Real-world treatment patterns and clinical outcomes after introduction of immune checkpoint inhibitors: Results from a retrospective chart review of patients with advanced/metastatic non-small cell lung cancer in the EU5

BACKGROUND

Real-world evidence is increasingly used to guide treatment and regulatory decisions for non-small cell lung cancer (NSCLC). Real-world treatment patterns and clinical outcomes among patients with advanced/metastatic NSCLC in France, Germany, Italy, Spain, and the UK (EU5) were assessed.

METHODS

This retrospective physician-completed patient chart review assessed treatment patterns (regimen, duration of treatment [DOT], time to discontinuation), and clinical outcomes (duration of response [DOR], progression-free survival [PFS], and overall survival [OS]) of patients with stage IIIB/C or IV NSCLC who received pembrolizumab-based first-line induction chemotherapy.

RESULTS

Overall, 322 patients were included; at first-line maintenance (1LM), 92% had stage IV NSCLC, 68% had nonsquamous histology, and 89% had no central nervous system (CNS)/brain metastasis. The two most common 1LM regimens were pembrolizumab monotherapy (76% overall) and pembrolizumab + pemetrexed (21% overall). Docetaxel monotherapy was the most common second-line regimen in all countries except Germany (54% overall). For 1LM therapy, the overall median DOT and DOR were 5 and 10 months, respectively; PFS was 7 months and OS was 8 months. Germany had a longer duration of each outcome except for DOR which was longer in Spain. Clinical outcomes were generally poorer for patients with squamous histology and CNS/brain metastases.

CONCLUSIONS

This study demonstrated differences in treatment patterns and clinical outcomes in NSCLC across the EU5 and patient subgroups. Improved survival was generally associated with response to first-line therapy, nonsquamous histology, and CNS/brain metastases absence. These real-world data provide valuable insights which may aid treatment decision-making and clinical trial design.

Metastatic non-small-cell lung cancer without driver mutations: projections by therapy line in Western Europe, 2021-2026

Aim: To estimate the incidence, prevalence and treated prevalence by line of therapy (LOT) for non-small-cell lung cancer (NSCLC) patients without driver mutations from 2021 to 2026. Materials & methods: Country-specific registry data for Western Europe were used to project incidence and prevalence of NSCLC; LOT information was obtained from CancerMPact® Treatment Architecture physician surveys. Results: Incidence, prevalence and treated prevalence across LOTs for NSCLC are projected to increase across five WE countries, including for stage IV patients without driver mutations (184,966 cases [2021] to 197,925 [2026]). Pembrolizumab monotherapy is utilized by ∼50% of NSCLC patients with programmed death-ligand 1 expression ≥50%. Conclusion: Improved treatment options for NSCLC patients without known driver mutations are important for combating the projected increase in prevalence.

The Utility of ctDNA in Lung Cancer Clinical Research and Practice: A Systematic Review and Meta-analysis of Clinical Studies

This systematic review with embedded meta-analysis aimed to evaluate the clinical utility of circulating tumor DNA (ctDNA) in lung cancer. After screening and review of the Embase database search, 111 studies from 2015 to 2020 demonstrated ctDNA's value in prognostication/monitoring disease progression, mainly in patients with advanced/metastatic disease and non-small cell lung cancer. ctDNA positivity/detection at any time point was associated with shorter progression-free survival and overall survival, whereas ctDNA clearance/decrease during treatment was associated with lower risk of progression and death. Validating these findings and addressing challenges regarding ctDNA testing integration into clinical practice will require further research.

Abstract 6695: Utility of circulating tumor DNA in breast cancer clinical research and practice: systematic review and meta-analysis

Background: Circulating tumor DNA (ctDNA) has been increasingly used in the clinical care of patients with cancer. This systematic review summarizes current data on the utility of ctDNA in breast cancer clinical research and practice and provides insights for integrating ctDNA into drug development and patient treatment.

Methods: The Embase database was used to identify original clinical research articles of ctDNA in breast cancer published from 2015 to 2020. ctDNA clinical utilities were reviewed and summarized, focusing on 3 areas: early diagnosis, prognostication, and monitoring disease progression/treatment response. Associations of ctDNA with disease-free survival (DFS) and overall survival (OS) were estimated in the embedded meta-analysis. Pooled estimates were calculated using fixed-effect or random-effect models depending on study heterogeneity.

Results: After screening and review, 72 articles were included. ctDNA studies have increased in recent years, with 59.7% of included articles published in 2019 or 2020. Overall, 61.1% of the studies were in patients with advanced stage/metastatic cancer; 45.8% were restricted to patients with specific cancer subtypes. ctDNA was minimally used in diagnosis; it was predominantly used in clinical outcome prediction with differences by stage. In patients with early-stage disease, the meta-analyses found that overall ctDNA detection/positivity was associated with shorter DFS (n=697; HR, 5.37; 95% CI, 2.94-9.80) and OS (n=238; HR, 4.60; 95% CI, 2.56-8.26). Specific gene mutations in ctDNA were mainly assessed in patients with advanced/metastatic disease, with mutations of ERBB, ESR1, and TP53 linked to shorter DFS in the meta-analyses (P<0.05). Moreover, current studies provided evidence that ctDNA reflects the dynamics of breast tumors in the patient treatment journey, acting as a biomarker to monitor tumor evolution and drug resistance.

Conclusions: Recent studies demonstrate ctDNA application in breast cancer prognostication/monitoring, suggesting an important role in patient stratification, molecular relapse identification, and personalized treatment. Large, multicenter clinical trials and real-world longitudinal data sets are needed to validate findings and to address challenges related to ctDNA to improve clinical utility and to integrate ctDNA testing into clinical practice and drug development.

Citation Format: Xuezheng Sun, Nicholas Ballew, Linda Kalilani, Kelesitse Phiri, Kelly Bell, Alexander Slowly, Magdalena Zajac, Erin Hofstatter, Angela Silvestro, Zebin Wang, Jeanne Schilder. Utility of circulating tumor DNA in breast cancer clinical research and practice: systematic review and meta-analysis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6695.

Development and Validation of ICD-10-CM-based Algorithms for Date of Last Menstrual Period, Pregnancy Outcomes, and Infant Outcomes

INTRODUCTION AND OBJECTIVE

Validation studies of algorithms for pregnancy outcomes based on International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) codes are important for conducting drug safety research using administrative claims databases. To facilitate the conduct of pregnancy safety studies, this exploratory study aimed to develop and validate ICD-10-CM-based claims algorithms for date of last menstrual period (LMP) and pregnancy outcomes using medical records.

METHODS

Using a mother-infant-linked claims database, the study included women with a pregnancy between 2016-2017 and their infants. Claims-based algorithms for LMP date utilized codes for gestational age (Z3A codes). The primary outcomes were major congenital malformations (MCMs) and spontaneous abortion; additional secondary outcomes were also evaluated. Each pregnancy outcome was identified using a claims-based simple algorithm, defined as presence of ≥ 1 claim for the outcome. Positive predictive values (PPV) and 95% confidence intervals (CI) were calculated.

RESULTS

Overall, 586 medical records were sought and 365 (62.3%) were adjudicated, including 125 records each for MCMs and spontaneous abortion. Last menstrual period date was validated among maternal charts procured for pregnancy outcomes and fewer charts were adjudicated for the secondary outcomes. The median difference in days between LMP date based on Z3A codes and adjudicated LMP date was 4.0 (interquartile range: 2.0-10.0). The PPV of the simple algorithm for spontaneous abortion was 84.7% (95% CI 78.3, 91.2). The PPV for the MCM algorithm was < 70%. The algorithms for the secondary outcomes pre-eclampsia, premature delivery, and low birthweight performed well, with PPVs > 70%.

CONCLUSIONS

The ICD-10-CM claims-based algorithm for spontaneous abortion performed well and may be used in pregnancy studies. Further algorithm refinement for MCMs is needed. The algorithms for LMP date and the secondary outcomes would benefit from additional validation in a larger sample.

Identification of pregnancies and infants within a United States commercial healthcare administrative claims database

PURPOSE

Health care insurance claims databases are becoming a more common data source for studies of medication safety during pregnancy. While pregnancies have historically been identified in such databases by pregnancy outcomes, International Classification of Diseases, 10^th revision Clinical Modification (ICD-10-CM) Z3A codes denoting weeks of gestation provide more granular information on pregnancies and pregnancy periods (i.e. start and end dates). The purpose of this study was to develop a process that uses Z3A codes to identify pregnancies, pregnancy periods, and links infants within a commercial health insurance claims database.

METHODS

We identified pregnancies, gestation periods, pregnancy outcomes, and linked infants within the United States (US)-based Optum Research Database (ORD) between 2015 and 2020 via a series of algorithms utilizing diagnosis and procedure codes on claims. The diagnosis and procedure codes included ICD-10-CM codes, Current Procedural Terminology (CPT) codes, and Healthcare Common Procedure Coding System (HCPCS) codes.

RESULTS

We identified 1,030,874 pregnancies among 841,196 women of reproductive age. Of pregnancies with livebirth outcomes, 84% were successfully linked to infants. The prevalence of pregnancy outcomes (livebirth, stillbirth, ectopic, molar, abortion) was similar to national estimates.

CONCLUSIONS

This process provides an opportunity to study drug safety and care patterns during pregnancy and may be replicated in other claims databases containing ICD-10-CM, CPT, and HCPCS codes. Work is underway to validate and refine the various algorithms. This article is protected by copyright. All rights reserved.

Cardiovascular Risk in Users of Mirabegron Compared with Users of Antimuscarinic Treatments for Overactive Bladder: Findings from a Non-Interventional, Multinational, Cohort Study

INTRODUCTION

During clinical trials, mirabegron, a β3-adrenoreceptor agonist, was associated with increased vital signs vs placebo in patients with overactive bladder.

OBJECTIVE

The purpose of this study was to compare incidence rates of adverse cardiovascular (CV) outcomes following mirabegron or antimuscarinic use.

METHODS

We conducted an observational post-marketing safety study utilising real-world data. The study population was identified within five sources: Danish and Swedish National Registers, Clinical Practice Research Datalink (UK), Optum (USA) and Humana (USA). Episodes of time when patients were new users of mirabegron or antimuscarinics (October 2012-December 2018) were sourced from prescriptions and matched on propensity scores. Occurrences of major adverse cardiovascular events (MACE), acute myocardial infarction (AMI), stroke, CV mortality and all-cause mortality were identified. Outcome incidence rates and hazard ratios from Cox models were estimated.

RESULTS

Overall, 152,026 mirabegron and 152,026 antimuscarinic episodes were matched. The population consisted of 63.1% women and 72.6% were ≥ 65 years old. There were no appreciable differences in the incidence rates of MACE, AMI or stroke between users of mirabegron and antimuscarinics. Incidence rates of CV mortality (hazard ratio 0.83, 95% confidence interval 0.73-0.95) and all-cause mortality (hazard ratio 0.80, 95% confidence interval 0.76-0.84) were no higher with mirabegron vs antimuscarinics. Results restricted to episodes at high risk for CV events or stratified by age (< 65 years, ≥ 65 years) or prior overactive bladder medication use were consistent with overall findings.

CONCLUSIONS

This large, multinational study found no higher risk of MACE, AMI, stroke, CV mortality or all-cause mortality among users of mirabegron relative to users of antimuscarinics.

Evolution of standard of care therapies used for recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC): A real-world analysis of patient health records from 2016 to 2019

e18728

Background: The R/M HNSCC treatment landscape has evolved significantly in recent years, notably with the approval of 2 immuno-oncology agents (IO), pembrolizumab (second-line [2L] approval, 2016; first-line [1L] approval, 2019) and nivolumab (2L approval, 2016). Review of the literature suggests there is limited real-world (rw) data on clinical outcomes and safety associated with chemotherapy (chemo) and IO in R/M HNSCC. These analyses present a review of patient charts to assess rw clinical outcomes and safety in R/M HNSCC, stratified by patient factors. Methods: Data were derived via structured data extraction and manual review of electronic health records (EHRs; January 1, 2016–December 31, 2019) for patients with R/M HNSCC and who initiated systemic treatment at a community oncology practice in The US Oncology Network. Time-to-event endpoints were assessed by unadjusted Kaplan–Meier analyses and included death (rw overall survival [OS]), provider-assessed progression (rw progression-free survival [PFS]), rw duration of response (DoR), and treatment discontinuation (rw time-to-discontinuation [TTD]). Treatment sequences were evaluated following R/M HNSCC diagnosis. Provider-assessed response rates and adverse events (AEs) as captured in the EHRs were reported. Results: Overall, 257 patients who received 1L treatment were included in these analyses; median age was 64 years (range: 21, 90+); the majority of patients were male (77.4%) and white (74.7%), and 17.5% had evaluable PD-L1 status. The most common 1L treatment regimens were nivolumab (18.3%), carboplatin + paclitaxel (16.0%), and pembrolizumab (14.8%). Median follow-up time from treatment initiation was 7.9 months (range: 0.2, 45.9). Of the 174 patients with evaluable response to 1L treatment, overall response rate was 48.5% (95% CI: 38.3, 58.8) for chemo and 40.0% (95% CI: 28.9, 52.0) for IO. Median rwDoR was 7.6 months (95% CI: 5.8, 11.2). Median rwOS was 12.1 months (95% CI: 10.5, 16.6), and median rwPFS was 5.9 months (95% CI: 4.7, 6.8). Median rwTTD was 2.3 months (95% CI: 2.0, 3.2). The top reason for treatment discontinuation was treatment completion (38.5%) for chemo and progression (46.6.%) for IO. The most commonly reported AEs were rash (17.5%), fatigue (14.4%), and nausea (14.4%) for chemo and fatigue (12.4%), rash (7.2%), and anemia (5.2%) for IO. The percentage of AEs that did not require any intervention was 34.4% for chemo and 20.6% for IO. Conclusions: These analyses present rw clinical outcomes for patients with R/M HNSCC in community oncology practices. The proven role of IO continues to evolve, and continued work is needed to best demarcate the use of these agents, in addition to exploration of additional therapeutics for use in R/M HNSCC. Study funding: GlaxoSmithKline (GSK Study 207139).

A study of cancer occurrence in users of mirabegron and antimuscarinic treatments for overactive bladder

OBJECTIVE

This post-authorization safety study (EU PAS Register Number: EUPAS16088) was designed to compare the incidence of cancer outcomes in patients treated with mirabegron versus antimuscarinic medications.

METHODS

Cohorts of mirabegron initiators during 2012-2018 were propensity-score matched to antimuscarinic medication initiators within real-world data sources (Danish National Registers, Swedish National Registers, Clinical Practice Research Datalink [UK], Optum [US], and Humana [US]). Incident cancer cases were identified during follow-up from direct linkage to cancer registers or validated through medical record review or through physician questionnaires. Comparisons of sex-specific composite cancer outcomes (cancer of the lung/bronchus, colon/rectum, melanoma of skin, urinary bladder, non-Hodgkin lymphoma, kidney/renal pelvis, pancreas, prostate in men and breast and uterus in women) were made overall and for person-time in the first year and after the first year following start of treatment, for all ages and for the subgroup ≥65 years.

RESULTS

Among the 80,637 mirabegron initiators matched to 169,885 antimuscarinic medication initiators, 68% were at least 65 years of age and 66% were women. Over 5000 incident cancer cases were observed overall. Incidence rates were higher for men than women for composite and individual cancer outcomes. The pooled fixed effects hazard ratios for composite cancer outcomes (all ages) were 1.05 (95% confidence interval [CI]: 0.98-1.14) for women and 1.06 (95% CI: 0.98-1.14) for men. Results were similar in persons ≥65 years.

CONCLUSIONS

The results suggest no association between mirabegron use and risk of cancer, compared with antimuscarinic medications, in either men or women. Registration: EU PAS Register Number: EUPAS16088.

Adverse Birth Outcomes in Botswana Among Women With Vertically or Horizontally Acquired Human Immunodeficiency Virus

BACKGROUND

Women with vertically acquired HIV (VHIV) may have a greater risk of adverse birth outcomes than women with horizontally acquired HIV (HHIV).

METHODS

The Tsepamo study performed birth outcomes surveillance at 8 government delivery sites in Botswana from July 2014 through March 2019. Pregnant women diagnosed with HIV before their 11th birthday received VHIV status, and other women had HHIV. Small for gestational age (SGA), preterm delivery (PTD), stillbirth, and neonatal death were compared using χ2 and Fisher's exact tests. Log-binomial regression models determined risk ratios (RRs).

RESULTS

VHIV women (n = 402) aged 15-27 years were identified over 4 years of surveillance and compared with HHIV women (n = 8465) of the same age. VHIV women were more likely to use nevirapine (NVP)-based antiretroviral treatment (ART) in pregnancy and to have SGA and very SGA infants, but less likely to have very PTD infants. In unadjusted analyses, VHIV women had a higher risk of any adverse birth outcome combined (RR = 1.21, 95% confidence interval [CI], 1.08-1.36). After adjusting for potential confounders, particularly use of NVP-based regimens, the risk of adverse birth outcomes among VHIV and HHIV women was similar.

CONCLUSIONS

NVP-based ART is a primary and modifiable risk factor for adverse birth outcomes. Updating ART regimens could improve birth outcomes for women with HIV.

Accuracy of ICD-9-CM coding to identify small for gestational age newborns

PURPOSE

This study aimed to evaluate the accuracy of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code for small for gestational age (SGA) recorded in administrative healthcare records using birthweight and gestational age information recorded in electronic medical records.

METHODS

We used billing and medical records from women aged 13-55 years who delivered at a tertiary care center in the USA between 2004 and 2011. Information on birthweight, gestational age at birth, and ICD-9-CM code for SGA, 656.5x, was abstracted from the database. Each infant's birthweight percentile for gestational age was calculated on the basis of published US references; infants below the 10th percentile were classified as SGA. The performance characteristics of SGA ICD-9-CM diagnosis code against SGA classification based on birthweight and gestational age were calculated, for all deliveries and by strata of demographic and delivery characteristics.

RESULTS

We identified 51 292 singleton live birth deliveries. The prevalence of SGA infants calculated from birthweight and gestational age at birth was higher (13%) than the prevalence based on ICD-9-CM code (2%). Sensitivity of the SGA ICD-9-CM code was 14.2%, specificity was 99.7%, positive predictive value was 86.8%, and negative predictive value was 88.4%. Stratification by demographic and delivery characteristics yielded similar results.

CONCLUSIONS

Identification of SGA infants using ICD-9-CM code, 656.5x, from administrative healthcare records has low sensitivity but high specificity; the accuracy did not differ across demographic and delivery characteristics. Thus, although this source of information would underestimate the prevalence of SGA, it could produce valid relative risk estimates.

Trends in antiretroviral drug use during pregnancy among HIV-infected women on medicaid: 2000-2007

Optimal use of antiretroviral drugs by pregnant women living with human immunodeficiency virus (HIV) is crucial to treat maternal HIV infection and prevent perinatal transmission of the virus effectively. Our goal was to describe national trends of antiretroviral (ARV) use during pregnancy among HIV-infected women living in the U.S. and enrolled in Medicaid. We used the 2000-2007 Medicaid Analytic eXtract (MAX) files to identify our study cohort. ARV use was defined as the dispensing of at least one ARV drug prescription during pregnancy based on Medicaid pharmacy claims. The prevalence of HIV was calculated, and temporal trends of ARV use during pregnancy were compared to the U.S. perinatal treatment guidelines. Predictors of ARV use during pregnancy were assessed using logistic regression models. From 1,106,757 pregnancies (955,251 women), 3083 (2856 women, 0.28%) were identified as HIV positive. We found striking regional variations in the prevalence of HIV and ARV prescription dispensing among pregnant women. The states with the highest HIV prevalence were Washington DC (5.8%), Maryland (0.90%), and New York (0.89%); all other states had a prevalence below 0.5%. A substantial fraction of women did not have any ARV dispensing throughout pregnancy (637 of 3083 (21%) pregnancies), and women with limited health care utilization were the least likely to have ARV dispensings. This finding calls for further research to better characterize HIV-positive women who are enrolled in Medicaid prior to pregnancy and yet have no ARV prescriptions so that appropriate interventions can be implemented.

Reduced tuberculosis case notification associated with scaling up antiretroviral treatment in rural Malawi

OBJECTIVE

To report on the trends in new and recurrent tuberculosis (TB) case notifications in a rural district of Malawi that has embarked on large-scale roll-out of antiretroviral treatment (ART).

METHODS

Descriptive study analysing TB case notification and ART enrolment data between 2002 and 2009.

RESULTS

There were a total of 10,070 new and 755 recurrent TB cases. ART scale-up started in 2003, and by 2007 an estimated 80% ART coverage had been achieved and was sustained thereafter. For new TB cases, an initial increase in case notifications in the first years after starting ART (2002-2005) was followed by a highly significant and sustained decline from 259 to 173 TB cases per 100,000 population (χ(2) for trend 261, P < 0.001, cumulative reduction for 2005-2009 = 33%, 95%CI 27-39). For recurrent TB, the initial increase was followed by a significant drop, from 20 to 15 cases/100,000 (χ(2) for linear trend = 8.3, P = 0.004, constituting a 25% (95%CI 9-49) cumulative reduction between 2006 and 2009. From 2005 to 2009, ART averted an estimated 1164 (95%CI 847-1480) new TB cases and 78 (95%CI 23-151) recurrent TB cases.

CONCLUSIONS

High ART implementation coverage is associated with a very significant declining trend in new and recurrent TB case notifications at population level.

Psychosocial factors affecting medication adherence among HIV-1 infected adults receiving combination antiretroviral therapy (cART) in Botswana

As increasing numbers of persons are placed on potentially life-saving combination antiretroviral therapy (cART) in sub-Saharan Africa, it is imperative to identify the psychosocial and social factors that may influence antiretroviral (ARV) medication adherence. Using an 87 question survey, the following data were collected from patients on cART in Botswana: demographics, performance (Karnofsky) score, perceived stigma and level of HIV disclosure, attitudes and beliefs concerning HIV/AIDS, substance and/or drug use, depression, and pharmacy and healthcare provider-related factors. Overall adherence rates were determined by patient self-report, institutional adherence, and a culturally modified Morisky scale. Three hundred adult patients were recruited between April and May 2005. The overall cART adherence rate was 81.3% based on 4 day and 1 month patient recall and on clinic attendance for ARV medication refills during the previous 3 months. Adults receiving cART for 1-6 months were the least adherent (77%) followed by those receiving cART for greater than 12 months (79%). Alcohol use, depression, and nondisclosure of positive HIV status to their partner were predictive of poor adherence rates (p value <0.02). A significant proportion (81.3%) of cART-treated adults were adherent to their prescribed treatment, with rates superior to those reported in resource-rich settings. Adherence rates were poorest among those just starting cART, most likely due to the presence of ARV-related toxicity. Adherence was lower among those who have been treated for longer periods of time (greater than 1 year), suggesting complacency, which may become a significant problem, especially among these long-term cART-treated patients who return to improved physical and mental functioning and may be less motivated to adhere to their ARV medications. Healthcare providers should encourage HIV disclosure to "at-risk" partners and provide ongoing counseling and education to help patients recognize and overcome HIV-associated stigma, alcohol abuse, and depression.

Effects of HIV type 1 infection on hematopoiesis in Botswana

Clinical observations suggest that HIV-1 infection causes higher anemia rates in patients in southern Africa than in those in the United States. To explore this difference we performed a cross-sectional exploratory study on the effect of HIV-1 infection on hematopoiesis in Botswana by examining hematological presentation, HIV disease state, hematopoietic progenitor cell number, and circulating viral levels in HIV-infected patients and HIV-uninfected controls. We found significant associations between CD34(+) and CD4(+) cell counts in HIV-positive patients. Significant relationships were also seen between the CD34(+) CD4(+) cell population and hemoglobin levels, as well as colony-forming ability. These associations, however, were not seen in uninfected controls. Circulating viral p24 levels were found to correlate significantly with CD34(+) cell count, CD34(+) CD4(+) cell count, and colony-forming ability. These results demonstrate a direct association between HIV-1 infection in southern Africa and hematopoietic progenitor cell health.

Urban/rural differences in prevalence and risk factors for intestinal helminth infection in southern Malawi

Urbanization may increase the risk of human infection with intestinal helminths. A cross-sectional survey was conducted to investigate the prevalence, intensity and potential risk factors of acquiring such infection, among children aged 3-14 years in similar urban and rural communities in southern Malawi. Stool samples were collected from 553 children (273 urban and 280 rural). The overall prevalence of helminth infection was significantly higher in the urban subjects than in the rural (16.5% v. 3.6%; P < 0.001), mostly because of differences in the prevalence of Ascaris lumbricoides infection. Living in an urban community was associated with a significantly higher risk of infection [odds ratio (OR) = 5.3; 95% confidence interval (CI) = 2.6-12.1], even after controlling for potential confounding factors. In the urban community, risk factors included having pools of water/sewage around houses (OR = 3.0; CI = 1.4-6.5), not wearing shoes (OR = 7.1; CI = 2.7-19.2), not attending school (OR = 2.8; CI = 1.2-6.5), having mothers with 4-8 years of education (OR = 5.2; CI = 2.0-14.0), and having mothers below 35 years of age (OR = 4.09; CI = 1.39-16.28). In this part of Africa, efforts to reduce helminth infections may best be focused on reducing geohelminth burden in urban areas.