Table 3.

Characteristics of Studies Selected for Integrative Review, in Alphabetical Order by First Author

Study	Method	Sample Characteristics	Pertinent Findings	Component of Theory of Planned Behavior
Bair-Merritt et al. (2012)	Pilot study	N =55; M age: 7.4 y; 38% girls	29 families returned samples, typically within 2 weeks and before a reminder phone call was made. 5 provided info about why they had not returned the samples: 3 stated the child refused to provide saliva, 2 stated they kept forgetting.	Perceived behavioral control
Davis, Donzella, Krueger, and Gunnar (1999)	Quantitative	N =70; M age: 8 y; range: 7–12y; 47% girls	54 participants provided noon samples on at least 1 of 2 school days. Families sent collection materials to school with the child’s lunch, and children collected samples before eating. Data for evening and noon samples were analyzed separately over concerns that noon samples might be less reliable or reflect data from a group of more mature children.	Perceived behavioral control
Dietrich et al. (2013)	Quantitative	N =2230 children; M age: 11.1 y; range: 10.0–12.6 y; 50.8% girls	44 subjects excluded due to lack of compliance with the protocol (failing to take the first sample within 5 min of awakening or the second sample between 25 and 35 min after awakening). Non-compliant children had higher depression scores.	Perceived behavioral control
Dougherty et al. (2009)	Quantitative	N =166; M age: 43.42 mo.; range: 3–4 y; 43.6% girls	In families who did not participate in cortisol collection, parents were rated as higher on parental hostility, and children had experienced more stressful life events, compared to participating families.	Perceived behavioral control
Dougherty et al. (2013)	Quantitative	N =470; M age: 6.23 y; range: 5.28–7.58 y; 46.5% girls	255 families participated in salivary cortisol collection. Non-participating mothers had higher rates of lifetime depression compared to participating mothers.	Perceived behavioral control
Egliston et al. (2007)	Review	N/A	Authors raised questions as to how “non-invasive” cortisol sampling really is when used with infants. Authors reported that 7–8 month old infants strongly resist cortisol sampling methods, which may threaten internal validity. Authors suggested that resistance to sampling may lead to selective attrition, with the most reactive infants being lost to the study, but engaging parents in sample collection may improve compliance.	Perceived behavioral control
Fisher et al. (2007)	Quantitative	N =81; M age: 4.8 y; range: 2–6 y; 52% girls	36 mothers and children completed the diurnal cortisol protocol. Diurnal sampling protocol described as time-consuming and challenging for parents and children. Younger children and children of single mothers were less likely to successfully complete the protocol. Participating and non-participating families did not differ in terms of family socioeconomic status, age of mother, number of children per family, maternal smoking, observed level of maternal emotional support, mothers’ childhood withdrawal, or child IQ.	Perceived behavioral control
Granger et al. (2007)	Review	Included family life project (N =1193); range: 6–15 mo	In this study, white infants and those from middle to upper class families were less likely to be compliant than African-Americans or those from impoverished or low-income families.	Social norms
Groeneveld et al. (2010)	Quantitative	N =116; range: 20–40 mo.; 48% girls	Among other reasons, authors attributed low participation rate to childcare providers and parents disliking the idea of saliva samples being taken from the children.	Attitudes
Groschl et al. (2003)	Quantitative	N =252; range: 4 days–15 y; 50% girls	According to author experiences, salivettes are inappropriate for use with newborns due to danger of swallowing the swab, and refusal to keep the large swab inside their mouths. The authors report this procedure may cause stress to infants.	Perceived behavioral control
Gutteling et al. (2005)	Quantitative	N =29; M age: 5.31 y; 69% girls	18.96% of the cortisol samples on the school days and 41.37% on weekend days were missing. Missing values due to the parents/children not having the opportunity to collect it, or samples not containing enough saliva for analysis. 13 children did not participate in any weekend saliva collection due to logistical problems.	Perceived behavioral control
Hibel et al. (2014)	Quantitative	N =47; M age: 3.51 y; age range: 2–4 y	Differences in morning structure and routines on work and non-work days may affect sampling compliance. However, mothers did not self-report lower adherence on non-workdays, and analyses did not reveal a difference in children’s awakening cortisol on workdays compared to non-workdays.	Perceived behavioral control
Jessop and Turner-Cobb (2008)	Review	N/A	Challenges in saliva sampling varied by stage of childhood and adolescence, including differences in school routines, dietary habits, and sleep patterns. Adherence may be more reliable in parent-controlled environment of early childhood, and less reliable during puberty and early teenage years.	Perceived behavioral control
Kaitz et al. (2012)	Quantitative	N =174; M age: 45.26 mo.; 50.7% girls	12% of the sample missed at least one collection time point. Children who were resistant but did not outright refuse saliva collection had higher cortisol levels than compliant children. Children who resisted were perceived as having more internalizing symptoms than compliant children.	Perceived behavioral control
Laurent et al. (2014)	Quantitative	N =177; range: 3–6 y; 50% girls	5.8% of samples were missing because the parent failed to collect and/or return the sample, 1.0% missing because the sampling time was incorrect, and 21.4% were missing for other reasons (caseworker or family refusal, lost sample, child unable to do the collection).	Perceived behavioral control
Marsman et al. (2012)	Quantitative	N =1594; M age: 11.08 y; 50.3% girls	Children who participated in salivary cortisol collection did not differ from non-participating children in terms of gender, behavioral problems, perceived parental rejection, or perceived parental emotional warmth. Slight difference in SES between participating and non-participating children.	Perceived behavioral control
Marsman et al. (2008)	Quantitative	N =1768; M age: 11.09 y; 50.8% girls	Children who participated in collection did not differ from non-participating children in terms of gender or pubertal status. Children who did not participate were slightly older and had a higher mean body mass index than participating children.	Perceived behavioral control
Michels et al. (2012)	Quantitative	N =323; M age: 8.41 y; 51% girls	Cortisol levels differed between parents who reported sampling at the appropriate time and those who reported other times. Families who were non-compliant did not differ from others in terms of parental education, family structure, age or sex.	Perceived behavioral control
Michels et al. (2012)	Quantitative	N =444; M age: 8.4 y; range: 5–11 y; 50.7% girls	Most often missing were last two samples on second day of collection. Parents indicated that the specific timing and restrictions of sampling procedures were difficult, rather than sampling itself. Deviance from protocol often included food intake/tooth brushing prior to saliva collection, caffeine intake or physical activity, or use of influencing medications.	Perceived behavioral control
O’Farrelly and Hennessy (2013).	Qualitative	N =17; range: 2–5 y	Caregivers may have uncertainties and misconceptions regarding use for biological data, which may be heightened when asked to make decisions for their child. Theme of “lost for words:” Caregivers unable to articulate concerns due to unfamiliarity of biobehavioral research. Encouraging child participation in procedures and ensuring collection from a familiar adult would be helpful in younger children.	Attitudes social norms perceived behavioral control
Rotenberg and McGrath (2014)	Quantitative	N =201; M age: 12.67 y; range: 8–18 y; 45.3% girls	Both children and adolescents completed salivary cortisol collection upon awakening. Parents were highly involved with saliva collection in both age groups, with parents completing daily log for 97% of participants.	Perceived behavioral control
Saridjan et al. (2010)	Quantitative	N =366; range: 11.7–19.3 mo.; 43.4% girls	602/822 (68%) parents returned one or more saliva samples. Reported reasons for non-response: 1% too busy, 32% tried but failed to obtain saliva samples, 67% gave no reason. No difference in socioeconomic status, maternal smoking, or birth weight between participants and non-responders. Infants who successfully completed all saliva samples (n =366) were more likely to be boys.	Perceived behavioral control
Smith and Dougherty (2014)	Quantitative	N =95; M age: 49.93 mo.; range: 36–71 mo.; 53.1% girls	Parental compliance with saliva sampling procedures assessed based on parent self-report and an electronic monitoring device. Self reported compliance (83.0%) was significantly higher than objective compliance (68.8%) for the 2-day sampling period. From the first to second day of sampling, self reported compliance dropped from 84.5% to 79.5% and objective compliance dropped from 72.9% to 64.6%.	Perceived behavioral control
Sondeijker et al. (2008)	Quantitative	N =2935; M age: 11.09 y; 50.8% girls	2,230 (76%) of children participated in salivary cortisol collection. Participants and non-participants did not differ on sociodemographic variables, mental health, or teacher-rated problem behaviors. Children with highly disruptive behaviors and low socioeconomic status were less likely to successfully complete sampling.	Perceived behavioral control
Sondeijker et al. (2007)	Quantitative	N =2935; M age: 11.09 y; 50.8% girls	1,768 children provided saliva samples. No difference in gender, pubertal development, or behavioral problems between completers and non-completers. Children who did not provide samples were slightly older and scored higher on antisocial behavior than those who provided samples.	Perceived behavioral control
Stalder et al. (2013)	Quantitative	N =33; M age: 6.52 mo.; range: 2–12 mo	Number of missing study days was positively associated with infants’ current age, height and weight, suggesting that it was more difficult to obtain valid cortisol data from older and more physically developed infants.	Perceived behavioral control
Vermeer et al. (2010)	Quantitative	N =45; M age: 32 mo.; range: 18–40 mo	43% of saliva samples missing: parents or caregivers forgot to collect the saliva or the child refused to cooperate (22%), the samples did not contain enough saliva for analysis (20%), or samples were not within the detection limit for cortisol (0.8%). Children with complete cortisol data did not differ with respect to age, gender, or temperament.	Perceived behavioral control
Watamura et al. (2010)	Quantitative	N =79; M age: 4 y; range: 2–5 y; 46% girls	Discrepancy between reported and recorded collection times was positively correlated with cortisol levels on both weekend days and days when children attended childcare.	Perceived behavioral control
Watamura et al. (2003)	Quantitative	N =67; range: 2–38 mo.; 58% girls	Families of 36 children successfully collected samples at home. Children with and without saliva samples did not differ on ethnicity or maternal education.	Social norms perceived behavioral control
Watamura et al. (2004)	Quantitative	N =77; range: 12–36 mo	Difficulty with saliva collection reported in this young age range. In the first 51 families, nearly 60% of families were unable to provide any samples, and an additional 30% were missing some samples. After revising sampling procedures, 75% of families returned full saliva samples, and saliva sample volumes also increased.	Perceived behavioral control
Waynforth (2007).	Quantitative	N =75; M age: 5.1 y; range: 3–8 y	Most commonly reported reasons for noncompliance were that participation took too long, or the family was too busy to successfully complete the saliva collection regime and/or daily diary. Six parents were unable to collect saliva from their children using the equipment provided, and two parents did not follow instructions closely enough for their data to be useful. Non-compliance not correlated with parent’s full-time employment or socioeconomic status.	Perceived behavioral control

Note. M =mean. Y =years, Mo. =months.