Research and analysis

Population screening: review of interventions to improve participation among underserved groups

Published 27 January 2022

1. Summary

1.1 What was already known

Participation in screening varies both within and between screening programmes.

Groups at higher risk of conditions being screened for are often less likely to participate in screening^{[footnote 1] [footnote 2]}.

Little is known about which specific interventions improve screening uptake among underserved groups.

1.2 What this study adds

This review identified several mostly reminder-based interventions for which there was good evidence of improvement in uptake of young person and adult (YPA) screening programmes among underserved groups in the UK.

It found very little evidence (only 4 research trials) relating to interventions to reduce inequalities in participation in antenatal screening programmes and none for newborn screening programmes.

It concluded that areas where further research is needed in this area include:

• participation at other stages of the YPA screening pathways
• non-cancer screening programmes
• less-researched underserved groups
• whether interventions have different effects in different groups
• all stages of the antenatal and newborn (ANNB) screening programme pathways

2. Results

2.1 YPA programmes

Thirty six trials relating to YPA screening programmes were identified, reporting 193 comparisons of screening uptake within underserved groups. Most of the evidence related to uptake of cancer screening programmes and by underserved groups defined by socioeconomic status, ethnicity, age, sex, and screening history.

There was strong and consistent evidence in favour of:

• reminders that include a timed appointment
• GP letters for non-responders
• human papillomavirus (HPV) self-test kits for cervical screening programme non-responders (an intervention that is being trialled in selected sites in England)

There was some evidence favouring:

• annual reminders for non-responders
• pre-appointment reminders by post or text message

There was weaker or unconfirmed evidence favouring:

• timed office hours appointments with an offer to switch to out-of-hours
• GP letters near the time of invitation
• GP endorsed invitations
• enhanced reminder letters
• telephone reminders for non-responders
• a psychoeducational booklet

There was little or no evidence favouring:

• nurse or link worker telephone calls or home visits
• pre-notification letters in cervical screening
• tailored invitations referencing screening history
• simplified leaflets
• narrative leaflets
• anticipated regret questions
• planning tools addressing barriers to screening

There was reasonably strong evidence from a single trial of diabetic eye screening that financial incentives do not improve uptake.

2.2 ANNB programmes

The focus of the ANNB report was participation in screening measured as acceptance of the offer of screening, rather than uptake of screening.

One trial found by the systematic review provided plausible evidence that earlier initiation of sickle cell and thalassaemia (SCT) screening by GPs reduces the time to completion of screening.

Of 2 trials in Down’s syndrome screening, one focused on informed choice, and reported no difference between groups provided with decision aids in written or video format compared to a standard patient information leaflet. The other trial reported that video information improved knowledge scores.

A trial in HIV screening in pregnancy reported no overall evidence favouring combining a leaflet relating to HIV screening with information on other antenatal blood tests or the addition of a comprehensive midwife discussion relating to these.

3. Background

Variation in participation in screening programmes exists both within and between national screening programmes. Moreover, groups at higher risk of the condition targeted by screening tend to be less likely to participate^{[footnote 1] [footnote 2]}. This inequality in screening participation can be due to barriers that make it harder for some groups of people to engage with screening services. Screening inequalities can occur at any point along the screening pathway and barriers that persist once a person has started screening may result in some people being unable to maximise the benefits of screening.

Public Health England (PHE) committed to reducing inequalities in screening in the national screening inequalities strategy.

PHE commissioned this systematic review in order to support and encourage actions to address inequalities. The review looked at interventions which may improve participation at any stage in the screening pathway by underserved population groups in national screening programmes in the UK. This follows an earlier rapid review of a similar question for cancer screening^{[footnote 3]}.

4. Methodology

The systematic review explored interventions that improve participation by underserved groups in screening programmes in the UK.

Data sources were: Medline, EMBASE, Cochrane, CINAHL, HMIC, and PsycINFO to 10 October 2019.

Randomised trials in national screening programmes in the UK were included if they reported results related to participation in screening for underserved groups at any stage of the screening pathway. The primary outcome for YPA programmes considered in the review was uptake of screening. This was chosen as the primary outcome as it is what most of the studies report. Secondary outcomes were any outcomes related to cohort identification, patient information about screening, access to screening and to treatment, onward referral, disease outcomes and preference to opt out of screening.

Underserved groups were defined as:

• those experiencing socioeconomic deprivation
• those with any of the protected characteristics described in the UK 2010 Equality Act
• those not registered with a General Practitioner (GP)
• homeless people
• rough sleepers
• asylum seekers
• gypsy and traveller groups
• sex workers
• those in prison
• those experiencing severe and enduring mental health problems, drug or alcohol harm issues or communication difficulties

In addition, first-time invitees were included as an underserved group because younger age groups were considered underserved in every screening programme and because this group is of interest in its own right.

Non-responders were included as a useful proxy for underserved groups, and were categorised in 3 groups: recent non-responders who had missed a recent screening invitation and were at the reminder stage, previous non-responders who had not participated in previous screening rounds, and long-term non-responders who had not participated in multiple previous screening rounds.

Only UK trials were included because of the potential for differences in screening programmes, health services and underserved groups to substantially complicate interpretation of non-UK trials.

5. Gaps in the evidence

5.1 Non-cancer YPA screening programmes

All but one of the trials included in the review related to cancer screening programmes, with one for diabetic eye screening (DES) and none for abdominal aortic aneurysm (AAA) screening. As AAA screening has some structural similarities with bowel scope screening, being a one-time screen of older adults, the evidence in favour of annual reminders for bowel scope screening provided a useful hypothesis for AAA screening and would be worth investigating in this context. There may also be enough similarity between the screening processes for breast screening and cervical screening to prompt trials of interventions in one screening programme which have been shown to work well in another. Other interventions for which there was the strongest evidence in cancer screening programmes could also be considered as a priority for testing in the DES and AAA programmes.

5.2 Underserved groups that are more difficult to engage in research

Most of the evidence identified for underserved groups related to socioeconomic disadvantage, age, gender and previous non-response to invitations. It is important to also investigate interventions that would improve screening uptake in other groups that are more difficult to engage but also often at high risk of the condition being targeted by screening, such as those not registered with a GP, homeless people, rough sleepers, asylum seekers, gypsy and traveller groups, sex workers, those in prison, those experiencing severe and enduring mental health problems, people with drug or alcohol harm issues or communication difficulties and those with other protected characteristics described in the 2010 Equality Act.

Difficulties in engaging these groups would need to be considered in designing the trials. It is also important that larger trials have the power to investigate if interventions are more or less effective in underserved groups compared to the screening population as a whole.

5.3 Other aspects of screening participation

Screening inequalities can occur at multiple points in the screening pathway whereas all the evidence identified by the systematic review for YPA screening programmes related to screening test uptake. It is important to understand the inequalities in general knowledge and attitudes about screening and informed choice before receiving an invitation for screening as this is likely to be crucial in the decision to participate (Young 2018 ^{[footnote 4]}).

Further along the pathway, a high proportion of people with a positive screening result typically go on to receive diagnostic tests and treatment. It is not completely clear which population groups are less likely to complete the screening pathway or why (Dalton 2018 ^{[footnote 5]} Plumb 2017 ^{[footnote 6]}). It is plausible that people who face barriers at one stage in the screening pathway will also face barriers at other stages. Designing trials to examine this can be complex, because of the confounding effects of the questionnaires used to assess screening knowledge, attitudes and informed choice and because of the large numbers required and the need for informed consent for trials relating to diagnosis and treatment. However, improvements at all stages of the screening pathway are important if screening inequalities and the burden of diseases that are being targeted by screening are to be reduced.

5.4 ANNB screening programmes

Evidence identified by the review in relation to underserved groups and ANNB screening was very limited.

Although some information was available in relation to age, ethnicity, employment, education level, housing tenure and socioeconomic status, this was limited in nature and no evidence was identified for the many other groups for which it was sought, including:

• those with other protected characteristics described in the 2010 Equality Act
• those not registered with a GP
• homeless people, rough sleepers, asylum seekers, gypsy and traveller groups
• sex workers, those in prison, and those experiencing severe and enduring mental health problems, drug or alcohol harm issues or communication difficulties.

6. References

1. Whitehead M. The concepts and principles of equity and health. Int J Health Serv Plan Adm Eval 1992; 22: 429–445. ↩ ↩²

2. Health Equity in England: The Marmot Review 10 Years On. The Health Foundation, (accessed 18 July 2020). ↩ ↩²

3. Duffy SW, Myles JP, Maroni R, et al. Rapid review of evaluation of interventions to improve participation in cancer screening services. J Med Screen 2017; 24: 127–145. ↩

4. Young B, Bedford L, Kendrick D, Vedhara K, Robertson JFR, das Nair R. Factors influencing the decision to attend screening for cancer in the UK: a meta-ethnography of qualitative research. Journal of Public Health 2018, Vol. 40, No. 2, pp. 315–339 ↩

5. Dalton A. Incomplete diagnostic follow-up after a positive colorectal cancer screening test: a systematic review. Journal of Public Health 2018, Vol. 40, No. 1, pp. e46–e5887. ↩

6. Plumb A, Ghanouni A , Rainbow S ,Djedovic N , Marshall S , Stein J, Taylor S, Halligan S, Lyratzopoulos G ,von Wagner C. Patient factors associated with non-attendance at colonoscopy after a positive screening faecal occult blood test J Med Screen 2017 Mar;24(1):12-19 ↩