Bronchiectasis-associated infections and outcomes in a large, geographically diverse electronic health record cohort in the United States.

BACKGROUND: Bronchiectasis is a pulmonary disease characterized by irreversible dilation of the bronchi and recurring respiratory infections. Few studies have described the microbiology and prevalence of infections in large patient populations outside of specialized tertiary care centers. METHODS: We used the Cerner HealthFacts Electronic Health Record database to characterize the nature, burden, and frequency of pulmonary infections among persons with bronchiectasis. Chronic infections were defined based on organism-specific guidelines. RESULTS: We identified 7,749 patients who met our incident bronchiectasis case definition. In this study population, the organisms with the highest rates of isolate prevalence were Pseudomonas aeruginosa with 937 (12%) individuals, Staphylococcus aureus with 502 (6%), Mycobacterium avium complex (MAC) with 336 (4%), and Aspergillus sp. with 288 (4%). Among persons with at least one isolate of each respective pathogen, 219 (23%) met criteria for chronic P. aeruginosa colonization, 74 (15%) met criteria for S. aureus chronic colonization, 101 (30%) met criteria for MAC chronic infection, and 50 (17%) met criteria for Aspergillus sp. chronic infection. Of 5,795 persons with at least two years of observation, 1,860 (32%) had a bronchiectasis exacerbation and 3,462 (60%) were hospitalized within two years of bronchiectasis diagnoses. Among patients with chronic respiratory infections, the two-year occurrence of exacerbations was 53% and for hospitalizations was 82%. CONCLUSIONS: Patients with bronchiectasis experiencing chronic respiratory infections have high rates of hospitalization.

Incidence of Nontuberculous Mycobacterial Pulmonary Infection, by Ethnic Group, Hawaii, USA, 2005-2019.

To further clarify differences in the risk for nontuberculous mycobacterial pulmonary infection (NTM-PI) among ethnic populations in Hawaii, USA, we conducted a retrospective cohort study among beneficiaries of Kaiser Permanente Hawaii (KPH). We abstracted demographic, socioeconomic, clinical, and microbiological data from KPH electronic health records for 2005-2019. An NTM-PI case-patient was defined as a person from whom >1 NTM pulmonary isolate was obtained. We performed Cox proportional hazards regression to estimate incidence of NTM-PI while controlling for confounders. Across ethnic groups, risk for NTM-PI was higher among persons who were underweight (body mass index [BMI] <18.5 kg/m2). Among beneficiaries who self-identified as any Asian ethnicity, risk for incident NTM-PI was increased by 30%. Low BMI may increase susceptibility to NTM-PI, and risk may be higher for persons who self-identify as Asian, independent of BMI.

The 6-minute walk test predicts mortality in a pulmonary nontuberculous mycobacteria-predominant bronchiectasis cohort.

BACKGROUND: Bronchiectasis is a chronic lung condition frequently associated with nontuberculous mycobacteria pulmonary (NTM) disease. Persons with these conditions are at increased risk of mortality. Patient reported outcome (PRO) instruments and the 6-minute walk test (6MWT) have been shown to predict mortality for several lung conditions, but these measures have not been fully evaluated for bronchiectasis and NTM. METHODS: We conducted a retrospective cohort study among adult patients enrolled in a natural history study of bronchiectasis at the National Heart, Lung, and Blood Institute. Electronic medical records were queried for demographic, clinical, microbiologic, radiographic, and PRO instrument data: St. George's Respiratory Questionnaire (SGRQ), Medical Research Council Dyspnea Scale, and the Pulmonary Symptom Severity Score (PSSS). The study baseline date was defined as the patient's first visit after January 1st, 2015 with a SGRQ or 6MWT completed. Follow-up was defined as the interval between the study baseline visit and date of death or December 31st, 2019. Sex-stratified Cox proportional-hazards regression was conducted to identify predictors of mortality. Separate models were run for each PRO and 6MWT measure, controlling for age, body mass index (BMI), fibrocavitary disease status, and M. abscessus infection. RESULTS: In multivariable Cox proportional-hazards regression models, the PSSS-severity (aHR 1.29, 95% CI 1.04-1.59), the 6MWT total distance walked (aHR 0.938, 95% CI 0.896-0.981) and distance saturation product (aHR 0.930, 95% CI 0.887-0.974) independently predicted mortality. In addition, BMI was significantly predictive of mortality in all models. CONCLUSIONS: The 6MWT and a PRO instrument capturing symptom severity are independently predictive of mortality in our cohort of bronchiectasis patients.

Association Between Caseload Surge and COVID-19 Survival in 558 U.S. Hospitals, March to August 2020.

BACKGROUND: Several U.S. hospitals had surges in COVID-19 caseload, but their effect on COVID-19 survival rates remains unclear, especially independent of temporal changes in survival. OBJECTIVE: To determine the association between hospitals' severity-weighted COVID-19 caseload and COVID-19 mortality risk and identify effect modifiers of this relationship. DESIGN: Retrospective cohort study. (ClinicalTrials.gov: NCT04688372). SETTING: 558 U.S. hospitals in the Premier Healthcare Database. PARTICIPANTS: Adult COVID-19-coded inpatients admitted from March to August 2020 with discharge dispositions by October 2020. MEASUREMENTS: Each hospital-month was stratified by percentile rank on a surge index (a severity-weighted measure of COVID-19 caseload relative to pre-COVID-19 bed capacity). The effect of surge index on risk-adjusted odds ratio (aOR) of in-hospital mortality or discharge to hospice was calculated using hierarchical modeling; interaction by surge attributes was assessed. RESULTS: Of 144 116 inpatients with COVID-19 at 558 U.S. hospitals, 78 144 (54.2%) were admitted to hospitals in the top surge index decile. Overall, 25 344 (17.6%) died; crude COVID-19 mortality decreased over time across all surge index strata. However, compared with nonsurging (<50th surge index percentile) hospital-months, aORs in the 50th to 75th, 75th to 90th, 90th to 95th, 95th to 99th, and greater than 99th percentiles were 1.11 (95% CI, 1.01 to 1.23), 1.24 (CI, 1.12 to 1.38), 1.42 (CI, 1.27 to 1.60), 1.59 (CI, 1.41 to 1.80), and 2.00 (CI, 1.69 to 2.38), respectively. The surge index was associated with mortality across ward, intensive care unit, and intubated patients. The surge-mortality relationship was stronger in June to August than in March to May (slope difference, 0.10 [CI, 0.033 to 0.16]) despite greater corticosteroid use and more judicious intubation during later and higher-surging months. Nearly 1 in 4 COVID-19 deaths (5868 [CI, 3584 to 8171]; 23.2%) was potentially attributable to hospitals strained by surging caseload. LIMITATION: Residual confounding. CONCLUSION: Despite improvements in COVID-19 survival between March and August 2020, surges in hospital COVID-19 caseload remained detrimental to survival and potentially eroded benefits gained from emerging treatments. Bolstering preventive measures and supporting surging hospitals will save many lives. PRIMARY FUNDING SOURCE: Intramural Research Program of the National Institutes of Health Clinical Center, the National Institute of Allergy and Infectious Diseases, and the National Cancer Institute.

Antibody responses to the SARS-CoV-2 vaccine in individuals with various inborn errors of immunity.

BACKGROUND: SARS-CoV-2 vaccination is recommended in patients with inborn errors of immunity (IEIs); however, little is known about immunogenicity and safety in these patients. OBJECTIVE: We sought to evaluate the impact of genetic diagnosis, age, and treatment on antibody response to COVID-19 vaccine and related adverse events in a cohort of patients with IEIs. METHODS: Plasma was collected from 22 health care worker controls, 81 patients with IEIs, and 2 patients with thymoma; the plasma was collected before immunization, 1 to 6 days before the second dose of mRNA vaccine, and at a median of 30 days after completion of the immunization schedule with either mRNA vaccine or a single dose of Johnson & Johnson's Janssen vaccine. Anti-spike (anti-S) and anti-nucleocapsid antibody titers were measured by using a luciferase immunoprecipitation systems method. Information on T- and B-cell counts and use of immunosuppressive drugs was extracted from medical records, and information on vaccine-associated adverse events was collected after each dose. RESULTS: Anti-S antibodies were detected in 27 of 46 patients (58.7%) after 1 dose of mRNA vaccine and in 63 of 74 fully immunized patients (85.1%). A lower rate of seroconversion (7 of 11 [63.6%]) was observed in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy. Previous use of rituximab and baseline counts of less than 1000 CD3+ T cells/mL and less than 100 CD19+ B cells/mL were associated with lower anti-S IgG levels. No significant adverse events were reported. CONCLUSION: Vaccinating patients with IEIs is safe, but immunogenicity is affected by certain therapies and gene defects. These data may guide the counseling of patients with IEIs regarding prevention of SARS-CoV-2 infection and the need for subsequent boosts.

Invasive Candidiasis Species Distribution and Trends, United States, 2009-2017.

BACKGROUND: Invasive candidiasis (IC) is a growing concern among US healthcare facilities. A large-scale study evaluating incidence and trends of IC in the United States by species and body site is needed to understand the distribution of infection. METHODS: An electronic medical record database was used to calculate incidence and trends of IC in the United States by species and infection site from 2009 through 2017. Hospital incidence was calculated using total unique inpatient hospitalizations in hospitals reporting at least 1 Candida case as the denominator. IC incidence trends were assessed using generalized estimating equations with exchangeable correlation structure to fit Poisson regression models, controlling for changes in hospital characteristics and case mix over time. RESULTS: Candida albicans remains the leading cause of IC in the United States, followed by Candida glabrata. The overall incidence of IC was 90/100 000 patients, which did not change significantly over time. There were no changes in incidence among C. albicans, C. glabrata, C. parapsilosis, or C. tropicalis; the incidence of other Candida spp. as a whole increased 7.2% annually. While there was no change in candidemia 2009-2017, abdominal and nonabdominal sterile site IC increased significantly. CONCLUSIONS: Nonbloodstream IC is increasing in the United States. Understanding the epidemiology of IC should facilitate improved management of infected patients.

Pharmacoepidemiology of Ceftazidime-Avibactam Use: A Retrospective Cohort Analysis of 210 US Hospitals.

BACKGROUND: Ceftazidime-avibactam has in vitro activity against some carbapenem-resistant gram-negative infections (GNIs), and therefore may be a useful alternative to more toxic antibiotics such as colistin. Understanding ceftazidime-avibactam uptake and usage patterns would inform hospital formularies, stewardship, and antibiotic development. METHODS: A retrospective cohort study assessed inpatient encounters in the Vizient database. Ceftazidime-avibactam and colistin administrations were categorized into presumed empiric (3 consecutive days of therapy or less with qualifying exclusions) versus targeted therapy (≥4 consecutive days of therapy) for presumed carbapenem-resistant GNIs. Quarterly percentage change (QPC) using modified Poisson regression and relative change in frequency of targeted ceftazidime-avibactam to colistin encounters was calculated. Factors associated with preferentially receiving targeted ceftazidime-avibactam versus colistin were identified using generalized estimating equations. RESULTS: Between 2015 quarter (q) 1 and 2017q4, ceftazidime-avibactam was administered 21 215 times across 1901 encounters. Inpatient prescriptions for ceftazidime-avibactam increased from 0.44/10 000 hospitalizations in 2015q1 to 7.7/10 000 in 2017q4 (QPC, +11%; 95% CI, 10-13%; P < .01), while conversely colistin prescriptions decreased quarterly by 5% (95% CI, 4-6%; P < .01). Ceftazidime-avibactam therapy was categorized as empiric 25% of the time, targeted 65% of the time, and indeterminate 10% of the time. Patients with chronic kidney disease were twice as likely to receive targeted ceftazidime-avibactam versus colistin (RR, 2.02; 95% CI, 1.82-2.25), whereas those on dialysis were less likely to receive ceftazidime-avibactam than colistin (RR, 0.71; 95% CI, .61-.83). CONCLUSIONS: Since approval in 2015, ceftazidime-avibactam use has grown for presumed carbapenem-resistant GNIs, while colistin has correspondingly declined. Renal function drove the choice between ceftazidime-avibactam and colistin as targeted therapy.

Extrapulmonary Nontuberculous Mycobacteria Infections in Hospitalized Patients, United States, 2009-2014.

Nontuberculous mycobacteria (NTM) cause pulmonary and extrapulmonary infections in susceptible persons. To characterize the epidemiology of skin and soft tissue (SST) and disseminated extrapulmonary infections caused by NTM in the United States, we used a large electronic health record database to examine clinical, demographic, and laboratory data for hospitalized patients with NTM isolated from extrapulmonary sources during 2009-2014. Using all unique inpatients as the denominator, we estimated prevalence and summarized cases by key characteristics. Of 9,196,147 inpatients, 831 had confirmed extrapulmonary NTM. The 6-year prevalence was 11 cases/100,000 inpatients; source-specific prevalence was 4.4 SST infections/100,000 inpatients and 3.7 disseminated infections/100,000 inpatients. NTM species varied across geographic region; rapidly growing NTM were most prevalent in southern states. Infection with Mycobacterium avium complex was more common among patients with concurrent HIV and fungal infection, a relevant finding because treatment is more effective for M. avium complex than for other NTM infections.

The Impact of Corticosteroids on Secondary Infection and Mortality in Critically Ill COVID-19 Patients.

BACKGROUND: Corticosteroids are part of the treatment guidelines for COVID-19 and have been shown to improve mortality. However, the impact corticosteroids have on the development of secondary infection in COVID-19 is unknown. We sought to define the rate of secondary infection in critically ill patients with COVID-19 and determine the effect of corticosteroid use on mortality in critically ill patients with COVID-19. STUDY DESIGN AND METHODS: One hundred and thirty-five critically ill patients with COVID-19 admitted to the Intensive Care Unit (ICU) at the University of Maryland Medical Center were included in this single-center retrospective analysis. Demographics, symptoms, culture data, use of COVID-19 directed therapies, and outcomes were abstracted from the medical record. The primary outcomes were secondary infection and mortality. Proportional hazards models were used to determine the time to secondary infection and the time to death. RESULTS: The proportion of patients with secondary infection was 63%. The likelihood of developing secondary infection was not significantly impacted by the administration of corticosteroids (HR 1.45, CI 0.75-2.82, P = 0.28). This remained consistent in sub-analysis looking at bloodstream, respiratory, and urine infections. Secondary infection had no significant impact on the likelihood of 28-day mortality (HR 0.66, CI 0.33-1.35, P = 0.256). Corticosteroid administration significantly reduced the likelihood of 28-day mortality (HR 0.27, CI 0.10-0.72, P = 0.01). CONCLUSION: Corticosteroids are an important and lifesaving pharmacotherapeutic option in critically ill patients with COVID-19, which have no impact on the likelihood of developing secondary infections.

Mycobacterial Testing Trends, United States, 2009-20151.

We studied 31 US healthcare facilities to characterize trends in mycobacterial testing. During 2009-2015, testing for acid-fast bacilli increased 3.2% annually, and prevalence of pathogenic nontuberculous mycobacteria increased 4.5% annually. These increases were highest for subpopulations at high risk of infection, including older women, Asians, and patients with concurrent conditions.

Artemisinin-Resistant Malaria as a Global Catastrophic Biological Threat.

The global spread of artemisinin resistance brings with it the threat of incurable malaria. Already, this disease threatens over 219 million lives per year and causes 5-6% losses in GDP in endemic areas, even with current advances in prevention and treatment. This chapter discusses the currently tenuous position we are in globally, and the impact that could be seen if artemisinin treatment is lost, whether due to the unchecked spread of K13 mutations or poor global investment in treatment and prevention advances. Artemisinin is the backbone of current ACT treatment programs and severe malarial treatment; without it, the success of future malaria eradication programs will be in jeopardy.

Dwindling Utilization of Central Venous Catheter Tip Cultures: An Analysis of Sampling Trends and Clinical Utility at 128 US Hospitals, 2009-2014.

At 128 US hospitals, from 2009-2014, a 17% decline occurred annually in central venous catheter tips sent for culture: a 6-fold decrease from blood culture sampling trends. The positive predictive value was low (23%). Tip culture use often does not conform to recommendations and offers limited independent treatment opportunities.

Determinants of bed net use conditional on access in population surveys in Ghana.

BACKGROUND: Insecticide-treated nets (ITNs) are one of the most effective and widely available methods for preventing malaria, and there is interest in understanding the complexities of behavioural drivers of non-use among those with access. This analysis evaluated net use behaviour in Ghana by exploring how several household and environmental variables relate to use among Ghanaians with access to a net. METHODS: Survey data from the Ghana 2014 Demographic and Health Survey and the 2016 Malaria Indicator Survey were used to calculate household members' access to space under a net as well as the proportion of net use conditional on access (NUCA). Geospatial information on cluster location was obtained, as well as average humidex, a measure of how hot it feels, for the month each cluster was surveyed. The relationship between independent variables and net use was assessed via beta-binomial regression models that controlled for spatially correlated random effects using non-Gaussian kriging. RESULTS: In both surveys, increasing wealth was associated with decreased net use among those with access in households when compared to the poorest category. In 2014, exposure to messages about bed net use for malaria prevention was associated with increased net use (OR 2.5, 95% CrI 1.5-4.2), as was living in a rural area in both 2014 (OR 2.5, 95% CrI 1.5-4.3) and 2016 (OR 1.6, 95% CrI 1.1-2.3). The number of nets per person was not associated with net use in either survey. Model fit was improved for both surveys by including a spatial random effect for cluster, demonstrating some spatial autocorrelation in the proportion of people using a net. Humidex, electricity in the household and IRS were not associated with NUCA. CONCLUSION: Net use conditional on access is affected by household characteristics and is also spatially-dependent in Ghana. Setting (whether the household was urban or rural) plays a role, with wealthier and more urban households less likely to use nets when they are available. It will likely be necessary in the future to focus on rural settings, urban settings, and wealth status independently, both to better understand predictors of household net use in these areas and to design more targeted interventions to ensure consistent use of vector control interventions that meet specific needs of the population.

Measuring and characterizing night time human behaviour as it relates to residual malaria transmission in sub-Saharan Africa: a review of the published literature.

BACKGROUND: Malaria cases and deaths decreased dramatically in recent years, largely due to effective vector control interventions. Persistence of transmission after good coverage has been achieved with high-quality vector control interventions, namely insecticide-treated nets or indoor residual spraying, poses a significant challenge to malaria elimination efforts. To understand when and where remaining transmission is occurring, it is necessary to look at vector and human behaviour, and where they overlap. To date, a review of human behaviour related to residual malaria transmission has not been conducted. METHODS: Studies were identified through PubMed and Google Scholar. Hand searches were conducted for all references cited in articles identified through the initial search. The review was limited to English language articles published between 2000 and 2017. Publications with primary data from a malaria endemic setting in sub-Saharan Africa and a description of night time human behaviours were included. RESULTS: Twenty-six publications were identified that met inclusion criteria. Study results fit into two broad categories: when and where people are exposed to malaria vectors and what people are doing at night that may increase their contact with malaria vectors. Among studies that quantified human-vector interaction, a majority of exposure occurred indoors during sleeping hours for unprotected individuals, with some variation across time, contexts, and vector species. Common night time activities across settings included household chores and entertainment during evening hours, as well as livelihood and large-scale socio-cultural events that can last throughout the night. Shifting sleeping patterns associated with travel, visitors, illness, farming practices, and outdoor sleeping, which can impact exposure and use of prevention measures, were described in some locations. CONCLUSIONS: While the importance of understanding human-vector interaction is well-established, relatively few studies have included human behaviour when measuring exposure to malaria vectors. Broader application of a standardized approach to measuring human-vector interaction could provide critical information on exposure across settings and over time. In-depth understanding of night time activities that occur during times when malaria vectors are active and barriers to prevention practices in different contexts should also be considered. This information is essential for targeting existing interventions and development and deployment of appropriate complementary prevention tools.

Difficult-to-Treat Resistance in Gram-negative Bacteremia at 173 US Hospitals: Retrospective Cohort Analysis of Prevalence, Predictors, and Outcome of Resistance to All First-line Agents.

Background: Resistance to all first-line antibiotics necessitates the use of less effective or more toxic "reserve" agents. Gram-negative bloodstream infections (GNBSIs) harboring such difficult-to-treat resistance (DTR) may have higher mortality than phenotypes that allow for ≥1 active first-line antibiotic. Methods: The Premier Database was analyzed for inpatients with select GNBSIs. DTR was defined as intermediate/resistant in vitro to all ß-lactam categories, including carbapenems and fluoroquinolones. Prevalence and aminoglycoside resistance of DTR episodes were compared with carbapenem-resistant, extended-spectrum cephalosporin-resistant, and fluoroquinolone-resistant episodes using CDC definitions. Predictors of DTR were identified. The adjusted relative risk (aRR) of mortality was examined for DTR, CDC-defined phenotypes susceptible to ≥1 first-line agent, and graded loss of active categories. Results: Between 2009-2013, 471 (1%) of 45011 GNBSI episodes at 92 (53.2%) of 173 hospitals exhibited DTR, ranging from 0.04% for Escherichia coli to 18.4% for Acinetobacter baumannii. Among patients with DTR, 79% received parenteral aminoglycosides, tigecycline, or colistin/polymyxin-B; resistance to all aminoglycosides occurred in 33%. Predictors of DTR included urban healthcare and higher baseline illness. Crude mortality for GNBSIs with DTR was 43%; aRR was higher for DTR than for carbapenem-resistant (1.2; 95% confidence interval, 1.0-1.4; P = .02), extended-spectrum cephalosporin-resistant (1.2; 1.1-1.4; P = .001), or fluoroquinolone-resistant (1.2; 1.0-1.4; P = .008) infections. The mortality aRR increased 20% per graded loss of active first-line categories, from 3-5 to 1-2 to 0. Conclusion: Nonsusceptibility to first-line antibiotics is associated with decreased survival in GNBSIs. DTR is a simple bedside prognostic measure of treatment-limiting coresistance.

Epidemiology of Nontuberculous Mycobacteriosis.

Annual prevalence estimates for pulmonary nontuberculous mycobacterial (PNTM) disease in the contiguous United States range from 1.4 to 13.9 per 100,000 persons, while one study found an annual prevalence of up to 44 per 100,000 persons in Hawaii. PNTM prevalence varies by region, sex, and race/ethnicity, with higher prevalence among women and persons of Asian ancestry, as well as in the Southern United States and Hawaii. Studies consistently indicate that PNTM prevalence is increasing, with estimates ranging from 2.5 to 8% per year. Most PNTM disease is associated with Mycobacterium avium complex (MAC), although the proportion of disease attributed to MAC varies by region. Host factors identified as influencing disease risk include structural lung disease, immunomodulatory medication, as well as variants in connective tissue, mucociliary clearance, and immune genes. Environmental variables including measures of atmospheric moisture and concentrations of certain soil factors have also been shown to correlate with higher PNTM prevalence. Prevalence of extrapulmonary NTM disease is lower, stable, and associated with different risk factors, including primary immune deficiencies or HIV infection.

Associations between ideational variables and bed net use in Madagascar, Mali, and Nigeria.

BACKGROUND: The use of insecticide-treated bed nets (ITNs) is crucial to the prevention, control, and elimination of malaria. Using household surveys conducted in 2014-2015 by the Health Communication Capacity Collaborative project in Madagascar, Mali, and Nigeria, we compared a model of psychosocial influence, called Ideation, to examine how malaria-related variables influence individual and household bed net use in each of these countries. Evaluations of non-malaria programs have confirmed the value of the ideational approach, but it is infrequently used to guide malaria interventions. The study objective was to examine how well this model could identify potentially effective malaria prevention approaches in different contexts. METHODS: Sampling and survey designs were similar across countries. A multi-stage random sampling process selected female caregivers with at least one child under 5 years of age for interviews. Additional data were collected from household heads about bed net use and other characteristics of household members. The caregiver survey measured psychosocial variables that were subjected to bivariate and multivariate analysis to identify significant ideational variables related to bed net use. RESULTS: In all three countries, children and adolescents over five were less likely to sleep under a net compared to children under five (OR = 0.441 in Madagascar, 0.332 in Mali, 0.502 in Nigeria). Adults were less likely to sleep under a net compared to children under five in Mali (OR = 0.374) and Nigeria (OR = 0.448), but not Madagascar. In all countries, the odds of bed net use were lower in larger compared to smaller households (OR = 0.452 in Madagascar and OR = 0.529 in Nigeria for households with 5 or 6 members compared to those with less than 5; and OR = 0.831 in Mali for larger compared to smaller households). Of 14 common ideational variables examined in this study, six were significant predictors in Madagascar (all positive), three in Mali (all positive), and two in Nigeria (both negative). CONCLUSION: This research suggests that the systematic use of this model to identify relevant ideational variables in a particular setting can guide the development of communication strategies and messaging, thereby improving the effectiveness of malaria prevention and control.

Demand and willingness-to-pay for bed nets in Tanzania: results from a choice experiment.

BACKGROUND: Universal coverage campaigns for long-lasting insecticide-treated nets do not always reach the goal of one net for every two household members, and even when ownership of at least one net per household is high, many households may not own enough nets. The retail market provides these households options for replacing or increasing the number of nets they own with products that best fit their needs since a variety of net shapes, sizes, and colours are available. Hence, it is important to understand the factors affecting private net demand. This study explores private demand for nets in Tanzania using a discrete choice experiment. The experiment provides participants the option to buy nets with their own money, and thus should prove more accurate than a hypothetical survey of net preferences. RESULTS: Nearly 800 participants sampled in two regions showed an overall strong demand for nets, with 40% choosing to buy a net across all seven combinations of net prices and characteristics such as size, shape, and insecticide treatment. Only 8% of all participants chose not to buy a single net. A key factor influencing demand was whether a participant's household currently owned sufficient nets for all members, with rural participants showing lower net coverage and greater demand than urban participants. Both poor and less poor households showed strong evidence of making purchase decisions based on more than price alone. Mean willingness-to-pay values for a net started at US$1.10 and grew by US$0.50-1.40 for various attributes such as rectangular shape, large size, and insecticide treatment. The impact of price on demand was negative but small, with elasticity values between -0.25 and -0.45. CONCLUSIONS: The results suggest that private demand for nets in Tanzania could potentially supplement future coverage campaigns. Net manufacturers and retailers should advertise and promote consumers' preferred net attributes to improve sales and further expand net access and coverage. To overcome household liquidity concerns and best replicate the experiment results, policy makers should consider making credit available for interested buyers.

The use of mediation analysis to assess the effects of a behaviour change communication strategy on bed net ideation and household universal coverage in Tanzania.

BACKGROUND: SBCC campaigns are designed to act on cognitive, social and emotional factors at the individual or community level. The combination of these factors, referred to as 'ideation', play a role in determining behaviour by reinforcing and confirming decisions about a particular health topic. This study introduces ideation theory and mediation analysis as a way to evaluate the impact of a malaria SBCC campaign in Tanzania, to determine whether exposure to a communication programme influenced universal coverage through mediating ideational variables. METHODS: A household survey in three districts where community change agents (CCAs) were active was conducted to collect information on ITN use, number of ITNs in the household, and perceptions about ITN use and ownership. Variables relating to attitudes and beliefs were combined to make 'net ideation'. Using an ideational framework, a mediation analysis was conducted to see the impact exposure to a CCA only, mass media and community (M & C) messaging only, or exposure to both, had on household universal coverage, through the mediating variable net ideation. RESULTS: All three levels of exposure (CCA, M & C messaging, or exposure to both) were significantly associated with increased net ideation (CCA: 0.283, 95% CI: 0.136-0.429, p-value: <0.001; M & C: 0.128, 95% CI: 0.032-0.334, p-value: 0.018; both: 0.376, 95% CI: 0.170-0.580, p-value: <0.001). Net ideation also significantly increased the odds of having universal coverage (CCAOR: 1.265, 95% CI: 1.118-1.433, p-value: <0.001; M & COR: 1.264, 95% CI: 1.117-1.432, p-value: <0.001, bothOR: 1.260, 95% CI: 1.114-1.428, p-value: <0.001). There were no significant direct effects between any exposure and universal coverage when controlling for net ideation. CONCLUSIONS: The results of this study indicate that mediation analysis is an applicable new tool to assess SBCC campaigns. Ideation as a mediator of the effects of communication exposure on household universal coverage has implications for designing SBCC to support both mass and continuous distribution efforts, since both heavily rely on consumer participation to obtain and maintain ITNs. Such systems can be strengthened by SBCC programming, generating demand through improving social norms about net ownership and use, perceived benefits of nets, and other behavioural constructs.