Sample characteristics

In September 2020, the CPRD Aurum dataset included 13.1 million active patients in England, registered at 1309 different practices. 1.71 million were eligible for bowel screening, 1.34 million were eligible for breast screening and 2.50 million were eligible for cervical screening. One hundred and twenty-seven thousand one hundred and forty-two (127,142) adults had a recorded diagnosis of SMI, 10.31 million had a recorded ethnicity, 11.42 million had linked area-based deprivation data, 3.41 million were current smokers, and 421,161 had a BMI greater than 30 (sample characteristics vary according to the eligibility of individuals for each programme and are presented in Tables 2–4).

Participation in bowel, breast and cervical screening by people with SMI

Overall, participation was lower among adults with SMI for bowel, breast and cervical screening (see Table 1). The largest differences in participation, between people with and without SMI, were observed for bowel cancer screening (42.11% vs. 58.89%; aOR: 0.57, 95% CI: 0.56–0.59; p < 0.001), followed by breast (48.33% vs. 60.44%; aOR: 0.68, 95% CI: 0.66–0.70; p < 0.001) and cervical (64.15% vs. 69.72%; aOR: 0.78, 95% CI: 0.76–0.80; p < 0.001, respectively; Table 1).

Table 1 Cancer screening participation by SMI status and SMI subgroup (unadjusted and adjusted models).

When broken down by SMI group, participation in all three programmes was lowest for people with schizophrenia, followed by people with other psychoses and bipolar disorder (see Table 1). When assessed using multivariate regression, participation for all three programmes was significantly lower for those with schizophrenia, compared to those with no SMI (Bowel: 33.50% vs. 58.89%; aOR: 0.43, 95% CI: 0.41–0.45; p < 0.001; Breast: 42.02% vs. 60.44%; aOR: 0.58, 95% CI: 0.54–0.61; p < 0.001; Cervical: 54.88% vs. 69.72%; aOR: 0.55, 95% CI: 0.52–0.58; p < 0.001; Table 1). The same was true for those with other psychoses, with participation in all three programmes being significantly lower, when compared with those without SMI (Bowel: 41.97% vs. 58.89%; aOR: 0.57, 95% CI: 0.54–0.60; p < 0.001; Breast: 45.57% vs. 60.44%; aOR: 0.62, 95% CI: 0.59–0.66; p < 0.001; Cervical: 61.98% vs. 69.72%; aOR: 0.73, 95% CI: 0.70–0.76; p < 0.001; Table 1). Results were slightly different for people with bipolar disorder, however. Indeed, while participation was significantly lower for these individuals, when compared to those without SMI, for bowel and breast cancer screening (Bowel: 49.94% vs. 58.89%; aOR: 0.73, 95% CI: 0.70–0.77; p < 0.001; Breast: 54.35% vs. 60.44%; aOR: 0.81, 95% CI: 0.78–0.85; p < 0.001), it was not significantly different, between populations, for cervical screening (69.69% vs. 69.72%; aOR: 0.97, 95% CI: 0.93, 1.00; p > 0.05; Table 1).

Variation in participation in bowel, breast and cervical screening by people with SMI

Subgroup analyses revealed that participation in all three programmes was universally lower among people with SMI, compared to people without SMI (i.e. when stratified by age, sex, ethnicity, geographic region, area-level deprivation, BMI and smoking status; all p-values <0.05; see Tables 2–4). The only exceptions to this were participation in cervical screening, between women with and without SMI, aged 25–29 years, and participation in cervical screening between women, with and without SMI, from ‘Other’ ethnic groups (both P’s > 0.05; see Table 4).

Table 2 Variation in Bowel cancer screening participation, for adults with and without SMIs, by demographic characteristic, smoking status and BMI.Table 3 Variation in breast cancer screening participation, for adults with and without SMIs, by demographic characteristic, smoking status and BMI.Table 4 Variation in cervical cancer screening participation, for adults with and without SMIs, by demographic characteristic, smoking status and BMI.Age

Inequalities in bowel cancer screening participation, between people with and without SMI, increased with age (the mean difference in participation between people with and without SMI increased from 12.1 percentage points at ages 60–64 [36.60% vs. 48.70%; aOR: 0.68, 95% CI: 0.65, 0.71], to 19.5 percentage points at ages 70–74 years [46.97% vs. 66.42%; aOR: 0.50, 95% CI: 0.47, 0.52]).

Patterns were similar for cervical screening, with inequalities in participation increasing with age (the mean difference in participation, between people with and without SMI, increased from 0.29 percentage points at ages 25–29 years [57.59% vs. 57.30%; aOR: 0.92, 95% CI: 0.84, 1.02], to 7.6 percentage points at ages 60–64 years [56.53% vs. 64.13%; aOR: 0.76, 95% CI: 0.71, 0.81]).

Patterns were slightly different for breast cancer screening, with differences in participation remaining relatively stable with age (the mean difference in participation, between people with and without a SMI, increased from 10.1 percentage points at ages 50–54 [40.88% vs. 51.03%; aOR: 0.74, 95% CI: 0.70, 078], to 11.3 percentage points at ages 70–74 years [53.36% vs. 64.69%; aOR: 0.70, 95% CI: 0.60, 0.82]).

Sex

Inequalities in bowel cancer screening participation, between people with and without SMI, were similar for both sexes (the mean difference in participation between men with and without SMI was 16.5 percentage points [39.14% vs. 56.48%; aOR: 0.57, 95% CI: 0.55, 0.59]; the mean difference in participation between women with and without SMI was also 16.5 percentage points [44.74% vs. 61.26%; aOR: 0.58, 95% CI: 0.55, 0.60]).

Men with SMI were notably less likely to participate in bowel cancer screening than women with SMI (39.14% vs. 44.74%).

Ethnicity

Participation by adults of an ethnic minority background was notably lower for all three screening programmes and was particularly low for those of an ethnic minority group who had SMI (see Tables 2–4). For bowel cancer screening, participation was lowest among Black adults (34.86% and 47.23% for those with and without SMI, respectively) and highest among White adults (44.01% and 62.23% for those with and without SMI, respectively). For breast screening, similarly, participation was also lowest for Black women (38.68% and 44.95% for those with and without SMI, respectively) and highest for White women (50.53% and 62.98% for those with and without SMI, respectively). Results were different for cervical screening, with participation being lowest among Asian women within the SMI cohort, and Other women among those without SMI (participation was 57.92% and 59.68%, respectively). Again, participation in cervical screening was highest among White women (participation was 65.95% and 72.93% among those with and without SMI, respectively).

After adjusting for the impact of other factors, adults with SMI, across all ethnic groups, show significantly lower participation for all three cancer screening programmes. Adults with SMI from White ethnic groups show higher screening participation than their peers with SMI from other ethnic groups, but the difference in participation, between those with and without SMI, was consistently wider for White adults than any other ethnic group. For bowel cancer screening, there was an 18 percentage points difference in participation between White adults, with and without SMI (44.01% vs. 62.23%; aOR: 0.56, 95% CI: 0.54, 0.58), compared to an 11 percentage points difference for those of a Mixed ethnic background (39.49% vs. 50.99% [aOR: 0.71, 95% CI: 0.56, 0.92])—the ethnic group with the smallest difference in participation, between those with and without SMI. Patterns were slightly different for breast and cervical screening with the absolute differences between adults with and without SMI for each ethnic group smaller. For breast cancer, the greatest difference in participation, between those with and without SMI, remained between White adults (50.53% vs. 62.98% [aOR: 0.67, 95% CI: 0.65, 0.69]), and the smallest being between those of Other ethnicity (43.70% vs. 46.41% [aOR: 0.87, 95% CI: 0.61, 1.23]). Similar to breast, for cervical screening, the greatest difference in participation, between those with and without SMI, was among White adults (65.95% vs. 72.93% [aOR: 0.78, 95% CI: 0.75, 0.80]), and the smallest was for adults of Other ethnicity (62.04% vs. 59.68% [aOR: 0.88, 95% CI: 0.69, 1.14]).

Area-level deprivation

For all three screening programmes, participation was lowest among people living in the most deprived quintile of areas, both for the SMI and non-SMI populations (Bowel: 36.17% and 47.86%, respectively; Breast: 40.23% vs. 50.36%; Cervical: 61.47% vs. 64.59%). Similar to ethnicity, after adjusting for the impact of other factors, adults with SMI across all deprivation quintiles show significantly lower participation for all three cancer screening programmes. Participation in bowel cancer screening, by deprivation quintile, was consistently 15 percentage points lower among those with SMI, with the exception of the most deprived quintile, where the difference in participation, between those with and without SMI, was around 11 percentage points [47.86% vs. 36.17%; aOR: 0.64, 95% CI: 0.60, 0.67]. For cervical screening inequality increased with increasing deprivation, with the difference in participation, between women with and without SMI, being 5.00 percentage points in the least deprived quintile of areas, and 7.12 percentage points in the most deprived quintile of areas. As with cervical screening, differences in participation for breast cancer screening differences, between adults with and without SMI, widened gradually, as deprivation increased (from 8.08 percentage points [67.54 vs. 59.46%; aOR: 0.69, 95% CI: 0.64, 0.75] in the least deprived quintile, to around 10.61 percentage points [55.26 vs. 44.65%; aOR: 0.68, 95% CI: 0.63, 0.72] in the second most deprived quintile [and the difference narrowing again for the most deprived quintile of areas]).

Region

Participation for all three screening programmes was lowest in London, both for people with and without SMI (participation in bowel cancer screening, for people with and without SMI, living in London, was 37.66% and 52.33%, respectively; participation in breast cancer screening, for people with and without SMI, living in London, was 38.50% and 49.06%, respectively; participation in cervical screening, for people with and without SMI, living in London, was 62.51% and 65.29%, respectively).

Across all regions in England, adults with SMI, compared to adults without SMI, experience significantly lower participation in all three cancer screening programmes, after adjusting for the impact of other factors. The widest regional inequalities in cancer screening participation, between people with and without SMI, were observed in the South West for bowel cancer screening, and the North East for breast and cervical screening (participation in bowel cancer screening, by people with and without SMI, living in the South West, was 43.19% and 60.27%, respectively [aOR: 0.55, 95% CI: 0.50, 0.59]; participation in breast cancer screening, by people with and without SMI, living in the North East, was 53.02% and 65.59%, respectively [aOR: 0.60, 95% CI: 0.51, 0.71]; participation in cervical screening, by people with and without SMI, living in the North East, was 61.58% and 71.40%, respectively, [aOR: 0.66, 95% CI: 0.58, 0.75]).

Smoking status

Participation in bowel, breast and cervical screening was lower among smokers than non-smokers, both for adults with and without SMI (see Tables 2–4). Inequalities in bowel cancer screening participation, between people with and without SMI, did not appear to be exacerbated by smoking status (there was a 15.5 percentage points difference in participation in bowel cancer screening between non-smokers, with and without SMI [47.00% vs. 62.47%; aOR: 0.55, 95% CI: 0.53, 0.58], and a 14.7 percentage points difference in participation between smokers [37.63% vs. 52.33% [aOR: 0.59, 95% CI: 0.57, 0.61]). The same was true for breast cancer screening (there was a 10.3 percentage points difference in participation in breast cancer screening [51.91% vs. 62.22%; aOR: 0.71, 95% CI: 0.68, 0.74], and a 12.0 percentage point difference in participation between smokers [45.18% vs. 57.18% [aOR: 0.66, 95% CI: 0.63, 0.69]) and cervical screening (there was a 6.7 percentage point difference in participation in cervical screening between non-smokers, with and without SMI [63.22% vs. 69.91%; aOR: 0.73, 95% CI: 0.70, 0.75], and a 4.5 percentage point difference in participation between smokers [64.85% vs. 69.39% [aOR: 0.83, 95% CI: 0.80, 0.86]).

BMI

For people with SMI, participation in bowel cancer screening was slightly higher among those with a BMI > 30 (see Table 2). Conversely, for people without SMI, it was slightly lower for those with a BMI > 30. As a result, differences in bowel cancer screening participation, between people with and without SMI, reduced with increased BMI (there was a 17.2 percentage point difference in participation in bowel cancer screening between people with a BMI < 30, [41.83% vs. 59.04%; aOR: 0.56, 95% CI: 0.54, 0.58], and a 12.6 percentage point difference in participation between people with a BMI > 30 [44.26% vs. 56.90% [aOR: 0.67, 95% CI: 0.62, 0.73]). With regards to breast cancer screening, participation was the same for people with a BMI < 30, as people with a BMI > 30, irrespective of whether they had SMI (see Table 3).

For cervical screening, participation did not vary by BMI for those without SMI. For people with SMI, however, participation was slightly lower among people with a BMI < 30 compared to those with a BMI > 30 (see Table 4). As with bowel screening, therefore, inequalities in cervical screening participation, between people with and without SMI, were slightly reduced with increasing BMI (there was a 5.8 percentage point difference in participation in cervical cancer screening among those with a BMI < 30 [63.89% vs. 69.67%; aOR: 0.78, 95% CI: 0.76, 0.80], and a 4.7 percentage point difference in participation between people with a BMI > 30 [66.04% vs. 70.72% [aOR: 0.81, 95% CI: 0.75, 0.87]).