The validity of self-reported condom use among adolescents.

BACKGROUND: Research and public health interventions designed to reduce the risk of sexually transmitted diseases (STDs) often are based on self-reported condom use. Yet, validation of self-reported condom use, in particular with adolescents, has rarely been described in the literature. METHODS: Baseline data were obtained from 540 adolescents, 13-21 years of age, enrolled in a 1-year longitudinal study of health beliefs, sexual behaviors, and STD acquisition. Of the 445 participants reporting to be sexually active, 404 (90.8%) agreed to a complete physical examination, including a genital examination, with STD screening after completing the self-administered written questionnaire. Participants' written self-report of condom use was compared to histories obtained by clinicians and laboratory diagnosis of acute STDs to assess validity of written self-report. RESULTS: Complete data were available for 321 females and 77 males of whom 52 females and 5 males had laboratory evidence of 63 infections. Although three individuals who had STDs reported to be consistent users of condoms, a significant association (P < 0.05) was found between those who reported more frequent condom use with the last two partners and the absence of STDs. CONCLUSION: In this group of adolescents, self-report of condom use with the last two partners was associated with the absence of an acute STD. This finding suggests that self-reported condom use is a valid indicator of risk for STDs, with implication for those working with adolescents clinically and in research contexts.

PIP: Although most research on sexually transmitted disease (STD) risk behavior surveillance and prevention is based on self-reports of condom use, there have been few attempts to assess the extent to which self-reports accurately reflect true behavior. To validate this methodology, baseline data were obtained from 540 US male and female adolescents 13-21 years of age enrolled in a 1-year longitudinal study of sexual behaviors and STDs. Of the 445 participants who reported they were sexually active, 398 underwent genital examination and STD screening. 52 females and 5 males had laboratory evidence of acute STDs. 15.2% of females and 32.3% of males reported consistent condom use with their most recent sexual partner. Although 3 young people with STDs had reported they were consistent condom users, a significant (p 0.05) inverse association was found between consistency of reported condom use with the last 2 sexual partners and the occurrence of an acute STD. This finding suggests that, even among adolescents, self-reported condom use is a valid indicator of STD risk.

Seasonal branch and fine root growth of juvenile loblolly pine five growing seasons after fertilization.

In 1989, we established two replications of two fertilization treatments in a 10-year-old loblolly pine (Pinus taeda L.) plantation. Between March and September 1993, branch internode and needle fascicle expansion in the upper and lower third of crowns were measured weekly on three south-facing branches of each of four trees, and new root initiation and elongation were measured at 10-day intervals in three vertical rhizotrons per plot. In one replication, soil water content was measured daily. Fertilization significantly increased the expansion of first flush internodes in the upper crown and first flush needle fascicles in the upper and lower crown. New root growth was stimulated by fertilization in the second half of the growing season. The timing of root growth responses to fertilization corresponded to branch phenologies in the upper and lower crown that were conducive to increased basipetal transport of photosynthate. We conclude, therefore, that new root growth was linked to source-sink activities in the crown. Root initiation was greater in the upper than in the lower part of the soil profile; however, as the growing season progressed and water deficit increased, this relationship was reversed. The effect of soil depth on seasonal root growth was closely associated with water availability, suggesting that root initiation deep in the soil profile is critical for the continued production of new roots in environments subjected to short-term, but relatively severe, water deficits.

Use of compartmental analysis to describe effects of dietary fat saturation and load on plasma triglyceride dynamics in the rat.

Model-based compartmental analysis was used to interpret data on temporal changes in plasma triglyceride (TG) response to a chronic infusion of chylomicrons (CM) in the rat. Male rats were fed purified diets which varied in fat load [L = 10% (w/w), H = 30%] and P/S ratio (P = 4.6, S = 0.2). Lymph CM isolated from donor rats which were absorbing the P or S fat were infused into recipients for 8 h on 3 consecutive days: on d 1 and 3, CM infusion rate reflected the fat content of the previous diet and on d 2, the other load; the infusion replaced dietary fat. Serial plasma samples from each period were analyzed for TG concentration; TG distribution in plasma lipoproteins and liver lipids was measured after d 3. To describe observed group average data, a compartmental model was developed using the Simulation, Analysis and Modeling computer program. Two compartments were needed in plasma (CM vs nonCM TG); each had 2 outputs: removal of TG-fatty acids by lipoprotein lipase (LPL) and uptake of remnant lipoproteins by the liver. After a delay in the liver, there were 3 fates for TG-derived fatty acids: oxidation, retention, or secretion in very low density lipoproteins. Simulation of changes in the rate constant for total CM TG turnover indicated that the basal level of LPL rose rapidly and dramatically in response to TG infusion; the rise was higher for H vs L. After 3-5 h, apparent LPL activity decreased. Simulation of the rate of CM TG turnover indicated that the turnover rate rose immediately after infusion began to levels higher than the infusion rate, and then came into a slight negative balance. Although the observed data could be qualitatively described based on current understanding of TG metabolism, application of model-based compartmental analysis generated testable hypotheses about quantitative aspects of the system dynamics.

Many diagnostic tests may be unnecessary.

Hospital installs system for concurrent review of diagnostic test ordering in which judgment criteria are set in consensus fashion by physicians.