speed. The errors in the augmented w...

Development of a Low-Cost Tide Gauge

Abstract A low-cost tide gauge was developed and field tested to demonstrate a technology that would enable more cost-effective and greater sampling of spatially variable water levels and ocean surface waves. The gauge was designed to be adaptable to expendable and, possibly, air-deployed use for applications such as support of naval operations. The gauge incorporates a single printed circuit board that includes a very low power 3.3-Vdc microprocessor and 1 Mbyte of nonvolatile flash memory. A low-cost solid-state pressure sensor provides pressure data that are corrected automatically as a function of measured pressure and temperature and are processed within the gauge to provide low-frequency water levels and nondirectional surface wave information. Gauge-operating lifetimes range from more than four months to more than two years, depending on the data collection mode (tide or tide–wave) and the data collection interval (half-hourly or hourly). Gauge measurements are compared to measurements from a Sea-B...

Insertion time of the pulmonary artery catheter in critically ill patients.

Measurement of the time elapsed from the decision to use a pulmonary artery catheter to the onset of the adapted treatment. Prospective study. Critical care unit of a university hospital. A total of 104 critically ill patients. The time elapsed from the decision to use a pulmonary artery catheter to the onset of the adapted treatment. Five time intervals (availability, preparation, catheterization, data collection, and therapeutic intervals) were individualized according to the times of decision of pulmonary artery catheter insertion, operator's hand washing, venipuncture, postoperative dressing, data collection, and the effective onset of subsequent therapy. Among 120 used pulmonary artery catheters, seven could not be inserted. The time to use the pulmonary artery catheter was never shorter than 45 mins (median value = 120 mins). For availability, preparation, catheterization, data collection, and therapeutic intervals, the median values were 30, 20, 20, 20, and 10 mins, respectively. The availability and data collection intervals were shortened during the night period and the fourth quarter of the study, respectively. The pulmonary artery catheter use is time consuming. However, the availability and data collection intervals could be shortened.

Pavement Distress Under Accelerated Trafficking

A test pad was closely monitored for a 6-month period, with 640,000 axle load repetitions applied to the test pavement. The load was applied by the Texas Mobile Load Simulator, a full-scale accelerated loading device. Pavement performance data, such as rutting and cracking, were collected at intervals of 0; 2,500; 5,000; 10,000; 20,000; 40,000; 80,000; 160,000; 320,000; and 640,000 axle repetitions. Falling weight deflectometer (FWD) tests were performed at these same data collection intervals to characterize the structural capacity of the pavement system. Although there is a trend indicating that locations with higher FWD deflection result in higher rutting, a unique relation to predict rutting accurately from the surface deflection alone was not found in the study. The back-calculated asphalt concrete pavement moduli were reduced by 50 percent of the original value at the end of 320,000 repetitions. However, the test was not terminated until 640,000 repetitions, when moduli were reduced to 40 percent of the original values. Both FWD deflection and percent of cracked area share the same trend; the left wheelpath had higher initial FWD deflections and later yielded a higher percentage of cracked area. Approximately 50 percent of the wheelpath area was cracked at the end of 80,000 repetitions, as measured by counting the number of cracked squares on a 100 mm by 100 mm grid. However, most of the cracks were hairline cracks. The percentage of cracked area is strongly related to the grid size used. A grid size of 100 mm by 100 mm has been recommended by other researchers and was adopted in this study. Eighty-five percent and 90 percent of the area in the wheelpaths was cracked at the end of 320,000 and 640,000 repetitions, respectively. These numbers are higher than those adopted by the Asphalt Institute, which defines failure as 45 percent cracking in the wheelpath.

Implications of chaos research for new product forecasting

The mathematics of chaotic dynamics are now familiar to product forecasters and marketing researchers. Do possible sightings of chaos in new product data sets have implications for the way new product studies and launches should be performed? Should these practices be affected by the knowledge that chaos is possible in principle? Although the mathematics of new product diffusion models clearly allow for chaotic bifurcations and fluctuations, these phenomena have not been reliably observed for actual products. In this article we offer reasons why this has been so. The reasons include measurement and specification error, and aggregation and data collection interval effects. We conclude that marketers have not been looking in the right places to find chaos (or at least traditional market research reports do not lend themselves to an effective search for chaos). and that brand managers behave in a way that minimizes chances of observing chaos. The exploration of chaos in the context of new product management leads to an analysis of the implications of chaos for the practice of new product forecasting.

Mass dependence of time-lag focusing in time-of-flight mass spectrometry—an analysis

When using mass spectral detection strategies in which wide ranges of m/z values are monitored, it is important for ions of all masses of interest to be in focus during the data collection interval. In conventional time-of-flight mass spectrometry of gaseous samples using dual field source extraction for spatial compensation, ion focus is a function of the time lag and the mass-to-charge ratio of the ion. The mass dependence of ion focus in a CVC 2000 time-of-flight mass spectrometer has been studied using a computer simulation in order to determine the mass ranges over which the losses in mass resolution and peak intensity are acceptable. As few as three different values of time lag are required to cover the m/z range from 50 to 700 u. Selection of optimum extraction voltages involves a trade-off between the width of the mass windows for any given time lag setting and the total mass range available with unit-mass-resolution.

Strategic Planning Tool for GPS Surveys

Accuracy of a GPS baseline determination is a complex function of satellites selected and the duration and timing of the data collection interval. Satellite selection can be extremely important if the GPS receiver employed is one that tracks only four satellites simultaneously. Even with receivers that track all visible satellites, the timing and duration of the data collection interval can be significant. For short data collection intervals and short baseline observations, an order of magnitude difference in accuracy may result, depending on whether or not the whole cycle ambiguity can be resolved. The ability to resolve whole cycle ambiguities is in turn determined by which satellites are selected and the timing and duration of the tracking interval. Magnavox has developed a “Differential GDOP” program that provides a measure of the ability to resolve whole cycle ambiguities as a function of these parameters. This paper describes a method and rationale for “Differential GDOP” computations. A practical example is used to illustrate its benefits in generating a data collection strategy.

An interactive video-computer tracking system for quantification of locomotor behavior

We have developed a flexible, moderately priced, behavioral analysis system which has been used to determine the response of salmonids to certain olfactory stimulants. The system, which we call ITS for interactive computer-video tracking system, consists of a 128K Apple IIe computer with software, a video camera and videocassette recorder, and a special-effects generator. Experiments are video taped and then, during playback, the special effects generator is used to simultaneously display the video image and the graphics output of the computer on a monitor. The user tracks the animal of interest using an electronic pen, and the position of that animal in the test chamber, in the form ofx-y coordinates, is determined by the computer at user-defined time intervals. When tracking is complete, a plot of the track of the animal is printed within the outline of the test chamber. The following data can also be calculated: swimming velocity, distance from a predetermined point in the chamber (for example, olfactory stimulant source), and time spent in a given area. These variables can be calculated over any chosen time periods and/or for the entire experiment. ITS has numerous advantages over commercially available devices that perform similar tasks. First, it is relatively inexpensive, especially if one already owns video equipment and a computer. Second, it can analyze many types of experiments that can be stored on video tape, including field observations or manipulations. Third, because it is not automated, it is easy to track multiple objects, even if their tracks cross or are not easily located against a low-contrast background. Finally, because whole images do not have to be digitized, and data collection intervals can be adjusted by the user, it is possible to analyze very long experiments with a microcomputer. In this paper we describe ITS and then we demonstrate how we have used it to demonstrate that changes in ambient pH alter the behavioral response of juvenile Atlantic salmon to olfactory stimuli.

Automated mapping of the ocean floor using the theory of intrinsic random functions of order k

High-quality contour maps can be computer drawn from single track echo-sounding data by combining Universal Kriging and the theory of intrinsic random function of order K (IRFK). These methods interpolate values among the closely spaced points that lie along relatively widely spaced lines. The technique provides a variance which can be contoured as a quantitative measure of map precision. The technique can be used to evaluate alternative survey trackline configurations and data collection intervals, and can be applied to other types of oceanographic data.