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Correlates of mobile screen media use among children aged 0–8: a systematic review
  1. Susan Paudel1,
  2. Jonine Jancey2,
  3. Narayan Subedi3,
  4. Justine Leavy2
  1. 1 School of Public Health, Curtin University, Perth, Western Australia, Australia
  2. 2 Collaboration for Evidence, Research and Impact in Public Health (CERIPH), School of Public Health, Curtin University, Perth, Western Australia, Australia
  3. 3 Department of Community Medicine and Public Health, Maharajgunj Medical Campus, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
  1. Correspondence to Susan Paudel; replysusan{at}gmail.com

Abstract

Objective This study is a systematic review of the peer-reviewed literature to identify the correlates of mobile screen media use among children aged 8 years and less.

Setting Home or community-based studies were included in this review while child care or school-based studies were excluded.

Participants Children aged 8 years or less were the study population. Studies that included larger age groups without subgroup analysis specific to the 0–8 years category were excluded. Eight electronic databases were searched for peer-reviewed English language primary research articles published or in press between January 2009 and March 2017 that have studied correlates of mobile screen media use in this age group.

Outcome measure Mobile screen media use was the primary outcome measure. Mobile screen media use refers to children’s use of mobile screens, such as mobile phones, electronic tablets, handheld computers or personal digital assistants.

Results Thirteen studies meeting the inclusion criteria were identified of which a total of 36 correlates were examined. Older children, children better skilled in using mobile screen media devices, those having greater access to such devices at home and whose parents had high mobile screen media use were more likely to have higher use of mobile screen media devices. No association existed with parent’s age, sex and education.

Conclusion Limited research has been undertaken into young children’s mobile screen media use and most of the variables have been studied too infrequently for robust conclusions to be reached. Future studies with objective assessment of mobile screen media use and frequent examination of the potential correlates across multiple studies and settings are recommended.

Trial registration number This review is registered with PROSPERO International Prospective Register of Ongoing Systematic Reviews (registration number: CRD42015028028).

  • children
  • mobile media use
  • screen time
  • correlates
  • systematic review

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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Strengths and limitations of this study

  • This review summarises current peer-reviewed literature on correlates of mobile screen media use among children aged 8 years and less. and is guided by a published protocol paper.

  • The review incorporated a robust research strategy and inclusion exclusion criteria, which identified up-to-date keywords with the assistance of public health librarian; and searched eight relevant databases.

  • All the reviewed studies were cross-sectional in design making it difficult to derive a casual inference.

  • Study sample sizes ranged from 149 to 3206, which may have impacted on the findings.

  • Association and consistency could not be determined in this review due to the study findings being segregated across different mobile screen media types, making the findings largely descriptive.

Background

Young children are increasingly exposed to multiple screens including both the traditional fixed screens, such as televisions and desktop computers and newer mobile screen media devices such as smartphones and electronic tablets.1 Specifically, there has been a rapid uptake of mobile screen media devices in recent years, among young children.2 3 This is largely facilitated by the characteristics of handheld devices, their portability, screen size, decreasing cost, multiple applications and interactive ability.4 5 Because of the increasing uptake and use of mobile screen media devices, the daily screen time of traditional media such as television has decreased6 while the time spent on the former has increased, especially in many developed countries.4 Though television is still the dominant media for family time, solitary viewing by children is mostly achieved using mobile screen media devices.7 This increasing exposure and accessibility to mobile screen media devices creates a conundrum. On one hand, mobile screen devices may increase children’s sedentary behaviour, but they also have the potential to increase play opportunities, creating a tension for public health, and parents alike.8 Furthermore, the pleasure a child derives from interacting with these touch screens may lead to increased and habitual use.9 Nevertheless, there are also some benefits associated with interactive mobile screen media devices use, such as learning opportunities and face-to-face connection with distant family and friends and play opportunities.10 11 Similarly, engagement with active video games has been reported to promote light to moderate physical activity.12

Health guidelines recommend that children aged less than 2 should be exposed to a limited amount of educational mobile screen media use, while for those aged 2–5, the daily screen time should be less than 1 hour.10 13–15 However, worldwide, a significant proportion of young children are exceeding the recommended exposure time.5 For example, in an urban community in Philadelphia, USA, nearly half of 1-year-old children were reportedly using mobile screen media devices on a daily basis, with use increasing with age.4 Surprisingly, 75% of children had their own mobile device by the age of 4.4 It seems parents are increasingly allowing their young children to use mobile screen media devices, especially smartphones and electronic tablets, to keep them occupied when they are doing household chores or shopping, to calm children in public places and to put children to sleep.3 4 16

Despite the increase in the use of mobile screen media devices such as smartphones, electronic tablets, handheld computers and personal digital assistants (PDA) by young children, very limited research has been carried out to identify the correlates associated with their increased use.4 Currently, screen time research is dominated by fixed screens with scant attention paid to mobile screen media devices.10 Systematic reviews to identify the correlates of mobile screen media use among young children are almost non-existent with previous reviews focusing on sedentary behaviours or television viewing.17–19

Considering the increasing availability, ownership and use of mobile screen media devices (smartphones, electronic tablets, handheld computers, PDAs) among young children, identification of the correlates of mobile screen media use specific to children 8 years and less is crucial. The purpose of this review was to systematically search and critically review the published peer-reviewed literature to identify the correlates of mobile screen media use among children 8 years and less. Correlates are classified into proximal and distal factors using a bioecological model to facilitate comparison with the existing literature.17 20 The model provides a strong theoretical basis to understand human behaviour21 and has been described in detail elsewhere.22

Methods

This systematic review is based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) statement23–25 and is registered with PROSPERO International Prospective Register of Ongoing Systematic Reviews (registration number: CRD42015028028). The study used already published, deidentified data and hence is exempt from the ethics approval process. A detailed description of the methods is available in the protocol article.22 As discussed in the protocol article, initially the database search was planned for articles published between 2009 and 2015.22 However, considering the increasing number of articles studying mobile screen media recently, the search was extended to March 2017.

Outcome measure

Mobile screen media use was the primary outcome measure. Mobile screen media use refers to children’s use of mobile screens, such as mobile phones, electronic tablets, handheld computers or PDAs. The term ‘screen time’ is used to denote both the fixed screens and mobile media screen device use. This terminology is used when referring to the screen time guidelines for children and to refer to other articles that have studied children’s total screen time including both fixed and mobile screens.

Correlates of mobile screen media use have been placed into five categories as per the bioecological model.17 18 The five categories are:

  • Child biological and demographic factors include age, sex and body mass index (BMI).

  • Family biological and demographic factors include demographic and biological characteristics of the family members (particularly parents) and their education, occupation and income.

  • Family structure factors include the number of siblings, family size and family type.

  • Behavioural factors include the child’s behavioural characteristics and their skills and attitudes.

  • Sociocultural/environmental factors include social, physical and environmental factors within the home setting and community, and parental behavioural factors such as their screen media skills, beliefs and attitudes towards the mobile screen media and self-efficacy to limit their children’s screen viewing behaviours.

Direction of association has been reviewed separately for: (A) smartphones, (B) electronic tablets, (C) touch screens, and (D) any media device (defined as the combination of traditional media plus at least one other mobile screen media device).

Eligibility criteria

The studies eligible for inclusion were peer-reviewed primary research articles with information on mobile screen media use, parent-child co-use or adherence to screen time guidelines as the outcome measure, which investigated the correlates of mobile screen media use among children aged 8 and less; based in home or community setting; and published, or in press in English language journals between January 2009 and March 2017. The full description of the alignment of the research question to the PECO (Population, Exposure, Comparison and Outcome) format along with the exclusion criteria is presented in table 1.

Table 1

Research question using PECO format

Search strategy and study selection

Eight electronic databases (Medline, Scopus, Embase, CINAHL Plus, Pubmed, ProQuest, PsycINFO and Web of Science) were searched for articles published between January 2009 and March 2017. Child-related keywords including child*, preschool, infant, kid and toddler and screen-related keywords including screen time, screen viewing, mobile phone, cell phone, smartphone*, PDA, tablet*, iPad*, handheld media, handheld computer* were used to locate potential papers in the databases. The search was carried out during September to October 2015 and replicated in March 2017. The search commenced with Medline and the identified papers were excluded when searching other databases. However, only Embase, ProQuest and CINAHL Plus provided that option. Duplicate records were manually removed after compiling all the searches. The search strategy used in Medline database is presented in table 2. A total of 1909 articles were identified through searching the eight databases. To ensure that all relevant articles were identified, a manual search of the reference lists of the systematic reviews was also carried out along with the checking of the Google Scholar profile of authors with frequent publication in this field. A total of seven papers were retrieved from the manual searching process.

Table 2

Search strategy used in Medline database

Endnote (V.X7.5) software was used for managing all the identified articles (n=1916). Duplicate articles (n=376) were removed. The remaining articles (n=1540) were then screened by title by two authors (SP and NS). From this, irrelevant titles (n=1029) were excluded. The abstracts of the remaining articles (n=511) were also reviewed by SP and NS; and a further 427 articles were excluded. Full texts of the remaining articles (n=84) were retrieved and reviewed by all the four researchers (SP, NS, JJ and JL) against the inclusion/exclusion criteria, resulting in 13 papers being included in this systematic review. The authors of this systematic review were not blinded to the name, journal title or institutional affiliation of the authors of the articles selected. The process of study selection has been presented using the PRISMA flow diagram in figure 1.

Figure 1

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow chart for study selection.

Assessment of included papers

A modified version of the checklist by Downs and Black26 was used to assess the quality of studies and the risk of bias. Out of 27 suggested checklist items, relevant items in the themes of reporting (questions 1–3, 6, 7, 10), external validity (questions 11, 12) and internal validity bias (questions 18, 20) were considered appropriate for this review. A score of ‘1’ was allocated for ‘Yes’ and a score of ‘0’ was allocated for ‘No’ and ‘Unable to determine’. Out of a possible score of 10, a total score greater than 5 indicated a quality paper. Three researchers (SP, JJ and JL) independently carried out the appraisal using the checklist and the final quality score was ascertained by comparing each of their scores. Discrepancies in scores were reassessed jointly, and a consensus reached.

Data extraction and management

In order to maintain consistency and avoid bias, a data extraction table was developed. Information on study design, country of study, age group of participants, sample size, main outcome variables, correlates and measures of association was extracted by one author (SP). Mean duration of screen viewing specific to individual devices was also extracted when available. Adjusted OR and standardised coefficients were extracted in order to establish the correlates. Since there were few studies that assessed a particular variable, association and consistency could not be determined.

Results

Study characteristics

Thirteen studies published between 2013 and 2017 were included in the review. Six were published in 2015,1 27–31 four in 201632–35 and one in 2014,36 201337 and 2017.38 The majority of the eligible studies were conducted in high-income countries with four from the USA,1 27 31 33 three from the UK,28 29 37 two from Canada34 38 and one from the Netherlands,30 Hong Kong,36 Malaysia32 and Czech Republic.35 All 13 studies were cross-sectional in design. The studies’ quality scores ranged from 6 to 10 with a mean score of 7.85, indicating all were considered quality studies.

The study sample sizes ranged from n=149 to n=3206. Two studies reported using weighted data to be representative of the national population,1 31 two studies used random sampling,34 35 one used stratified random sampling,32 while all other studies used non-representative techniques.27–30 33 36–38 The mean age of participants was clearly stated in eight studies28 30–35 38 while four provided frequencies in different age groups.27 29 36 37 However, Connell et al 1 did not report children’s mean age. Based on the available data, the mean age of the children was (4.74±1.72) years. The descriptive characteristics of the included studies are presented in table 3.

Table 3

Description of included studies

Mobile screen media use

Eleven studies reported screen viewing as the outcome measure,28–38 one reported adherence to the American Academy of Paediatrics (AAP) screen time guidelines27 and one reported parent-child co-use of media.1

Children’s mobile screen media use in all 13 studies was measured by parental self-report. One paper reported face validity, content validity and test-retest reliability of the instrument used,36 and five of the research questionnaires had been used in previous studies.1 27 31 32 38 Three studies stated parental-proxy reports as having reasonable reliability and validity to measure children’s mobile screen media use.28 29 37 The other studies did not report on the reliability and validity of their instrument.30 33–35 Overall, the mean duration of mobile screen media use could not be determined as only five studies reported the average duration,27 30–32 35 while all other studies categorised participants into groups, such as less than 2 hours and more than 2 hours of screen media use.1 28 29 33 34 36–38

Device use and correlates

In total, 36 correlates of mobile screen media use were studied. Of these correlates, children’s age was reported eight times, parental media use (fixed and mobile screens) seven times, family income five times and three variables (child sex, parental age and education) four times. The remaining correlates were studied even fewer times (see tables 4 and 5). Association and consistency of the variables could not be determined as a majority of the variables were studied in less than three studies.

Table 4

Demographic and biological correlates of mobile screen media use and direction of association

Table 5

Environmental and behavioural correlates of mobile screen media use and direction of association

Four studies reported an association specific to smartphones1 29 31 37 and electronic tablets.1 28 31 33 Nikken and Schols30 reported combined results for touch screens (smartphones and electronic tablets) while the other six studies reported correlates for electronic media, which included both traditional (eg, televisions, computers) and new devices (eg, mobile phones and electronic tablets).27 32 34–36 38 Use of a PDA was not studied.

Correlates of mobile media use

Child biological and demographic factors

Six of the eight studies (75%) reported a positive association between the child’s age and mobile screen media use27 31 33 34 36 38 (table 4). Older children were more likely to use smartphones, tablets or any media compared with younger children.27 31 33 34 36 38 Carson and Kuzik concluded that for every 1-month increase in age, the use of any media increased by 9.3 min/day (95% CI 2.8 to 15.8).38 However, Connell et al examined parent-child co-use of smartphones and electronic tablets and reported an inverse association, indicating older children were less likely to co-use with parents.1 In contrast, Nikken and Schols30 concluded that the child’s age had no significant association with the use of touch screens. Women were more likely to use any media for a longer duration than their male counterparts32 38 but there was no association with sex specifically in regard to touch screen use.1 30 No association was found between the use of any media and child BMI.27

Family biological and demographic factors

Four studies reported an association between parental age and their children’s mobile screen media use1 27 33 36 (see table 4). Of these, three reported no statistically significant association,1 27 while Wu et al found a negative association, indicating that screen devices (both fixed and mobile screens) were more frequently used by children with younger parents.36

Mixed associations were found between family income and children’s mobile screen media use (see table 4). Two studies30 38 reported a positive association, indicating that children from high-income families were using touch screens or any media device longer than those from low-income families. Conversely, studies by Pempek and McDaniel33 and Lee et al 32 found no association with family income, and Wu et al 36 reported a negative association. Wu et al also found a negative association between parent’s occupational status and children’s mobile screen media use.36 Furthermore, children of stay-at-home parents used screen devices more frequently than those whose parents were employed.36

No association was identified between young children’s smartphone, electronic tablet or any touch screen use and parent’s sex.1 30 Similarly, parent’s educational status,1 30 32 33 country of birth38 and language27 did not show any significant association with children’s mobile screen media use.

Family structure factors

Two studies reported family factors associated with children’s mobile screen media use30 36 (table 4). A positive association was reported between the number of children and use of televisions, computers, tablets and mobile phones,36 and when there were two or more children, they were more likely to use screen devices (both fixed and mobile screens) for talking with friends compared with those families with one child.36

Behavioural factors

Ability or skill of children to use mobile screen media devices was the only behavioural skill studied and was found to have a positive association with frequency and duration of device use30 (see table 5). Furthermore, children who were better skilled in using mobile screen media devices had greater access to these devices in their bedrooms and spent more time on them than less skilled children.30

Sociocultural/environmental factors

In total, 21 sociocultural/environmental correlates were investigated (see table 5). Parental screen time/media use (both mobile and fixed screens) was the most studied variable.1 27 30 31 33 35 37 Two studies concluded that there was no statistically significant association between parental smartphone use and their children’s use.1 37 Positive associations have also been reported for parental screen time and children’s use of tablets, touch screen devices or any media.1 27 30 31 33 35 Sigmund et al concluded that the association between parental and children any media use was stronger during weekends than on weekdays.35

Parental attitudes about the effects of mobile screen media on children were positively associated with smartphone and electronic tablet use for older young children (4–8 years).31 More positive parental attitudes towards these devices resulted in greater use by the children.31 Similarly, parental belief in the negative effects of mobile screen media devices was not associated with children’s use of these devices.30 However, children were more likely to use mobile screen media devices when parents believed that these devices were helpful as a behavioural regulation tool,30 while parental nurturing and self-efficacy to limit mobile media use were negatively associated with electronic tablet use.28

Children in parental care were more likely to have higher any media use than children in child care.38 Similarly, any media use was higher during weekends than weekdays.35 The number of media devices at home and in the child’s bedroom was positively associated with increased smartphone use.37 Jago et al 37 concluded that the greater the number of devices, the greater the use, while Asplund et al 27 reported no such association.

Discussion

This systematic review identified 36 reported correlates of mobile screen media use among children aged 8 years or less from 13 studies. Although this review searched for eligible articles published between 2009 and 2017, the included studies were published between 2013 and 2017, indicating limited but recent and increasing interest in mobile screen media use-related research.

This review found that children aged between 4 and 8 years were more likely to have higher mobile screen media use. Similarly, those who were better skilled in using the devices had more access to media devices at home, and higher parental use of mobile screen media was more likely to have higher mobile screen media use. The bioecological model posits that human behaviour is affected by intrapersonal factors, interpersonal factors and distal factors which interact to shape our behaviour,21 39 however, the findings of this review suggest that in the case of children aged 8 years and less, distal factors such as parental behaviours, and the home environment can be more influential in shaping their behaviour.

The majority of studies in this review reported a positive association between the child’s age and their mobile screen media use. Older children were more likely to use mobile screen media devices compared with their younger counterparts. This finding is consistent with a systematic review of traditional screen time use among children 3 years and younger.17 Potential reasons for increased mobile screen media use with increasing age include: greater access/ownership of these devices; decreased parental control and media use rules; and greater skills as a child ages.40 41 Studies have found that parents tend to set more rules regarding screen time for younger children40 and report that supervising the use of these devices becomes more difficult as the age of children increases.7 This suggests childhood screen habits are reflected in adolescence and adulthood,8 and highlights the importance of managing mobile screen media use with younger children.

Higher mobile screen media use by older children in the family has influence on younger siblings. One study in the review reported households with more than one child used screen devices (both fixed and mobile screens) more frequently,36 which could be the result of younger children observing and modelling the behaviour of older siblings. Of interest, role modelling either by parents or older siblings has been used effectively in other areas to influence children’s behaviours,42 43 and could be an important strategy to decrease young children’s mobile media use.

This review found no association between child’s BMI and mobile screen media use. In contrast to this, a prospective study carried out in Finland reported that the increase in screen time during a 2-year follow-up period was smaller for children who had lower BMI at 13 months,44 while a previous research reported a positive association between TV viewing and being overweight but no association with computer use.45

Mixed results in regard to parental age and children’s mobile screen media use were reported. Three studies reported no association,1 27 33 while Wu et al found a negative association, indicating higher any media use among children of younger parents.36 A prospective study carried out in Finland has also found that the increase in the screen time was smaller when the mother was younger44 while previous systematic reviews on traditional media have reported an unclear association with their use and parental age.17–19 Parents who used mobile screen media were more likely to have children who used these devices and for a longer time.1 27 30 31 Furthermore, children of families who watch more TV are more likely to engage in higher screen viewing.17 19 46–48 Therefore, children of parents with higher mobile screen media use may be more likely to have higher use due to parent role modelling, thus being considered ‘normal behaviour’.49

Parent-child co-use of mobile screen media was highest for children younger than 2 years and decreased as the child aged.1 This may be due to younger children being less able to manipulate technology or inability to unlock password-protected devices and therefore requiring parental support to operate the device. Furthermore, younger children may spend more time at home with their parents, providing more opportunities for parent-child co-use.1 It should be noted that decreased co-use with increasing age of children reduces monitoring opportunities for parents.

The review found that children of stay-at-home parents had higher mobile screen media use.36 This suggests parents could be more engaged in screen viewing, providing a supportive environment for mobile screen media use for their children. Conversely, self-reported data from employed parents might under-report their children’s media use. Other systematic reviews focusing on children’s traditional screen time report that parental occupation is rarely studied, thus it is difficult to draw any specific conclusion.17 18 This is an area worthy of future research as parents working long hours or bringing their work home may minimise monitoring of children’s mobile screen media habits.

Mixed associations were found between family income and children’s mobile screen media use. Children from high-income families were using touch screens for longer durations than those from low-income families,30 which may be due to greater ownership and access to touch screen devices in these households. Conversely, a study on electronic media use (both fixed and mobile screens) concluded no association between family income and children’s screen time,50 while the number of media devices at home and in the child’s bedroom was positively associated with mobile screen media use,37 which is consistent with other studies.51 52 It seems that when these devices are in the bedroom, children have easy access and autonomy to use them, ultimately leading to increased use.51 This also holds true in the case of traditional media devices such as televisions and computers.45 51

Use of mobile screen media devices was higher among children whose parents believed in their pacifying effects, with parents using these devices as behavioural regulation tools to secure free time or when busy with household chores or shopping.4 10 16 53 54 Studies have shown that although parents are aware of the negative effects of using these devices for longer durations, many of them are high screen users themselves and are comfortable allowing their children to use these devices.49 55 Parents are concerned about their children going online, but research indicates they are less concerned about their children using a smartphone or watching television.7

Methodological limitations of studies reviewed

A strength of this study was the protocol paper that guided the methodology of the review,22 however, we did not search the grey literature or include qualitative studies. A major limitation of the studies reviewed was the lack of objective measures to assess children’s media use with parental proxy reports used in all of the studies. This approach may underestimate or overestimate true exposure because of recall bias, social desirability bias or simply not being aware of screen viewing behaviours.8 In addition, only one study tested reliability and validity of their instrument36 while others either relied on previously used questionnaires with unknown validity/reliability estimates. The review was also challenging due to the lack of standardised terminology when researching mobile media screen use research, as well as the lack of standardised reporting of findings by age. The AAP15 recommendations for children’s screen media use the age categories: (A) younger than 18 months, (B) 18–24 months, (C) 2–5 years, and (D) 6 and older. However, the studies in this review often reported across these age groups or failed to provide detailed information of the target group’s age when undertaking analysis. Finally, meta-analysis was not conducted due to the study findings being segregated across different mobile screen media types, making the findings largely descriptive. Future research in this area should consider undertaking randomised controlled trials with larger sample sizes and (standardised) study outcomes that can be aggregated and compared.

Conclusion

Despite the rapid growth in mobile technologies, this review on the correlates of mobile screen media use among children 0–8 years identified limited but increasing research being undertaken in this area. The review found that correlates such as child’s age and media skills, parental media use and access to media devices at home appeared to impact on determining the mobile screen media use. Screen media use can certainly enhance life experiences and learnings, however, it is important that it is used appropriately and the family environment can play a key role in maintaining a ‘healthy media diet’. To better understand the impact of environmental factors on children’s mobile screen media and stimulate discussion, we need to better understand the role of parental rules; the use of mobile screen devices as behavioural regulation tools; and the role of parents and older siblings as role models. To achieve this, we need valid and reliable objective measures such as a smartphone/tablet applications that measure the time the screen is on,56 use of standardised terminology and the reporting of findings against specific age groups. These approaches will support a better understanding of the correlates of mobile screen media use and traditional screen media use when undertaking future research.

Acknowledgments

We would like to acknowledge the support of Public Health faculty librarian of Curtin University, Diana Blackwood, for her guidance during the database searching stage.

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Footnotes

  • Contributors SP, JL and JJ jointly conceived and designed the study. SP was responsible for searching the literature, screening the papers, working on design, critically reviewing the papers and drafting the manuscript. JJ provided overall supervision for the study, finalised methodology, screening of full text, quality assessment, and edited the manuscript. NS was involved in searching the database, initial screening of title and abstracts, and revised the manuscript. JL contributed to design, screening of full text, quality assessment, and organised and revised the manuscript. All authors have read and approved the final version of manuscript.

  • Competing interests None declared.

  • Ethics approval Since this systematic review uses already published, deidentified data, it is hence exempt from the ethics approval process. It does not involve any contact with the human participants and has not collected any primary data.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement No additional data.

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