Reliability and stability of mothers' reports about their pregnancies with twins.

The objective of this study was to determine if mothers' retrospective reports about events in their pregnancies with twins are reliable and stable. Six hundred and twenty-four mothers completed psychiatric interviews about their twins. These interviews also contained questions about the mothers' pregnancies, the perinatal period, and the child's early development. The mothers reported first on one twin and then on the other with interviews spaced from 3 days to 2 weeks apart. Thus mothers reported on the same pregnancy twice. Of these mothers, 47 were re-interviewed 6 to 18 months later by raters blind to the results of the initial interview. The twin design allowed us to compare the short-term reliability of the 624 mothers' reports of the same pregnancy. The re-interview of the 47 mothers enabled us to compare the stability of reports over a longer time period. Agreement between the reports was measured with the kappa statistic. Kappas were good to excellent for the short-term reports of pregnancy for each twin for the 624 mothers. Kappas were equally high for the 47 mothers that were re-interviewed 6 to 18 months later. Mothers show good reliability and stability of reporting about events during pregnancy.     

Accuracy of mothers' retrospective reports of smoking during pregnancy: comparison with twin sister informant ratings.

Retrospective assessment of maternal smoking or substance use during pregnancy is sometimes unavoidable. The unusually close relationship of twin sister pairs permits comparison of self-report data versus co-twin informant data on substance use during pregnancy. Information about smoking during pregnancy has been gathered from a series of mothers from an Australian volunteer twin panel (576 women reporting on 995 pregnancies), supplemented in many cases by independent ratings of their smoking by twin sister informants (821 pregnancies). Estimates of the proportion of women who had never smoked regularly (56-58%), who had smoked but did not smoke during a particular pregnancy (16-21%), or who smoked throughout the pregnancy (16-18%), were in good agreement whether based on self-report or twin sister informant data. However, informants underreported cases who smoked during the first trimester but then quit (1-3% versus 7-9% by self-report). Women who smoked throughout pregnancy (by informant report) rarely denied a history of regular smoking (< 1%), although a small proportion of apparent false negative cases were identified where they either denied smoking during a pregnancy (9%) or denied smoking beyond the first trimester (10%). We conclude that retrospective smoking data can safely be used to identify potential associations of later child outcomes with maternal smoking during pregnancy.     

Test-retest reliability and construct validity of the ENERGY-parent questionnaire on parenting practices, energy balance-related behaviours and their potential behavioural determinants: the ENERGY-project

ABSTRACT: BACKGROUND: Insight in parental energy balance-related behaviours, their determinants and parenting practices are important to inform childhood obesity prevention. Therefore, reliable and valid tools to measure these variables in large-scale population research are needed. The objective of the current study was to examine the test-retest reliability and construct validity of the parent questionnaire used in the ENERGY-project, assessing parental energy balance-related behaviours, their determinants, and parenting practices among parents of 10-12 year old children. FINDINGS: We collected data among parents (n = 316 in the test-retest reliability study; n = 109 in the construct validity study) of 10-12 year-old children in six European countries, i.e. Belgium, Greece, Hungary, the Netherlands, Norway, and Spain. Test-retest reliability was assessed using the intra-class correlation coefficient (ICC) and percentage agreement comparing scores from two measurements, administered one week apart. To assess construct validity, the agreement between questionnaire responses and a subsequent interview was assessed using ICC and percentage agreement. All but one item showed good to excellent test-retest reliability as indicated by ICCs > .60 or percentage agreement [greater than or equal to] 75%. Construct validity appeared to be good to excellent for 92 out of 121 items, as indicated by ICCs > .60 or percentage agreement [greater than or equal to] 75%. From the other 29 items, construct validity was moderate for 24 and poor for 5 items. CONCLUSIONS: The reliability and construct validity of the items of the ENERGY-parent questionnaire on multiple energy balance-related behaviours, their potential determinants, and parenting practices appears to be good. Based on the results of the validity study, we strongly recommend adapting parts of the ENERGY-parent questionnaire if used in future research.     

Thymus-derived peripheral lymphocytes from human newborns inhibit division of their mothers' lymphocytes.

Lymphocytes from human newborns inhibit division of their mothers' lymphocytes. Three days after we cultured equal numbers of cells from a mother and her baby in the presence of PHA, mitosis of the mother's lymphocytes was suppressed 13-fold compared to that of the baby's lymphocytes. At the end of 3 days the number of baby's lymphocytes were doubled those of the mother's. The survival rates and mean mitotic indexes of both pairs of cell were roughly equivalent (mean +/- S.E: baby 2.4 +/- 0.8; mother 2.6 +/- 0.7), indicating that the lack of dividing lymphocytes from the mother was caused by inhibited division of the mother's lymphocytes, no enhanced growth of the newborn's cells. The cell population in newborns that is responsible for the inhibition effect resides in the T cell-enriched population. Lymphocytes from one newborn were not able to inhibit division of lymphocytes from another newborn, suggesting that lymphocytes from newborns could continue to divide despite their inhibitory effect. Other experiments showed that actively dividing fetal fibroblasts, amnion cells from the newborn, and continuous T lymphoblastoid cell lines were unable to inhibit mitosis of lymphocytes of the mother.     

The reliability and validity of short-distance sprint performance assessed on a nonmotorized treadmill

This study examined the interday and intraday reliabilities and validities of various sprint performance variables on a nonmotorized treadmill (NMT) over distances of 10, 20, and 30 m. After habituation, 12 male team-sport players performed 3 sprints on the NMT on 2 separate days and an assessment of overground running performance, separated by 24 hours. Measurements included sprint times, mean and peak sprint speeds, and step length and frequency. Data analysis revealed no significant mean differences (p > 0.05) between NMT variables recorded on the same day or between days. Ratio limits of agreement indicated that the best levels of agreement were in 20-m (1.02 ×/÷ 1.09) and 30-m (1.02 ×/÷ 1.07) sprint times, peak (1.00 ×/÷ 1.06) and mean (0.99 ×/÷ 1.07) running speed, and step length (0.99 ×/÷ 1.09) and frequency (1.01 ×/÷ 1.06). The poorest agreement was observed for time to peak running speed (1.10 ×/÷ 1.47). These reliability statements were reinforced by coefficients of variation being <5% for all the variables except time to peak running speed (11%). Significant differences (p < 0.05) were observed between NMT and overground sprint times across all distances, with times being lower (faster) by approximately 25-30% overground. The correlations between NMT and overground variables were generally modest (0.44-0.67), and optimal for time to cover 30 m on day 2. Our data support NMT ergometry as a reliable tool for most of the sprint performance variables measured and reveal that the fastest 30-m overground sprinters were likely to be identifiable via NMT ergometry.     

The validity and reliability of the 1RM bench press using chain-loaded resistance

The purposes of this study were to determine the validity and test-retest reliability of the 1 repetition maximum (1RM) chain-loaded, free-weight bench press (CBP) and to examine possible learning effects that may occur between the test-retest measurements. Nine resistance-trained men (20.58 +/- 1.31 years, 188.24 +/- 9.29 cm, 92.07 +/- 16.94 kg) and seven resistance-trained women (20.42 +/- 0.98 years, 175.61 +/- 9.32 cm, 73.61 +/- 10.80 kg) participating in Division II college basketball completed this study. Two familiarization sessions took place using light to moderate loads to learn proper technique. The subjects completed a 1RM test on the traditional plate-loaded bench press 4 days before completion of the CBP 1RM, which was followed by 4 days of rest before completing the retest. Intraclass correlation coefficients (ICC) and the percent coefficients of variation (CV) were used to determine relative and absolute test-retest reliability. Concurrent validity was determined from the Pearson correlation coefficients between the CBP and the plate-loaded bench press. Test-retest differences were analyzed with the paired t-test. ICC and CV for the men (r = 0.99, 1.4%) and women (r = 0.93, 3.5%), respectively indicate that highly reproducible 1RM scores can be found with the CBP. High validity was also found with high correlations between the CBP and plate-loaded bench press for the men (r = 0.95) and women (r = 0.80). A statistically significant (p = 0.04) but clinically small (2.57 kg) shift in the mean occurred between the CBP test and retest for the men, whereas no change occurred for the women. The data indicate that valid and reliable 1RM scores can be found after two familiarization sessions in men and women athletes who have previous resistance training experience.     

The validity and reliability of the Socioeconomic Status Instrument for assessing prostate cancer patients

Background: Because of the lack of consistency in the associations of the socioeconomic status (SES) of prostate cancer (PC) patients from diverse racial and ethnic backgrounds with PC health outcomes, I created the Socioeconomic Status Instrument (SESI) from the Demographic and Health Access components of the Behavioral Risk Factor Surveillance System 2004 Questionnaires and the socioeconomic indices of the subjects’ residential counties to better assess the SES of PC patients. Methods: The SESI was tested on 220 consecutive subjects with pathologically confirmed PC at the Veterans Affairs Medical Center in Houston, TX. A team that included an epidemiologist, a validation statistician/health services research scientist, and PC survivors assessed the content validity of the SESI. The construct validity of the SESI was assessed with factor analysis by extracting and analyzing 5 principal components based on the subjects’ individual responses on the assessment: county socioeconomic characteristics, individual socioeconomic characteristics, financial distress, increased domestic burden with limited earnings, and affluence. The internal consistency reliability of the SESI was assessed with Cronbach's alpha coefficients. Results: Based on the reviews of the SESI, all of the initial 10 items were retained. The correlations between individual responses on the SESI were similar to the results of previous studies. The 5 principal components that I assessed accounted for 71.5% of the variance. Factor loadings ranged from 0.66 to 0.98 and communalities ranged from 0.55 to 0.94. County socioeconomic characteristics accounted for 22.6% of the variance, whereas individual socioeconomic characteristics accounted for 14.6% of the variance. The overall Cronbach's alpha coefficient was 0.78. Conclusions: The SESI is valid and reliable. Accurate measurements of the SES of PC patients would provide better guidance for future research and care deliveries.     

Note on the validity of constant field assumption in relation to the exact solution of Nernst--Planck equations

By means of the exact solution of the Nernst-Planck equations, it can be demonstrated that the constant electric field assumption is incompatible with the stationary flows of ions in the homogeneously charged membrane. The exact solution of the Nernst-Planck equation system is readily given by the power series expansion method. The constant field assumption is valid for membrane in which the fixed charge can move freely and neutralize the charge of permeating ions.The parabolical electric potential is shown to be incompatible with the homogeneously charged membranes including the neutral membranes.     

The reliability and validity of fatigue measures during short-duration maximal-intensity intermittent cycling

The purpose of the present study was to assess the reliability and validity of fatigue measures, as derived from 4 separate formulae, during tests of repeat sprint ability. On separate days over a 3-week period, 2 groups of 7 recreationally active men completed 6 trials of 1 of 2 maximal (20 x 5 seconds) intermittent cycling tests with contrasting recovery periods (10 or 30 seconds). All trials were conducted on a friction-braked cycle ergometer, and fatigue scores were derived from measures of mean power output for each sprint. Apart from formula 1, which calculated fatigue from the percentage difference in mean power output between the first and last sprint, all remaining formulae produced fatigue scores that showed a reasonably good level of test-retest reliability in both intermittent test protocols (intraclass correlation range: 0.78-0.86; 95% likely range of true values: 0.54-0.97). Although between-protocol differences in the magnitude of the fatigue scores suggested good construct validity, within-protocol differences highlighted limitations with each formula. Overall, the results support the use of the percentage decrement score as the most valid and reliable measure of fatigue during brief maximal intermittent work.     

Interrater reliability and time measurement validity of speed-agility field tests in adolescents

The aim of this study was to examine the interrater reliability (trained vs. untrained raters) and criterion-related validity (manual vs. automatic timing) of the 4 × 10-m shuttle run and 30-m running speed tests (times measured). The study comprised 85 adolescents (38 girls) aged 13.0-16.9 years from the Healthy Lifestyle in Europe by Nutrition in Adolescence study. The time required to complete the 4 × 10-m shuttle run and 30-m running tests was simultaneously measured (a) manually with a stopwatch by both trained and untrained raters (for interrater reliability analysis), and (b) by using photoelectric cells (for validity analysis). Systematic error, random error, and heteroscedasticity were studied with repeated-measured analysis of variance and Bland-Altman plots. The systematic error for untrained vs. trained raters and the untrained raters vs. photoelectric cells were in all cases ～0.1 seconds (p < 0.01), that is, untrained raters recorded higher times. No systematic error was found between trained raters and photoelectric cells (p > 0.05). No heteroscedasticity was shown in any case (p > 0.05). The findings indicate that manual measurements by a trained rater, using a stopwatch, seem to be a valid method to assess speed and agility fitness testing in adolescents. Researchers must be trained to minimize the measurement error.     

Discriminant validity, responsiveness and reliability of the rheumatoid arthritis-specific Work Productivity Survey (WPS-RA)

Introduction  

The rheumatoid arthritis-specific Work Productivity Survey (WPS-RA) measures the impact of rheumatoid arthritis (RA) and treatment on patient productivity within and outside the home. It contains nine questions addressing employment status, productivity within and outside the home, and daily activities. The objective of this paper was to evaluate the discriminant validity, responsiveness, and reliability of the WPS-RA in patients with active RA.     

Assessing the validity of sexual behaviour reports in a whole population survey in rural Malawi

Background

Sexual behaviour surveys are widely used, but under-reporting of particular risk behaviours is common, especially by women. Surveys in whole populations provide an unusual opportunity to understand the extent and nature of such under-reporting.

Methods

All consenting individuals aged between 15 and 59 within a demographic surveillance site in northern Malawi were interviewed about their sexual behaviour. Validity of responses was assessed by analysis of probing questions; by comparison of results with in-depth interviews and with Herpes simplex type-2 (HSV-2) seropositivity; by comparing reports to same sex and opposite sex interviewers; and by quantifying the partnerships within the local community reported by men and by women, adjusted for response rates.

Results

6,796 women and 5,253 men (83% and 72% of those eligible) consented and took part in sexual behaviour interviews. Probing questions and HSV-2 antibody tests in those who denied sexual activity identified under-reporting for both men and women. Reports varied little by sex or age of the interviewer. The number of marital partnerships reported was comparable for men and women, but men reported about 4 times as many non-marital partnerships. The discrepancy in reporting of non-marital partnerships was most marked for married women (men reported about 7 times as many non-marital partnerships with married women as were reported by married women themselves), but was only apparent in younger married women.

Conclusions

We have shown that the under-reporting of non-marital partnerships by women was strongly age-dependent. The extent of under-reporting of sexual activity by young men was surprisingly high. The results emphasise the importance of triangulation, including biomarkers, and the advantages of considering a whole population.