Background

Reliance on verbal self-report of solar exposure in skin cancer prevention and epidemiologic studies may be problematic if self-report data are not valid due to systematic errors in recall, social desirability bias, or other reasons.

Methods

This study examines the validity of self-reports of exposure to ultraviolet radiation (UVR) compared to objectively measured exposure among children and adults in outdoor recreation settings in four regions of the United States. Objective UVR exposures of 515 participants were measured using polysulfone film badge UVR dosimeters on two days. The same subjects provided self-reported UVR exposure data on surveys and 4-day sun exposure diaries, for comparison to their objectively measured exposure.

Results

Dosimeter data showed that lifeguards had the greatest UVR exposure (24.5% of weekday ambient UVR), children the next highest exposures (10.3% ambient weekday UVR) and parents had the lowest (6.6% ambient weekday UVR). Similar patterns were observed in self-report data. Correlations between diary reports and dosimeter findings were fair to good and were highest for lifeguards (r = 0.38 – 0.57), followed by parents (r = 0.28 – 0.29) and children (r = 0.18 – 0.34). Correlations between survey and diary measures were moderate to good for lifeguards (r = 0.20 – 0.54) and children (r = 0.35 – 0.53).

Conclusions

This is the largest study of its kind to date, and supports the utility of self-report measures of solar UVR exposure.

Impact

Overall, self-reports of sun exposure produce valid measures of UVR exposure among parents, children, and lifeguards who work outdoors.

Background

Verbal self-report is the method most often used to assess sunscreen use, but the data may be confounded by recall error and social desirability. Sunscreen swabbing is a non-invasive procedure to objectively assess the presence of sunscreen on the skin. This study examined the agreement between verbal reports of sunscreen use from survey and diary measures and objectively measured sunscreen use.

Methods

Participants were 564 parents, children aged 5–10 years, and lifeguards at 16 swimming pools in four regions of the U.S. Participants completed self-reported measures, including baseline and final surveys, as well as a 4-day diary and objective swabbing measures of sunscreen presence on 2 separate days. Data were collected in 2006 and analyzed in 2006–2007.

Results

Levels of sunscreen use were relatively high based on surveys (65.7%); diary data (40.3%); and swabbing measures (59.1%). Agreement between swabbing and diary measures of sunscreen use was fair to good, with κ statistics for children at 0.40, followed by lifeguards at 0.34 and parents at 0.27. Validity coefficients across measures of sunscreen use were higher for lifeguards and parents than for children, and diary measures were higher than surveys. No systematic errors were found across groups or by gender, latitude, study arm, or risk category.

Conclusions

These findings are comparable to those in other validation studies, including studies of the validity of dietary assessments. Self-reported estimates of sunscreen use by diaries or surveys appear to be as good as objective measures.