The role of vaccines in reducing antimicrobial resistance: A review of potential impact of vaccines on AMR and insights across 16 vaccines and pathogens.

In 2019, an estimated 4.95 million deaths were linked to antimicrobial resistance (AMR). Vaccines can prevent many of these deaths by averting both drug-sensitive and resistant infections, reducing antibiotic usage, and lowering the likelihood of developing resistance genes. However, their role in mitigating AMR is currently underutilized. This article builds upon previous research that utilizes Vaccine Value Profiles-tools that assess the health, socioeconomic, and societal impact of pathogens-to inform vaccine development. We analyze the effects of 16 pathogens, covered by Vaccine Value Profiles, on AMR, and explore how vaccines could reduce AMR. The article also provides insights into vaccine development and usage. Vaccines are crucial in lessening the impact of infectious diseases and curbing the development of AMR. To fully realize their potential, vaccines must be more prominently featured in the overall strategy to combat AMR. This requires ongoing investment in research and development of new vaccines and the implementation of additional prevention and control measures to address this global threat effectively.

Feasibility, safety, and impact of the RTS,S/AS01E malaria vaccine when implemented through national immunisation programmes: evaluation of cluster-randomised introduction of the vaccine in Ghana, Kenya, and Malawi.

BACKGROUND: The RTS,S/AS01E malaria vaccine (RTS,S) was introduced by national immunisation programmes in Ghana, Kenya, and Malawi in 2019 in large-scale pilot schemes. We aimed to address questions about feasibility and impact, and to assess safety signals that had been observed in the phase 3 trial that included an excess of meningitis and cerebral malaria cases in RTS,S recipients, and the possibility of an excess of deaths among girls who received RTS,S than in controls, to inform decisions about wider use. METHODS: In this prospective evaluation, 158 geographical clusters (66 districts in Ghana; 46 sub-counties in Kenya; and 46 groups of immunisation clinic catchment areas in Malawi) were randomly assigned to early or delayed introduction of RTS,S, with three doses to be administered between the ages of 5 months and 9 months and a fourth dose at the age of approximately 2 years. Primary outcomes of the evaluation, planned over 4 years, were mortality from all causes except injury (impact), hospital admission with severe malaria (impact), hospital admission with meningitis or cerebral malaria (safety), deaths in girls compared with boys (safety), and vaccination coverage (feasibility). Mortality was monitored in children aged 1-59 months throughout the pilot areas. Surveillance for meningitis and severe malaria was established in eight sentinel hospitals in Ghana, six in Kenya, and four in Malawi. Vaccine uptake was measured in surveys of children aged 12-23 months about 18 months after vaccine introduction. We estimated that sufficient data would have accrued after 24 months to evaluate each of the safety signals and the impact on severe malaria in a pooled analysis of the data from the three countries. We estimated incidence rate ratios (IRRs) by comparing the ratio of the number of events in children age-eligible to have received at least one dose of the vaccine (for safety outcomes), or age-eligible to have received three doses (for impact outcomes), to that in non-eligible age groups in implementation areas with the equivalent ratio in comparison areas. To establish whether there was evidence of a difference between girls and boys in the vaccine's impact on mortality, the female-to-male mortality ratio in age groups eligible to receive the vaccine (relative to the ratio in non-eligible children) was compared between implementation and comparison areas. Preliminary findings contributed to WHO's recommendation in 2021 for widespread use of RTS,S in areas of moderate-to-high malaria transmission. FINDINGS: By April 30, 2021, 652 673 children had received at least one dose of RTS,S and 494 745 children had received three doses. Coverage of the first dose was 76% in Ghana, 79% in Kenya, and 73% in Malawi, and coverage of the third dose was 66% in Ghana, 62% in Kenya, and 62% in Malawi. 26 285 children aged 1-59 months were admitted to sentinel hospitals and 13 198 deaths were reported through mortality surveillance. Among children eligible to have received at least one dose of RTS,S, there was no evidence of an excess of meningitis or cerebral malaria cases in implementation areas compared with comparison areas (hospital admission with meningitis: IRR 0·63 [95% CI 0·22-1·79]; hospital admission with cerebral malaria: IRR 1·03 [95% CI 0·61-1·74]). The impact of RTS,S introduction on mortality was similar for girls and boys (relative mortality ratio 1·03 [95% CI 0·88-1·21]). Among children eligible for three vaccine doses, RTS,S introduction was associated with a 32% reduction (95% CI 5-51%) in hospital admission with severe malaria, and a 9% reduction (95% CI 0-18%) in all-cause mortality (excluding injury). INTERPRETATION: In the first 2 years of implementation of RTS,S, the three primary doses were effectively deployed through national immunisation programmes. There was no evidence of the safety signals that had been observed in the phase 3 trial, and introduction of the vaccine was associated with substantial reductions in hospital admission with severe malaria. Evaluation continues to assess the impact of four doses of RTS,S. FUNDING: Gavi, the Vaccine Alliance; the Global Fund to Fight AIDS, Tuberculosis and Malaria; and Unitaid.

Post-Discharge Risk of Mortality in Children under 5 Years of Age in Western Kenya: A Retrospective Cohort Study.

Limited evidence suggests that children in sub-Saharan Africa hospitalized with all-cause severe anemia or severe acute malnutrition (SAM) are at high risk of dying in the first few months after discharge. We aimed to compare the risks of post-discharge mortality by health condition among hospitalized children in an area with high malaria transmission in western Kenya. We conducted a retrospective cohort study among recently discharged children aged < 5 years using mortality data from a health and demographic surveillance system that included household and pediatric in-hospital surveillance. Cox regression was used to compare post-discharge mortality. Between 2008 and 2013, overall in-hospital mortality was 2.8% (101/3,639). The mortality by 6 months after discharge (primary outcome) was 6.2% (159/2,556) and was highest in children with SAM (21.6%), followed by severe anemia (15.5%), severe pneumonia (5.6%), "other conditions" (5.6%), and severe malaria (0.7%). Overall, the 6-month post-discharge mortality in children hospitalized with SAM (hazard ratio [HR] = 3.95, 2.60-6.00, P < 0.001) or severe anemia (HR = 2.55, 1.74-3.71, P < 0.001) was significantly higher than that in children without these conditions. Severe malaria was associated with lower 6-month post-discharge mortality than children without severe malaria (HR = 0.33, 0.21-0.53, P < 0.001). The odds of dying by 6 months after discharge tended to be higher than during the in-hospital period for all children, except for those admitted with severe malaria. The first 6 months after discharge is a high-risk period for mortality among children admitted with severe anemia and SAM in western Kenya. Strategies to address this risk period are urgently needed.

A Survey of Demographics, Symptom Course, Family History, and Barriers to Treatment in Children with Pediatric Acute-Onset Neuropsychiatric Disorders and Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal Infections.

Objective: Few large-scale studies of pediatric acute-onset neuropsychiatric syndrome (PANS) and pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS) have been conducted, and thus demographic data on these conditions are limited. The current study describes comorbid medical and psychiatric conditions in a self-referred cohort of children with PANS/PANDAS, along with treatment history, barriers to treatment, family medical and psychiatric history, and perceived caregiver burden in these conditions. Methods: A total of 441 primary caregivers of patients with infection-triggered PANS/PANDAS under the age of 18 were included in this online anonymous survey, reporting on a total of 490 children (due to some caregivers reporting multiple children in the family with PANS/PANDAS). Data were collected between July 2018 and May 2019. Primary caregivers completed questions pertaining to patient demographics, symptom presentation, disease course, family medical and psychiatric history, and severity of patients' obsessive-compulsive disorder (OCD) symptoms. Results: OCD was the most common psychiatric symptom reported in children at the onset of PANS/PANDAS (83.06%), along with a high percentage of medical and psychiatric comorbidities. Most psychiatric comorbidities began or worsened at the onset of PANS/PANDAS symptoms, while major depressive disorder was the most frequently reported psychiatric disorder to develop after PANS/PANDAS onset (10%). A high frequency of autoimmune and inflammatory conditions was reported in family members, with nearly 30% of mothers endorsing one or more autoimmune conditions (29.95%). Mean caregiver burden (Caregiver Burden Inventory; M = 44.0) fell above the "burnout" level, and standardized measures showed mildly elevated levels of depression, anxiety, and stress in caregivers (Depression, Anxiety, and Stress Scale-21; M = 11.85, 7.16, and 15.56, respectively). Conclusions: Primary caregivers of children with PANS/PANDAS reported a multitude of medical and psychiatric comorbidities in their children, along with a high frequency of autoimmune and psychiatric conditions in family members. Obsessive-compulsive symptoms were the most frequently reported psychiatric symptom. Caregivers of these patients experience elevated levels of burden, stress, anxiety, and depression. Further research is needed to better understand the varied disease course in PANS/PANDAS and to develop interventions to reduce caregiver burden in these disorders.

Temporal trends in molecular markers of drug resistance in Plasmodium falciparum in human blood and profiles of corresponding resistant markers in mosquito oocysts in Asembo, western Kenya.

BACKGROUND: Over the last two decades, the scale-up of vector control and changes in the first-line anti-malarial, from chloroquine (CQ) to sulfadoxine-pyrimethamine (SP) and then to artemether-lumefantrine (AL), have resulted in significant decreases in malaria burden in western Kenya. This study evaluated the long-term effects of control interventions on molecular markers of Plasmodium falciparum drug resistance using parasites obtained from humans and mosquitoes at discrete time points. METHODS: Dried blood spot samples collected in 2012 and 2017 community surveys in Asembo, Kenya were genotyped by Sanger sequencing for markers associated with resistance to SP (Pfdhfr, Pfdhps), CQ, AQ, lumefantrine (Pfcrt, Pfmdr1) and artemisinin (Pfk13). Temporal trends in the prevalence of these markers, including data from 2012 to 2017 as well as published data from 1996, 2001, 2007 from same area, were analysed. The same markers from mosquito oocysts collected in 2012 were compared with results from human blood samples. RESULTS: The prevalence of SP dhfr/dhps quintuple mutant haplotype C50I51R59N108I164/S436G437E540A581A613 increased from 19.7% in 1996 to 86.0% in 2012, while an increase in the sextuple mutant haplotype C50I51R59N108I164/H436G437E540A581A613 containing Pfdhps-436H was found from 10.5% in 2012 to 34.6% in 2017. Resistant Pfcrt-76 T declined from 94.6% in 2007 to 18.3% in 2012 and 0.9% in 2017. Mutant Pfmdr1-86Y decreased across years from 74.8% in 1996 to zero in 2017, mutant Pfmdr1-184F and wild Pfmdr1-D1246 increased from 17.9% to 58.9% in 2007 to 55.9% and 90.1% in 2017, respectively. Pfmdr1 haplotype N86F184S1034N1042D1246 increased from 11.0% in 2007 to 49.6% in 2017. No resistant mutations in Pfk13 were found. Prevalence of Pfdhps-436H was lower while prevalence of Pfcrt-76 T was higher in mosquitoes than in human blood samples. CONCLUSION: This study showed an increased prevalence of dhfr/dhps resistant markers over 20 years with the emergence of Pfdhps-436H mutant a decade ago in Asembo. The reversal of Pfcrt from CQ-resistant to CQ-sensitive genotype occurred following 19 years of CQ withdrawal. No Pfk13 markers associated with artemisinin resistance were detected, but the increased haplotype of Pfmdr1 N86F184S1034N1042D1246 was observed. The differences in prevalence of Pfdhps-436H and Pfcrt-76 T SNPs between two hosts and the role of mosquitoes in the transmission of drug resistant parasites require further investigation.

Strategies for discussing long-term prognosis when deciding on cancer screening for adults over age 75.

BACKGROUND: Consideration of older adults' 10-year prognosis is necessary for high-quality cancer screening decisions. However, few primary care providers (PCPs) discuss long-term (10-year) prognosis with older adults. METHODS: To learn PCPs' and older adults' perspectives on and to develop strategies for discussing long-term prognosis in the context of cancer screening decisions, we conducted qualitative individual interviews with adults 76-89 and focus groups or individual interviews with PCPs. We recruited participants from 4 community and 2 academic Boston-area practices and completed a thematic analysis of participant responses to open-ended questions on discussing long-term prognosis. RESULTS: Forty-five PCPs (21 community-based) participated in 7 focus groups or 7 individual interviews. Thirty patients participated; 19 (63%) were female, 13 (43%) were non-Hispanic Black, and 13 (43%) were non-Hispanic white. Patients and PCPs had varying views on the utility of discussing long-term prognosis. "For some patients and for some families having this information is really helpful," (PCP participant). Some participants felt that prognostic information could be helpful for future planning, whereas others thought the information could be anxiety-provoking or of "no value" because death is unpredictable; still others were unsure about the value of these discussions. Patients often described thinking about their own prognosis. Yet, PCPs described feeling uncomfortable with these conversations. Patients recommended that discussion of long-term prognosis be anchored to clinical decisions, that information be provided on how this information may be useful, and that patient interest in prognosis be assessed before prognostic information is offered. PCPs recommended that scripts be brief. These recommendations were used to develop example scripts to guide these conversations. CONCLUSIONS: We developed scripts and strategies for PCPs to introduce the topic of long-term prognosis with older adults and to provide numerical prognostic information to those interested. Future studies will need to test the effect of these strategies in practice.

Primary Care Providers' Perceptions of the Acceptability, Appropriateness, and Feasibility of a Mammography Decision Aid for Women Aged 75 and Older.

Background. Clinicians need to find decision aids (DAs) useful for their successful implementation. Therefore, we aimed to conduct an exploratory study to learn primary care clinicians' (PCPs) perspectives on a mammography DA for women ≥75 to inform its implementation. Methods. We sent a cross-sectional survey to 135 PCPs whose patients had participated in a randomized trial of the DA. These PCPs practiced at 1 of 11 practices in Massachusetts or North Carolina. PCPs were asked closed-ended and open-ended questions on shared decision making (SDM) around mammography with women ≥75 and on the DA's acceptability, appropriateness, and feasibility. Results. Eighty PCPs participated (24 [30%] from North Carolina). Most (n = 69, 86%) thought that SDM about mammography with women ≥75 was extremely/very important and that they engaged women ≥75 in SDM around mammography frequently/always (n = 49, 61%). Regarding DA acceptability, 60% felt the DA was too long. Regarding appropriateness, 70 (89%) thought it was somewhat/very helpful and that it would help patients make more informed decisions; 55 (70%) would recommend it. Few (n = 6, 8%) felt they had other resources to support this decision. Regarding feasibility, 53 (n = 67%) thought it would be most feasible for patients to receive the DA before a visit from medical assistants rather than during or after a visit or from health educators. Most (n = 62, 78%) wanted some training to use the DA. Limitations. Sixty-nine percent of PCPs in this small study practiced in academic settings. Conclusions. Although PCPs were concerned about the DA's length, most found it helpful and informative and felt it would be feasible for medical assistants to deliver the DA before a visit. Implications. Study findings may inform implementation of this and other DAs.

Development of a new barcode-based, multiplex-PCR, next-generation-sequencing assay and data processing and analytical pipeline for multiplicity of infection detection of Plasmodium falciparum.

BACKGROUND: Simultaneous infection with multiple malaria parasite strains is common in high transmission areas. Quantifying the number of strains per host, or the multiplicity of infection (MOI), provides additional parasite indices for assessing transmission levels but it is challenging to measure accurately with current tools. This paper presents new laboratory and analytical methods for estimating the MOI of Plasmodium falciparum. METHODS: Based on 24 single nucleotide polymorphisms (SNPs) previously identified as stable, unlinked targets across 12 of the 14 chromosomes within P. falciparum genome, three multiplex PCRs of short target regions and subsequent next generation sequencing (NGS) of the amplicons were developed. A bioinformatics pipeline including B4Screening pathway removed spurious amplicons to ensure consistent frequency calls at each SNP location, compiled amplicons by SNP site diversity, and performed algorithmic haplotype and strain reconstruction. The pipeline was validated by 108 samples generated from cultured-laboratory strain mixtures in different proportions and concentrations, with and without pre-amplification, and using whole blood and dried blood spots (DBS). The pipeline was applied to 273 smear-positive samples from surveys conducted in western Kenya, then providing results into StrainRecon Thresholding for Infection Multiplicity (STIM), a novel MOI estimator. RESULTS: The 24 barcode SNPs were successfully identified uniformly across the 12 chromosomes of P. falciparum in a sample using the pipeline. Pre-amplification and parasite concentration, while non-linearly associated with SNP read depth, did not influence the SNP frequency calls. Based on consistent SNP frequency calls at targeted locations, the algorithmic strain reconstruction for each laboratory-mixed sample had 98.5% accuracy in dominant strains. STIM detected up to 5 strains in field samples from western Kenya and showed declining MOI over time (q < 0.02), from 4.32 strains per infected person in 1996 to 4.01, 3.56 and 3.35 in 2001, 2007 and 2012, and a reduction in the proportion of samples with 5 strains from 57% in 1996 to 18% in 2012. CONCLUSION: The combined approach of new multiplex PCRs and NGS, the unique bioinformatics pipeline and STIM could identify 24 barcode SNPs of P. falciparum correctly and consistently. The methodology could be applied to field samples to reliably measure temporal changes in MOI.

Impact of Community-Based Mass Testing and Treatment on Malaria Infection Prevalence in a High-Transmission Area of Western Kenya: A Cluster Randomized Controlled Trial.

BACKGROUND: Global gains toward malaria elimination have been heterogeneous and have recently stalled. Interventions targeting afebrile malaria infections may be needed to address residual transmission. We studied the efficacy of repeated rounds of community-based mass testing and treatment (MTaT) on malaria infection prevalence in western Kenya. METHODS: Twenty clusters were randomly assigned to 3 rounds of MTaT per year for 2 years or control (standard of care for testing and treatment at public health facilities along with government-sponsored mass long-lasting insecticidal net [LLIN] distributions). During rounds, community health volunteers visited all households in intervention clusters and tested all consenting individuals with a rapid diagnostic test. Those positive were treated with dihydroartemisinin-piperaquine. Cross-sectional community infection prevalence surveys were performed in both study arms at baseline and each year after 3 rounds of MTaT. The primary outcome was the effect size of MTaT on parasite prevalence by microscopy between arms by year, adjusted for age, reported LLIN use, enhanced vegetative index, and socioeconomic status. RESULTS: Demographic and behavioral characteristics, including LLIN usage, were similar between arms at each survey. MTaT coverage across the 3 annual rounds ranged between 75.0% and 77.5% in year 1, and between 81.9% and 94.3% in year 2. The adjusted effect size of MTaT on the prevalence of parasitemia between arms was 0.93 (95% confidence interval [CI], .79-1.08) and 0.92 (95% CI, .76-1.10) after year 1 and year 2, respectively. CONCLUSIONS: MTaT performed 3 times per year over 2 years did not reduce malaria parasite prevalence in this high-transmission area. CLINICAL TRIALS REGISTRATION: NCT02987270.

A Strategy to Prepare Primary Care Clinicians for Discussing Stopping Cancer Screening With Adults Older Than 75 Years.

BACKGROUND AND OBJECTIVES: Adults older than 75 years are overscreened for cancer, especially those with less than 10-year life expectancy. This study aimed to learn the effects of providing primary care providers (PCPs) with scripts for discussing stopping mammography and colorectal cancer (CRC) screening and with information on patient's 10-year life expectancy on their patients' intentions to be screened for these cancers. RESEARCH DESIGN AND METHODS: Patient participants, identified via PCP appointment logs, completed a questionnaire pre- and postvisit. Primary care providers were given scripts for discussing stopping screening and information on patient's 10-year life expectancy before these visits. Primary care providers completed a questionnaire at the end of the study. Patients and PCPs were asked about discussing stopping cancer screening and patient life expectancy. Patient screening intentions (1-15 Likert scale; lower scores suggest lower intentions) were compared pre- and postvisit using the Wilcoxon signed-rank test. RESULTS: Ninety patients older than 75 years (47% of eligible patients reached by phone) from 45 PCPs participated. Patient mean age was 80.0 years (SD = 2.9), 43 (48%) were female, and mean life expectancy was 9.7 years (SD = 2.4). Thirty-seven PCPs (12 community-based) completed a questionnaire. Primary care providers found the scripts helpful (32 [89%]) and thought they would use them frequently (29 [81%]). Primary care providers also found patient life expectancy information helpful (35 [97%]). However, only 8 PCPs (22%) reported feeling comfortable discussing patient life expectancy. Patients' intentions to undergo CRC screening (9.0 [SD = 5.3] to 6.5 [SD = 6.0], p < .0001) and mammography screening (12.9 [SD = 3.0] to 11.7 [SD = 4.9], p = .08) decreased from pre- to postvisit (significantly for CRC). Sixty-three percent of patients (54/86) were interested in discussing life expectancy with their PCP previsit and 56% (47/84) postvisit. DISCUSSION AND IMPLICATIONS: PCPs found scripts for discussing stopping cancer screening and information on patient life expectancy helpful. Possibly, as a result, their patients older than 75 years had lower intentions of being screened for CRC. CLINICAL TRIALS REGISTRATION NUMBER: NCT03480282.

Impact of Intermittent Mass Testing and Treatment on Incidence of Malaria Infection in a High Transmission Area of Western Kenya.

Progress with malaria control in western Kenya has stagnated since 2007. Additional interventions to reduce the high burden of malaria in this region are urgently needed. We conducted a two-arm, community-based, cluster-randomized, controlled trial of active case detection and treatment of malaria infections in all residents mass testing and treatment (MTaT) of 10 village clusters (intervention clusters) for two consecutive years to measure differences in the incidence of clinical malaria disease and malaria infections compared with 20 control clusters where MTaT was not implemented. All residents of intervention clusters, irrespective of history of fever or other malaria-related symptoms, were tested three times per year before the peak malaria season using malaria rapid diagnostic tests. All positive cases were treated with dihydroartemisinin-piperaquine. The incidence of clinical malaria was measured through passive surveillance, whereas the cumulative incidence of malaria infection was measured using active surveillance in a cohort comprising randomly selected residents. The incidence of clinical malaria was 0.19 cases/person-year (p-y, 95% CI: 0.13-0.28) in the intervention arm and 0.24 cases/p-y (95% CI: 0.15-0.39) in the control arm (incidence rate ratio [IRR] 0.79, 95% CI: 0.61-1.02). The cumulative incidence of malaria infections was similar between the intervention (2.08 infections/p-y, 95% CI: 1.93-2.26) and control arms (2.19 infections/p-y, 95% CI: 2.02-2.37) with a crude IRR of 0.95 (95% CI: 0.87-1.04). Six rounds of MTaT over 2 years did not have a significant impact on the incidence of clinical malaria or the cumulative incidence of malaria infection in this area of high malaria transmission.

Effect of a Mammography Screening Decision Aid for Women 75 Years and Older: A Cluster Randomized Clinical Trial.

Importance: Guidelines recommend that women 75 years and older be informed of the benefits and harms of mammography before screening. Objective: To test the effects of receipt of a paper-based mammography screening decision aid (DA) for women 75 years and older on their screening decisions. Design, Setting, and Participants: A cluster randomized clinical trial with clinician as the unit of randomization. All analyses were completed on an intent-to-treat basis. The setting was 11 primary care practices in Massachusetts or North Carolina. Of 1247 eligible women reached, 546 aged 75 to 89 years without breast cancer or dementia who had a mammogram within 24 months but not within 6 months and saw 1 of 137 clinicians (herein referred to as PCPs) from November 3, 2014, to January 26, 2017, participated. A research assistant (RA) administered a previsit questionnaire on each participant's health, breast cancer risk factors, sociodemographic characteristics, and screening intentions. After the visit, the RA administered a postvisit questionnaire on screening intentions and knowledge. Interventions: Receipt of the DA (DA arm) or a home safety (HS) pamphlet (control arm) before a PCP visit. Main Outcomes and Measures: Participants were followed up for 18 months for receipt of mammography screening (primary outcome). To examine the effects of the DA, marginal logistic regression models were fit using generalized estimating equations to allow for clustering by PCP. Adjusted probabilities and risk differences were estimated to account for clustering by PCP. Results: Of 546 women in the study, 283 (51.8%) received the DA. Patients in each arm were well matched; their mean (SD) age was 79.8 (3.7) years, 428 (78.4%) were non-Hispanic white, 321 (of 543 [59.1%]) had completed college, and 192 (35.2%) had less than a 10-year life expectancy. After 18 months, 9.1% (95% CI, 1.2%-16.9%) fewer women in the DA arm than in the control arm had undergone mammography screening (51.3% vs 60.4%; adjusted risk ratio, 0.84; 95% CI, 0.75-0.95; P = .006). Women in the DA arm were more likely than those in the control arm to rate their screening intentions lower from previsit to postvisit (69 of 283 [adjusted %, 24.5%] vs 47 of 263 [adjusted %, 15.3%]), to be more knowledgeable about the benefits and harms of screening (86 [adjusted %, 25.5%] vs 32 [adjusted %, 11.7%]), and to have a documented discussion about mammography with their PCP (146 [adjusted %, 47.4%] vs 111 [adjusted %, 38.9%]). Almost all women in the DA arm (94.9%) would recommend the DA. Conclusions and Relevance: Providing women 75 years and older with a mammography screening DA before a PCP visit helps them make more informed screening decisions and leads to fewer women choosing to be screened, suggesting that the DA may help reduce overscreening. Trial Registration: ClinicalTrials.gov Identifier: NCT02198690.