Comparing screening based on the NHS Health Check and Polypill Prevention Programmes in the primary prevention of heart attacks and strokes.

OBJECTIVE: To compare the NHS Health Check Programme with the Polypill Prevention Programme in the primary prevention of heart attacks and strokes. DESIGN: Use of published data and methodology to produce flow charts of the two programmes to determine screening performance and heart attacks and strokes prevented. SETTING: The UK population. INTERVENTION: The NHS Health Check Programme using a QRISK score on people aged 40-74 to select those eligible for a statin is compared with the Polypill Prevention Programme in people aged 50 or more to select people for a combination of a statin and three low-dose blood pressure lowering agents. In both programmes, people had no history of heart attack or stroke. MAIN OUTCOME MEASURES: In 1000 people, the number of heart attacks and strokes prevented in the two programmes. RESULTS: In the hypothetical perfect situation with 100% uptake and adherence to the screening protocol, in every 1000 persons, the NHS Health Check would prevent 287 cases of a heart attack or stroke in individuals who would gain on average about 4 years of life without a heart attack or stroke amounting to 1148 years in total, the precise gain depending on the extent of treatment for those with raised blood pressure, and 136 would be prescribed statins with no benefit. The corresponding figures for the Polypill Prevention Programme are 316 individuals who would, on average, gain 8 years of life without a heart attack or stroke, amounting to 2528 years in total, and 260 prescribed the polypill with no benefit. Based on published estimates of uptake and adherence in the NHS Health Check Programme, in practice only 24 cases per 1000 are currently benefitting instead of 287, amounting to 96 years gained without a heart attack or stroke. CONCLUSIONS: The Polypill Prevention Programme is by design simpler with the potential of preventing many more heart attacks and strokes than the NHS Health Check Programme.

The polypill in the primary prevention of heart attacks and strokes: Overcoming barriers to implementation.

This commentary, linked to our paper in the same issue of the Journal of Medical Screening, discusses the reluctance to consider and adopt the polypill in the primary prevention of heart attacks and strokes, access to the polypill as a public health service, the formulation of the polypill in current use, its prescription as an unlicensed medicine, and what can be done to facilitate the adoption of the polypill approach as a routine public health service.

Performance of polygenic risk scores in screening, prediction, and risk stratification: secondary analysis of data in the Polygenic Score Catalog.

Objective: To clarify the performance of polygenic risk scores in population screening, individual risk prediction, and population risk stratification. Design: Secondary analysis of data in the Polygenic Score Catalog. Setting: Polygenic Score Catalog, April 2022. Secondary analysis of 3915 performance metric estimates for 926 polygenic risk scores for 310 diseases to generate estimates of performance in population screening, individual risk, and population risk stratification. Participants: Individuals contributing to the published studies in the Polygenic Score Catalog. Main outcome measures: Detection rate for a 5% false positive rate (DR5) and the population odds of becoming affected given a positive result; individual odds of becoming affected for a person with a particular polygenic score; and odds of becoming affected for groups of individuals in different portions of a polygenic risk score distribution. Coronary artery disease and breast cancer were used as illustrative examples. Results: For performance in population screening, median DR5 for all polygenic risk scores and all diseases studied was 11% (interquartile range 8-18%). Median DR5 was 12% (9-19%) for polygenic risk scores for coronary artery disease and 10% (9-12%) for breast cancer. The population odds of becoming affected given a positive results were 1:8 for coronary artery disease and 1:21 for breast cancer, with background 10 year odds of 1:19 and 1:41, respectively, which are typical for these diseases at age 50. For individual risk prediction, the corresponding 10 year odds of becoming affected for individuals aged 50 with a polygenic risk score at the 2.5th, 25th, 75th, and 97.5th centiles were 1:54, 1:29, 1:15, and 1:8 for coronary artery disease and 1:91, 1:56, 1:34, and 1:21 for breast cancer. In terms of population risk stratification, at age 50, the risk of coronary artery disease was divided into five groups, with 10 year odds of 1:41 and 1:11 for the lowest and highest quintile groups, respectively. The 10 year odds was 1:7 for the upper 2.5% of the polygenic risk score distribution for coronary artery disease, a group that contributed 7% of cases. The corresponding estimates for breast cancer were 1:72 and 1:26 for the lowest and highest quintile groups, and 1:19 for the upper 2.5% of the distribution, which contributed 6% of cases. Conclusion: Polygenic risk scores performed poorly in population screening, individual risk prediction, and population risk stratification. Strong claims about the effect of polygenic risk scores on healthcare seem to be disproportionate to their performance.

Validation of a monoclonal unconjugated estriol antibody for use in prenatal maternal serum screening.

OBJECTIVES: Unconjugated estriol (uE3) is used as a marker for fetal aneuploidy in maternal serum screening tests. The goal of this study was to examine the validity of a new immunoassay for uE3 that uses a monoclonal antibody (m-uE3) rather than the more commonly used polyclonal antibody (p-uE3). SETTING: Assays were performed in the Special Chemistry laboratory at Women and Infants Hospital of Rhode Island. METHODS: Residual fresh (n = 100) and frozen (n = 533) second trimester serum samples from routine clinical care were tested using p-uE3 and/or m-uE3 assays. Assay results were compared between methods using Bland-Altman plots. A median equation was developed for m-uE3 results. Down syndrome risks were compared between the two assays in a case-control sample set (21 cases each matched with five controls for the completed week of gestation, duration of freezer storage and race). RESULTS: Log-transformed serum uE3 levels were highly correlated between the assays (r = 0.93, p < 0.001), with the m-uE3 assay levels yielding, on average, 23% higher (standard deviation of differences in log uE3 concentrations = 0.07) results. Assay and gestation-based median equations were calculated and used to convert m-uE3 concentrations to multiples of the median (MoM). The m-uE3 MoM values fit a log Gaussian distribution well with a log standard deviation of 0.11. Down syndrome risk results were not significantly different between assays. CONCLUSIONS: The m-uE3 assay, with results expressed in MoMs, is suitable for screening and as a monoclonal-based assay offers the advantage of a predictable and indefinite supply of antibody to perform the assay.

Folic acid and neural tube defects: Discovery, debate and the need for policy change.

Neural tube defects (NTDs) are a group of relatively common fatal or severely disabling birth defects that result in about 300,000 cases a year world-wide. The search for a cause was elusive, but in 1991 it was shown that about 8 out of 10 cases are due to a lack of vitamin B9 (folate) and are therefore preventable. This article (i) describes the challenge in finding the cause; (ii) examines the reasons for the failure of many countries to introduce folic acid fortification of staple foods such as flour and rice; (iii) shows that countries that have introduced fortification failed to do so in a fully effective way; (iv) shows how current preventive polices are confusing, inconsistent and sub-optimal; (v) shows that the proposed UK folic acid fortification policy is expected to prevent about 1 out of 10 NTD cases only; and (vi) proposes a simple, fully effective fortification policy that would prevent about 8 out of 10 NTDs and avoid the need for women to start taking folic acid supplements before pregnancy, a policy that has been shown to fail because only a small percentage of women adopt this practice.

Multi-marker risk-based screening for prostate cancer.

OBJECTIVE: To determine prostate cancer screening performance using prostate specific antigen (PSA) along with other markers, expressing markers in age-specific multiples of the median (MoM), and age. METHODS: A prospective nested case-control study used stored serum from 571 men who died of, or with history of, prostate cancer (cases), and 2169 matched controls. Total, free and intact PSA, human kallikrein-related peptidase 2 (hK2), and microseminoprotein were measured and converted into MoM values. Screening marker distribution parameters were estimated in cases and controls. Monte Carlo simulation used these in a risk-based algorithm to estimate screening performance (detection rates [DRs] and false-positive rates [FPRs]). RESULTS: Almost all (99%) cases occurred aged ≥55. Marker values were similar in cases who did and did not die of prostate cancer. Combining age, total PSA and hK2 MoM values (other markers added little or no discrimination) yielded a 1.2% FPR (95% CI 0.2-4.8%) for a 90% DR (59-98%) in men who died of or with a prostate cancer diagnosis within 5 years of blood collection (risk cut-off 1 in 20), two-thirds less than the 4.5% FPR using total PSA alone measured in ng/ml for the same 90% DR (cut-off 3.1 ng/ml). Screening performance over 10 years yielded a 33% (22-46%) FPR for a 90% DR. CONCLUSION: Screening performed up to every 5 years from age 55 using the multi-marker risk-based screening algorithm for future prostate cancer achieves a high DR and a much lower FPR than using PSA alone, resulting in reductions in overdiagnosis and overtreatment.

Lung cancer mortality reduction by LDCT screening: UKLS randomised trial results and international meta-analysis.

BACKGROUND: The NLST reported a significant 20% reduction in lung cancer mortality with three annual low-dose CT (LDCT) screens and the Dutch-Belgian NELSON trial indicates a similar reduction. We present the results of the UKLS trial. METHODS: From October 2011 to February 2013, we randomly allocated 4 055 participants to either a single invitation to screening with LDCT or to no screening (usual care). Eligible participants (aged 50-75) had a risk score (LLPv2) ≥ 4.5% of developing lung cancer over five years. Data were collected on lung cancer cases to 31 December 2019 and deaths to 29 February 2020 through linkage to national registries. The primary outcome was mortality due to lung cancer. We included our results in a random-effects meta-analysis to provide a synthesis of the latest randomised trial evidence. FINDINGS: 1 987 participants in the intervention and 1 981 in the usual care arms were followed for a median of 7.3 years (IQR 7.1-7.6), 86 cancers were diagnosed in the LDCT arm and 75 in the control arm. 30 lung cancer deaths were reported in the screening arm, 46 in the control arm, (relative rate 0.65 [95% CI 0.41-1.02]; p=0.062). The meta-analysis indicated a significant reduction in lung cancer mortality with a pooled overall relative rate of 0.84 (95% CI 0.76-0.92) from nine eligible trials. INTERPRETATION: The UKLS trial of single LDCT indicates a reduction of lung cancer death of similar magnitude to the NELSON and NLST trials and was included in a meta-analysis of nine randomised trials which provides unequivocal support for lung cancer screening in identified risk groups. FUNDING: NIHR Health Technology Assessment programme; NIHR Policy Research programme; Roy Castle Lung Cancer Foundation.

Integration of child-parent screening and cascade testing for familial hypercholesterolaemia.

OBJECTIVE: To integrate child-parent screening and cascade testing into a single pathway-child-parent cascade screening (CPCS), for the identification of familial hypercholesterolaemia in the population and to estimate the number of new familial hypercholesterolaemia cases identified per child screened and the associated costs. METHODS: We applied the results from the published MRC Child-Parent Screening Study to 10,000 children, together with cascade testing first degree relatives of parents with a familial hypercholesterolaemia mutation identified by child-parent screening. We estimated the number of familial hypercholesterolaemia cases identified per child screened, the median cost per familial hypercholesterolaemia case identified and the median cost per child screened to identify one case using a range of cholesterol and familial hypercholesterolaemia mutation testing costs. We present a case study to illustrate the application of CPCS in practice. RESULTS: CPCS identifies one new familial hypercholesterolaemia case per 70 children screened at a median estimated cost of £960 per new familial hypercholesterolaemia case or £4 per child screened. CPCS identifies an average of four new familial hypercholesterolaemia cases per family. In the case study, six new familial hypercholesterolaemia cases were identified, and preventive treatment started in five, with the index child expected to start when older. CONCLUSION: CPCS for familial hypercholesterolaemia are complementary strategies. The sustainability of cascade testing relies on identifying new unrelated index cases. This is achieved with population-wide child-parent screening. Integrated CPCS is currently better than either method of familial hypercholesterolaemia detection alone. It has the potential to identify all, or nearly all, individuals with familial hypercholesterolaemia in the population at low cost.

Prenatal screening for Down syndrome in twin pregnancies: Estimates of screening performance based on 61 affected and 7302 unaffected twin pregnancies.

The aims of this study were to determine whether assumptions used in prenatal screening for Down syndrome in twin pregnancies are valid and derive estimates of risk and screening performance in twin pregnancies using observed data. Data were collected on nuchal translucency, chorionicity, pregnancy associated plasma protein-A (PAPP-A), and free ß human chorionic gonadotrophin (free ß-hCG) from 61 twin pregnancies with Down syndrome and 7302 unaffected twin pregnancies. Distribution parameters were determined and used to estimate screening performance. The assumption that proportional differences in serum marker levels in affected and unaffected singleton pregnancies apply to twin pregnancies was not confirmed. Median free ß-hCG value in monochorionic affected twin pregnancies (2.63 multiples of the median [MoM]; 95% CI, 1.79-3.22 MoM) was lower than that assuming proportionality (3.76 MoM), and the median PAPP-A value in dichorionic affected twin pregnancies (1.88 MoM; 95% CI, 1.60-2.17 MoM) was higher than that based on proportionality (1.33 MoM). The detection rate was 87% for a 3% false-positive rate in monochorionic twin pregnancies and 74% in dichorionic twin pregnancies compared with 86% in singleton pregnancies. Estimates of screening performance in Down syndrome twin pregnancies do not need to rely on assumptions and can take account of chorionicity and gestational age.

Serum marker truncation limits in first trimester antenatal screening for trisomy 18.

OBJECTIVE: To assess whether the accuracy of risk estimation in antenatal screening for trisomy 18 using the Combined test can be improved by revising the truncation limits of two serum markers. METHODS: In an audit of data from 420 trisomy 18 and 573,754 unaffected singleton pregnancies screened at the Wolfson Institute of Preventive Medicine, London (March 2003 to June 2017), the accuracy of risk estimation was assessed by inspection of a validation plot (the median predicted late first trimester Combined test risk plotted against observed prevalence within categories of predicted risk estimates). Using validation and probability plots, we assessed whether the revised pregnancy-associated plasma protein A (PAPP-A) and free ß-human chorionic gonadotrophin (free ß-hCG) truncation limits led to more accurate risk estimation and improved screening performance. RESULTS: With the lower truncation limits currently used for PAPP-A and free ß-hCG (0.15 and 0.30 multiples of the median [MoM], respectively), risk was underestimated. Revised lower truncation limits of 0.05 MoM for both PAPP-A and free ß-hCG led to greater accuracy, with an increase in the number of trisomy 18 pregnancies detected (from 85.4% to 90.2%) for a small increase in the false-positive rate (from 0.20% to 0.29%) at a 1 in 100 late first trimester risk cut-off. CONCLUSION: The revised truncation limits for PAPP-A and free ß-hCG increase the accuracy of trisomy 18 risk estimation and improve screening performance using the Combined test. Validation and probability plots are useful in setting screening marker truncation limits.

Prenatal reflex DNA screening for trisomies 21, 18, and 13.

PURPOSE: The purpose of the study was to determine the screening performance of prenatal reflex DNA screening for trisomies 21 (T21), 18 (T18), and 13 (T13) as part of a routine service at five hospitals. METHODS: Women who accepted screening had a first-trimester combined test (pregnancy-associated plasma protein A, free ß-human chorionic gonadotropin, nuchal translucency interpreted with maternal age). Those with a risk of having an affected pregnancy ≥1 in 800 were reflexed to a DNA sequencing test using stored plasma from the original blood sample, thereby avoiding the need to recall them. RESULTS: Of 22,812 women screened (including 106 with affected pregnancies), 2,480 (10.9%) were reflexed to DNA testing; 101/106 were detected (69/73 T21, 24/25 T18, and 8/8 T13), a 95% detection rate (95% confidence interval 89-98%) with four false positives (0.02%, 95% confidence interval 0.00-0.05%). The odds of being affected given a positive result were 25:1. Of the 105 screen-positive pregnancies, 91 (87%) had an invasive diagnostic test. Reflex DNA screening avoided up to 530 invasive diagnostic tests compared with using the combined test. CONCLUSION: Reflex DNA screening was successfully implemented in routine care, achieving a high detection rate, low false-positive rate, and, consequently, greater safety with fewer invasive diagnostic tests than other methods of screening.

Prenatal maternal plasma DNA screening for cystic fibrosis: A computer modelling study of screening performance.

Background: Prenatal cystic fibrosis (CF) screening is currently based on determining the carrier status of both parents. We propose a new method based only on the analysis of DNA in maternal plasma. Methods: The method relies on the quantitative amplification of the CF gene to determine the percentage of DNA fragments in maternal plasma at targeted CF mutation sites that carry a CF mutation. Computer modelling was carried out to estimate the distributions of these percentages in pregnancies with and without a fetus affected with CF. This was done according to the number of DNA fragments counted and fetal fraction, using the 23 CF mutations recommended by the American College of Medical Genetics for parental carrier testing. Results: The estimated detection rate (sensitivity) is 70% (100% of those detected using the 23 mutations), the false-positive rate 0.002%, and the odds of being affected given a positive screening result 14:1, compared with 70%, 0.12%, and 1:3, respectively, with current prenatal screening based on parental carrier testing. Conclusions: Compared with current screening practice based on parental carrier testing, the proposed method would substantially reduce the number of invasive diagnostic procedures (amniocentesis or chorionic villus sampling) without reducing the CF detection rate. The expected advantages of the proposed method justify carrying out the necessary test development for use in a clinical validation study.