Background and methodology Despite widespread availability of contraceptives and increasing service provision in the UK, rates of teenage pregnancy remain a concern. It has been suggested that young people face particular obstacles in accessing services, leading to a need for specialist provision. This systematic review examined the literature reporting views of service providers and young people. Data were synthesised in order to develop key themes to inform the development of contraceptive services for this population.
Results A total of 59 papers reporting studies carried out within the UK were included. Forty-five of these provided qualitative or mixed method data and 14 reported survey findings. Seven key themes were identified: perceptions of services; accessibility; embarrassment; anonymity and confidentiality; the clinic environment; the consultation; and service organisation.
Conclusions This review suggests that the most significant concern for young people is the preservation of anonymity and confidentiality. There seems to be a need for young people to be given greater assurances about this, with process and environmental changes suggested. The fear of staff being critical or unfriendly also presents a considerable obstacle to some young people. Issues of service accessibility – such as convenience of location and opening hours – are also highlighted, with lifestyle factors and restrictions on where under-18s can go suggested as important aspects. The review suggests that varying preferences among young people with regard to which service to access requires choice to be preserved and, where possible, extended. This requires services to work effectively together to consider provision across a locality.
- Received March 18, 2010.
- Accepted July 15, 2010.
- Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions
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Young people in the UK are experiencing sexual intercourse at an increasingly younger age.1 However, it has been reported that not all young people use contraceptives at first intercourse or consistently.2 This limited usage is despite widespread availability of contraceptives across the country, with free and confidential services provided by general practitioners (GPs), family planning clinics (FPCs), local drop-in facilities, school nurses in some areas and specialist services such as Brook Advisory Centres.
Key message points
▶ Further work is required to assure young people regarding the confidentiality of services.
▶ Services should consider issues of accessibility, environment and processes to encourage uptake among young people.
▶ Variation in preferences among young people requires choice to be available regarding which service to access.
While it has been reported that around 80% of women receive contraceptive services from their GP,3 studies have indicated that teenagers find consulting with their GP difficult.4 In response to this, the range of sexual health services specifically for young people has increased, driven by government policy aiming at reducing concerning rates of teenage pregnancy and sexually transmitted infections.5 6 It has been argued that contraceptive services need to be specifically targeted, as young people face particular obstacles in accessing health care.7 It is suggested that these new specialist services should be planned around patient need, and involve users in service design.8 New youth-orientated services are increasingly evident such as the ‘One-Stop Shop’,9 young people's ‘Help Centre’10 and sexual health clinics based in secondary schools.11 There has also been an extension of the services provided by community pharmacists, with the advent of emergency oral hormonal contraception (EHC) being available ‘over the counter’.
A recent examination of services for young people12 linked different types of delivery to varying success rates for reducing teenage pregnancy across the UK. The report highlighted concerns regarding a considerable disparity in provision available in different areas of the country. Papers providing evaluations of new initiatives have suggested that specifically designated youth services can increase clinic attendance rates.10 However, some studies have reported that this seems to be mainly among young women,13 14 with limited success in attracting young people from high-risk groups.15 It has been highlighted that there are challenges associated with user involvement in service planning and delivery; such as the need to ensure representation from a wide variety of backgrounds, and support for their participation.16 French et al.9 have suggested that more evidence is required on the impact and appropriateness of different service delivery models for young people.
This study examined research reporting the views of young people and service providers in the UK. The full remit of the work undertaken was an examination of the knowledge and perceptions of contraception among young people, together with provider and user views of services and service delivery. This paper reports the data regarding views on contraceptive services.
The review team drew on National Institute for Health and Clinical Excellence (NICE) search methods17 to use an approach based on several smaller, more targeted searches to identify evidence, rather than a large, single search. In this method retrieved citations are used to identify useful terms to inform further searches (see Appendix 1 for a sample search strategy). Studies were excluded when they were conducted with people aged 25 years or older. Papers that contained data for both under-25s and over-25s were included if 50% of participants were aged 25 years or younger. There was no cut-off limit for the youngest age of inclusion. The review considered contraceptive services provided in clinical and non-clinical locations, however it excluded views of the school curriculum. The search was restricted by date (1995–2008) and by limiting the search to humans (to avoid animal studies relating to contraception).
Relevant literature was identified via free-text searching of electronic databases (see Appendix 2) and citation searching of included articles (using Web of Science Cited Reference search and Google Scholar). Also, by sifting the reference lists of included articles; sifting the reference lists of relevant systematic reviews; searching of websites for grey literature; and consulting an expert group.
The results were downloaded into Reference Manager for sifting at title and abstract level. Following this sifting, studies for potential inclusion were obtained for full paper examination and data extraction. The process is illustrated in the flowchart in Figure 1. Inclusions and exclusions were checked by a second reviewer, and where consensus could not be reached, by a third reviewer. Data relating to the research question, theoretical approach, data collection, data analysis, population, key findings and study limitations were extracted.
Box 1 Quality indicators for qualitative studies
Is a qualitative approach appropriate?
Is the study clear in what is seeks to do?
How defensible is the research design?
How well was the data collection carried out?
Is the role of the researcher clearly described?
Is the context clearly described?
Were the methods reliable?
Is the data analysis sufficiently rigorous?
Are the data rich?
Is the analysis reliable?
Are the findings credible?
Are the findings relevant?
Are the conclusions adequate?
How clear and coherent is the reporting of ethics?
All or most of the criteria fulfilled = high quality
Many of the criteria fulfilled = good quality
Few of the criteria fulfilled = poor quality
While there is currently no NICE framework to assess survey papers, quality indicators for survey papers noted were: sample size; return rates; whether the questionnaire was piloted; the appropriateness of study conclusions; and relevance.
The review question concerned views of services rather than a more standard systematic review, which considers the effectiveness of an intervention and may combine outcomes numerically.18 In order to analyse the data we drew on the principles of qualitative meta-synthesis,19 and methods of thematic synthesis.20 In this approach data from each paper are extracted to establish core themes. These themes are then further analysed and synthesised using a process of comparison and contrast to further develop key concepts. Unlike effectiveness reviews this method does not compare data by measured outcome, and unlike meta-analysis it does not weight findings according to sample size or study design. The method integrates data across all the papers to develop a deeper understanding of views or perceptions.
The searches identified 59 papers that met the inclusion criteria from a database of 839 citations. Forty-five papers reported data from qualitative or mixed method studies and 14 reported data from surveys (Table 1). Using NICE criteria, eight papers were rated as high quality, 26 were rated as good quality and 11 papers were rated as poor quality. Analysis and synthesis of these data suggested a number of themes relating to the delivery of contraceptive services to young people (Box 2).
Box 2 Themes in the data
Perceptions of particular services
Accessibility of services
Anonymity and confidentiality
The clinic environment
Perceptions of particular services
Perceptions of FPCs and sexual health clinics and pharmacies were reported in five papers.10 21,–,24 Study participants' ages were in the range 14–25 years. The data suggested the importance of the name of a service, with a perception among some young people that ‘clinic’ implies a place where only girls go21 23 and that ‘family planning’ means a service for older couples23 or where older married women go.24
Views of pharmacy services were reported in three papers, with generally positive perceptions expressed. Pharmacy services were described as being helpful,25 as being easy to visit26 and being less regulated than GP services or FPCs.27
Five papers suggested evidence of some concerns regarding services provided by GPs. A perception that the service lacks confidentiality was reported,28 particularly among young people of African and Indian ethnicity, although not among non-Indian Asians.29 Concerns regarding GP services were also voiced in rural communities.23 Another negative perception of GP services mentioned in one paper30 is the obstacle of getting past the surgery receptionist in order to make an appointment. In contrast to these negative perceptions, however, a study in a school-aged population31 indicated that concerns regarding GP surgeries are not universal. The findings from this paper were that views varied, with some young people having concerns about GP services in regard to information reaching their parents, whereas others report preferring a GP service to a school-based service.
Staff perceptions of particular services are reported in four papers.9 32,–,34 Mackie et al.32 described staff concerns that using premises that are not health service sites had drawbacks in terms of transporting drugs and a lack of client records on site. Participants in the Pitts et al. study33 echoed young people's concerns that the receptionist in a GP surgery could act as a barrier. Some of the GP participants in one study34 had negative views regarding the appropriateness of a pharmacy environment for EHC provision. One paper9 described positive perceptions of satellite and outreach services. In this paper staff highlighted that these services could be important stepping stones for young people into more mainstream services.
Accessibility of services
Eleven papers provided data regarding the importance of services being easy to access. Convenient opening hours, being in a preferred location, and fitting in with a young person's lifestyle are particular elements of accessibility reported.
Bissell and Anderson25 described women participants as finding pharmacy provision easy to access due to extended opening hours and weekend provision. These elements were echoed in another study,26 which similarly described greater accessibility in terms of convenient location, flexible opening hours and rapid consultation. Griffiths et al.29 described convenience as a key theme, with timings of sexual health clinics reportedly making them difficult to access. The importance of convenient opening hours was also highlighted in a survey7 suggesting that young people would prefer services to be open after school (71%, of respondents aged 11–18 years) or on Saturdays (49% of respondents). Older pupils were more likely to find after-school clinics (p=0.001) or lunchtime clinics (p=0.038) useful than younger ones.
These service user views regarding the importance of accessibility were reflected in papers that reported staff views. Three papers24 33 35 described staff as identifying easy access as important elements of a service. Three papers25 34 36 reported that staff as well as young people recognise that accessibility of pharmacy services is a benefit.
Location of service
Seven studies provided data on views of service location. Ingram and Salmon13 concluded that services should be in close proximity to the young person's home location. Further work by the same authors31 reported that school-aged participants emphasised the convenient location and ease of access of a school-based service. A survey study37 indicated that the proximity of a clinic was linked to greater use. In contrast to these papers, however, one study16 highlighted that the perception that young people prefer services near to their home may not always be the case. In this study of FPCs, new clients often used services near to a friend's house or to their school rather than their home, and tended to continue to use that clinic. French et al.28 similarly reported that closeness to home is not always preferred. They described varied views regarding location, with some young people preferring clinics outside their home locality to avoid being seen by people they know. Craig and Stanley38 highlighted that while venues should be accessible; they need to be convenient so that a young person can travel there without being reliant on a parent for transport.
Two studies described the need for services to be located in venues that fitted in with a young person's lifestyle. In one study28 some young people mentioned the benefits of services being located in town centres or locally to increase accessibility. Participants suggested outreach into venues that young people accessed such as hairdressers, nightclubs, snooker halls, fast food outlets, youth services, events, sports shops, music shops and churches. Another paper21 also described the importance of accessibility in terms of lifestyle and lack of age restrictions. In this study, young people described the lack of condom machines in female toilets, and inaccessibility of machines to young people unable to enter pubs or nightclubs. The authors suggested that machines should be located where 14–16-year-olds and 17–19-year-olds spend their free time.
Four papers highlighted that young people have varying preferences regarding service location.38,–,41 In a survey of pregnant young women's use of services, it is reported that 60% had opted to visit a GP clinic and 30% a FPC regarding contraception.39 One paper highlighted differences between young men and women with regard to service preferences.40 Studies in a rural area38 and among minority ethnic young people41 described the perception among some participants of having a lack of choice regarding which services they could access.
Studies reported varying views with regard to whether an appointment system or a drop-in service provides greater accessibility for young people. Ingram and Salmon13 suggested a drop-in service is more convenient. A survey of 11–18-year-olds7 reported that 62% would prefer a walk-in service. However, while these respondents valued the drop-in aspect, the study highlighted that 24% would not be prepared to wait longer than 15 minutes to be seen. Another survey42 suggested that 93% of young people (aged 16–24 years) would prefer to make appointments by telephone rather than in person.
Papers25 36 described staff perceptions that not needing to make an appointment at pharmacies for EHC was a key benefit for young people. Also, that a drop-in system in sexual health clinics is perceived as preferable by staff.43 Baraitser et al.16 reported that waiting times can be long in a clinic that does not have an appointment system, although staff perceived that the clinic was accessible despite this fact. Pitts et al.3 found that GPs perceive that having an appointment system is an advantage in terms of being available.
A recurrent theme within the data concerned the perception of embarrassment surrounding contraception and contraceptive services. Sixteen studies16 21 22 28 31 44,–,54 described young people's perceptions of embarrassment. One44 reported the reduction of embarrassment when women (GP patients) were given supplies of EHC, rather than having to seek a supply from a doctor when needed. Another45 highlighted staff concerns that supplying contraception should not make young clients feel embarrassed. A study by Sixsmith et al.21 described the embarrassment felt by young people when obtaining condoms. Baraitser et al.16 reported the embarrassment felt by 16–24-year-olds when giving personal details at a clinic reception desk. Salmon and Ingram31 found that half the participants in their study reported embarrassment at using a school-based service. Other studies of school-aged young people22 46–47 similarly emphasised the embarrassment felt when discussing contraceptive services. This embarrassment was described in papers reporting perceptions of young people up to 25 years of age28 48,–,50 including clients of a FPC.51
Stone and Ingham52 reported that 20–24% of women had felt embarrassed or scared to use a contraceptive service. Other survey studies indicated that 63% of females and 46% of males (age 15–16 years) would feel embarrassed by consulting their GP about contraception,53 and 66% of black and minority ethnic males would be prevented from attending a sexual health service because they experienced embarrassment.54
Anonymity and confidentiality
Nine papers reported the importance of a young person's identity remaining unknown when accessing services.21,–,25 28 29 38 55 The fear of being seen, being uncomfortable in case they were recognised by someone, and fear of their anonymity being compromised was described. In order to address these concerns there was the suggestion from study participants that they would prefer the use of numbers rather than names in a clinic situation,24 28 services where it is not possible to identify the reason for the visit,28 and waiting rooms separated by gender.28
The Powell55 study reported that telephone help lines, magazines, chat rooms or television were valued sources of information and advice due to their anonymity. Papers that described staff perceptions also echoed the importance of anonymity to young people.27 32 33 36
Confidentiality was often linked to anonymity by young people. Eleven studies identified the importance of perceived confidentiality.13 23 24 28 29 31 38 39 45 52 56,–,60 Young people described professionals having their name and address, or a personal file on them to be a concern, with some worried that staff would breach confidentiality either deliberately or by omission. One study52 reported that under-16-year-old women were the most likely to report concerns over confidentiality as a reason for delaying service use. Another study45 reported concerns at discussing sexual health matters at a youth club due to the noisy environment and proximity of other people. Another57 described the concerns of young Pakistani women regarding confidentiality from health professionals of the same background, and a second29 also reported particular concerns regarding confidentiality of a GP surgery among particular ethnic groups (African and Indian). Confidentiality concerns were most often reported in relation to GP surgeries23 28 29 56 59 61 although not exclusively so.31
Issues regarding confidentiality were raised in particular with regard to young people living in rural areas, where it was a small community and staff at clinics, surgeries or pharmacies may know the young person or their friends, or be friends with the parents of a young person.38 62 There were also fears in these localities that clinic reception staff with access to records would breach confidentiality.
A staff perspective on confidentiality is provided by Garside et al.63 who reported that 76% of GPs preferred parents to be informed when a young person consulted them about contraception. Other papers reporting data from staff highlighted that facilities not linked to schools may be perceived as having greater confidentiality43 and that schools varied with regard to their policies on confidentiality.64 One study described staff reports of women deliberately travelling to an unfamiliar neighbourhood to seek EHC in order to allay fears of lack of confidentiality at their local pharmacy25 together with staff concerns regarding a lack of privacy in the waiting area.32 In contrast, McCann et al. reported positive perceptions among school nurses and GP practice nurses that procedures regarding confidentiality were well managed and consistent.65
Anxiety underpins much of the data concerning young people's views regarding confidentiality and anonymity. Two papers specifically highlighted the anxiety felt by young people when accessing a service for the first time, and one paper reported anxiety in regard to EHC supplies. Baraitser et al.16 described the sense of relief and accomplishment felt by a young person following an appointment, and Lester and Allan22 highlighted the lack of confidence felt by young people attending a clinic. Fairhurst et al.44 described the easing of anxiety felt by young women who were provided with EHC in advance.
The clinic environment
Views regarding the clinic environment were outlined in six papers.11 13 16 23 31 43 Baraitser et al.16 reported that clients made more comments on the waiting room than any other topic in their evaluation of a family planning service. Young people disliked a clinical appearance, preferring instead a more homely and cosy space resembling a communal living space in a private home. Also, participants requested improved entertainment in the waiting area, with waiting being stressful and silent reportedly leading some people to leave before they were seen. Other papers described a welcoming and friendly,13 comfortable and relaxed,23 31 informal43 and congenial environment11 as being important to young people.
Respectful and non-judgemental staff
Twelve papers made reference to the value placed by young people on staff being respectful and non-judgemental.13 16 23 24 26 28 38 41 48 56 66 67 Baraitser et al.16 reported that young people were more likely to comment on the attitudes of staff than to make an assessment of their knowledge or technical competence. In the Folkes et al. study26 some participants had experience of negative encounters with professionals when they were seeking EHC, when they felt that they were being judged. The fear of being judged was described by young people in eight studies, with Mason66 concluding that staff needed to be more understanding of why girls wanted to have sex, and the suggestion from the Pearson and Pearson23 study that young people perceived that staff closer in age to themselves may have less disapproving beliefs. The Free et al.48 paper similarly described the perception of young people accessing EHC that they were being “told off”, and that more youthful staff would be less disapproving.
Chambers et al.68 sought the views of young people (aged 12–20 years) and health professionals, and found that both groups suggested that staff should be educated to be more sensitive in relating to young people. In other papers, young people reported that they were aware of the potential disapproval of adults towards them becoming sexually active, with concerns regarding what staff and other adults would think of them when accessing services.21 22 28 Concerns to preserve their image and social standing, and not lose their reputation or be stigmatised were also highlighted.23 38 49 Participants reported in one study13 that they would like to be treated as an adult and not made to feel ashamed.
Staff perceptions regarding their own and other staff attitudes towards young people were reported in four papers. One35 described staff views in an accident and emergency department that some medical staff could demonstrate a lack of sympathy for young people requesting EHC. In this study the author described some ambivalence in staff attitudes between being sympathetic and being judgemental towards adolescents. Pitts et al.33 also reported ambivalent emotions and language as regards teenage sexuality, suggesting some unease among sexual health service staff participants regarding the onset of sexual activity in young people. The authors concluded that there was a potential tension between the underlying attitude to young people's sexual behaviour and the need to help. Variation in attitudes among family planning service staff were described in one paper,16 and another43 described a perception among staff that accepting a young person's sexual status was key for professionals working in the area.
Building a relationship
Reeves et al.69 found that having staff who were “easy to talk to” rated among the most important aspects of a service for young people. Lester and Allan22 described young people as preferring someone who “got straight to the point”. Pearson and Pearson23 also suggested that brevity was important, with male study participants valuing minimal contact time with no personal questioning or counselling. Other positive aspects described are a professional, friendly, matter of fact approach and someone who shows understanding whom a young person could build a relationship with.49 50 55 French et al.28 explored views of ethnic minority young people, and described diversity regarding whether the ethnicity, age or gender of a staff member was considered important.
Staff views regarding key aspects of the consultation echo the importance of establishing a relationship with the young person.33 35 43 Bloxham43 described staff perceptions that familiarity with a young person was influential, and reported the view that youth and community workers establish a different kind of relationship with young people from other professionals such as teachers.
Five papers reported staff concerns regarding limited resources for contraceptive services.9 36 63 64 Staff in the French et al. study9 voiced concerns that commissioning priorities around sexual health including both contraception and GUM were patchy. Hoggart64 reported that staff in particular perceived the restrictions of geographically limited initiatives.
Papers28 31 41 64 70 described concerns regarding the success of working between different agencies delivering services. Issues raised were: the need for improved connection between agencies; the importance of having an integrated strategy;64 the need for leadership;70 and the need for collaborative networks with clear signposting and consistent messages between services.28 There was also evidence of concerns regarding role limitations or confusion among some staff.41 70 Salmon and Ingram31 reported that while joint working between agencies had been a particularly successful aspect of the school service innovation they evaluated, that there was still a need for links between the service and other community agencies to be improved.
Lack of training for staff was perceived as a barrier to high-quality service provision by participants in two studies.64 70 A lack of knowledge or confusion regarding all available methods was described by pharmacists71 72 and other health professionals,73 although early studies of provision may now have less relevance. A lack of training was reported among teachers43 and among staff trained in GUM, whose role had been extended to provide wider contraceptive services.9
This study examined the literature reporting views of young people and staff regarding contraceptive service delivery. It highlights seven key areas to consider in design and implementation of services for young people.
This review emphasises the importance of accessibility of services in terms of a convenient location and opening hours. The papers reported a slightly greater percentage of young people surveyed opting for a ‘drop-in’-type service, although concerns regarding long waits were evident, and this choice was far from universal. In terms of location, the need to further consider lifestyle factors and restrictions on where under-18s can go seemed significant in decisions regarding where to place contraceptive vending machines.
An examination of perceptions of services indicates generally positive views regarding pharmacy provision among young people, in contrast to some staff concerns regarding the appropriateness of this location. The name of a service may be a key consideration, with the suggestion that ‘family planning’ and ‘clinic’ can be perceived as lacking relevance for some young people.
This review suggests that the most significant concern for young people is the preservation of anonymity and confidentiality when accessing services. There seems a need for young people to be given greater reassurances about this. Aspects of services that could be considered further are the use of numbers rather than names in public areas, and ensuring the reason for a visit remains confidential when making an appointment and on arrival. The appearance of the clinic was reported as an influential factor, with the waiting room playing an important role in whether a young person is prepared to remain until they can be seen. The use of gender-specific waiting areas and video entertainment was suggested as potentially enhancing the environment.
Another aspect of service delivery where young people seem to require further reassurances relates to the attitude of staff and content of the consultation. It was reported that young people valued staff members who have a respectful and non-judgemental attitude towards them, with the fear of staff being critical or unfriendly seen as presenting a considerable obstacle to some young people. This highlights the importance of skilled staff, a factor also emphasised in a recent review of reviews73 identifying facilitators of effective sex and relationship interventions.
Young people's embarrassment at accessing contraceptive provision seems the most significant barrier for services to overcome. Embarrassment also underpins the fears regarding breaches of confidentiality and concerns regarding preserving anonymity. Young people are experiencing sexual intercourse earlier1 and younger age groups are reportedly where intervention is most effectively targeted,74 yet this is the group that is most concerned about confidentiality.52 There seems a need for the design and delivery of services to have a key focus on reducing embarrassment, by paying attention to and publicising systems for maintaining confidentiality and anonymity, and also by taking steps to make young people more aware of the non-judgemental stance of staff.
This review highlights the diversity in preferences among young people regarding which service/s they wish to access and where and how they should operate. This suggests that while new initiatives may be welcomed, the preservation or extension of choice remains paramount. The divergent views regarding general practice consultations have been described, with some young people expressing significant concerns regarding confidentiality, whereas for others their GP has been the service of choice. Some young people wish to access a service near to their home, but preservation of anonymity leads others to choose services away from their home area. Similarly, appointment-free options may be preferred by some, but not others.
While the review was able to identify a large body of UK evidence, few of the included papers used more than a single source of qualitative data. Although there is considerable debate regarding quality assessment of qualitative studies, the use of and comparison of data from multiple methods (triangulation) is often considered to add strength/depth to the findings and would enhance the evidence base. Papers reporting mixed method data often missed the opportunity to compare and contrast findings, tending to focus on the quantitative data and adding only a small number of examples of quotations. The survey studies tended to use untested instruments, with few details reported regarding their development. The use of a standard survey tool across services would be valuable to enable direct comparisons to be made.
The examination of published evidence inevitably captures past practice, and this review included studies published over the last 15 years. Future reviews will be able to assess the impact of guidelines such as the ‘You're Welcome’ criteria75 and changes to professional practice. This review was limited by considering solely UK evidence. A review comparing practice between countries may offer additional insights.
The findings of this review support and provide additional evidence to underpin the ‘You're Welcome’ quality criteria issued by the Department of Health.74 This best practice guidance similarly highlights accessibility, confidentiality, the environment and trained staff working together as features of an effective service. The findings reinforce the need for services to examine their approach to confidentiality, and consider any measures that can be taken to increase anonymity.
While this review sought to examine perceptions of contraceptive services rather than assess the effectiveness of delivery, the views of users are significant in identifying where practice may be enhanced. The work suggests that a key consideration within each local area should be the availability of choice in where and how to obtain contraception. This requires services to work effectively together to consider provision across a locality. Also, in efforts to evaluate services, the variability among young people regarding the type and location of service that they prefer to access should be borne in mind. While new service initiatives for young people are to be welcomed, it seems that there is no ‘one size fits all’ option.
- Received March 18, 2010.
- Accepted July 15, 2010.
Funding This review was funded by the National Institute for Health and Clinical Excellence (NICE) for the purposes of informing public health guidance. The interpretation, analysis and views expressed are those of the authors and not necessarily those of NICE.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
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