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The Test-Retest Reliability of the Photopic Negative Response (PhNR).

ABSTRACT: The photopic negative response (PhNR) may be useful as a tool to monitor longitudinal change in retinal ganglion cell (RGC) function. The goal was to assess PhNR test-retest reliability, and to estimate the amount of change between tests that is likely to be statistically significant for an individual test subject.Photopic electroretinograms (ERGs) were recorded from 49 visually normal subjects (mean age, 38.9 years; range, 21-72 years). Signals were acquired using Dawson-Trick-Litzkow (DTL) electrodes in response to red stimulus at four flash energies (0.5, 1, 2.25, 3 cd·s/m(2)) on a blue background (10 cd/m(2)). The PhNR amplitude was recorded from prestimulus baseline to trough (BT), prestimulus baseline to fixed time point (BF), and b-wave peak to trough (PT). The ratio of baseline PhNR to b-wave amplitude (BT/b-wave) was calculated. Reliability was assessed using the intraclass correlation coefficient (ICC2,1) and coefficient of repeatability (CoR).Flash energy of 1.00 cd·s/m(2) produced reliable, well-defined traces. At this stimulus, the a- and b-wave amplitudes were reproduced with moderate reliability (ICC, 0.62; CoR%, 90.0%; and ICC, 0.74; CoR%, 54.3%; respectively). For PhNR, the order from most to least reliable measurement was: PT (ICC, 0.64; CoR%, 59.1%), BT (ICC, 0.40; CoR%, 148.3%), and BF (ICC, 0.22; CoR%, 166.1%). The BT/b-wave did not improve reliability (ICC, 0.37; CoR%, 181.5).The b-wave peak-to-PhNR trough amplitude produced the most reliable measurement.A relatively large magnitude of change in PhNR amplitude is required to make clinical inferences about changes in RGC function. Refinement to the technique of acquisition and/or processing of the PhNR is recommended to improve reliability.

SUBMITTER: Tang J

PROVIDER: S-EPMC4219366 | biostudies-other | 2014 Oct

REPOSITORIES: biostudies-other

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Project description:BackgroundNeurocognitive testing is an important concussion evaluation tool, but for neurocognitive tests to be useful, their psychometric properties must be well established. Test-retest reliability of computerized neurocognitive tests can influence their clinical utility. The reliability for a commonly used computerized neurocognitive test, CNS Vital Signs, is not well established. The purpose of this study was to examine test-retest reliability and reliable change indices for CNS Vital Signs in a healthy, physically active college population.HypothesisCNS Vital Signs yields acceptable test-retest reliability, with greater reliability between the second and third test administration compared with between the first and second administration.Study designCohort study.Level of evidenceLevel 3.MethodsForty healthy, active volunteers (16 men, 24 women; mean age, 21.05 ± 2.17 years) reported to a clinical laboratory for 3 sessions, 1 week apart. At each session, participants were administered CNS Vital Signs. Outcomes included standard scores for the following CNS Vital Signs domains: verbal memory, visual memory, psychomotor speed, cognitive flexibility, complex attention, processing speed, reaction time, executive functioning, and reasoning.ResultsParticipants performed significantly better on the second session and/or third session than they did on the first testing session on 6 of 9 neurocognitive domains. Pearson r test-retest correlations between sessions ranged from 0.11 to 0.87. Intraclass correlation coefficients ranged from 0.10 to 0.86.ConclusionClinicians should consider using reliable change indices to account for practice effects, identify meaningful score changes due to pathology, and inform clinical decisions.Clinical relevanceThis study highlights the importance of clinicians understanding the psychometric properties of computerized neurocognitive tests when using them in the management of sport-related concussion. If CNS Vital Signs is administered twice within a small time frame (such as 1 week), athletes should be expected to improve between the first and second administration.

Project description:BackgroundLittle is currently known about the tapering practices of strongman athletes. We have developed an Internet-based comprehensive self-report questionnaire examining the training and tapering practices of strongman athletes.ObjectiveThe objective of this study was to document the test-retest reliability of questions associated with the Internet-based comprehensive self-report questionnaire on the tapering practices of strongman athletes. The information will provide insight on the reliability and usefulness of the online questionnaire for use with strongman athletes.MethodsInvitations to complete an Internet questionnaire were sent via Facebook Messenger to identified strongman athletes. The survey consisted of four main areas of inquiry, including demographics and background information, training practices, tapering, and tapering practices. Of the 454 athletes that completed the survey over the 8-week period, 130 athletes responded on Facebook Messenger indicating that they intended to complete, or had completed, the survey. These participants were asked if they could complete the online questionnaire a second time for a test-retest reliability analysis. Sixty-four athletes (mean age 33.3 years, standard deviation [SD] 7.7; mean height 178.2 cm, SD 11.0; mean body mass 103.7 kg, SD 24.8) accepted this invitation and completed the survey for the second time after a minimum 7-day period from the date of their first completion. Agreement between athlete responses was measured using intraclass correlation coefficients (ICCs) and kappa statistics. Confidence intervals (at 95%) were reported for all measures and significance was set at P<.05.ResultsTest-retest reliability for demographic and training practices items were significant (P<.001) and showed excellent (ICC range=.84 to .98) and fair to almost perfect agreement (? range=.37-.85). Moderate to excellent agreements (ICC range=.56-.84; P<.01) were observed for all tapering practice measures except for the number of days athletes started their usual taper before a strongman competition (ICC=.30). When the number of days were categorized with additional analyses, moderate reliability was observed (?=.43; P<.001). Fair to substantial agreement was observed for the majority of tapering practices measures (?range=.38-.73; P<.001) except for how training frequency (?=.26) and the percentage and type of resistance training performed, which changed in the taper (?=.20). Good to excellent agreement (ICC=.62-.93; P<.05) was observed for items relating to strongman events and traditional exercises performed during the taper. Only the time at which the Farmer's Walk was last performed before competition showed poor reliability (ICC=.27).ConclusionsWe have developed a low cost, self-reported, online retrospective questionnaire, which provided stable and reliable answers for most of the demographic, training, and tapering practice questions. The results of this study support the inferences drawn from the Tapering Practices of Strongman Athletes Study.

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The Test-Retest Reliability of the Photopic Negative Response (PhNR).

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