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Purpose: Field substitution of nonrespondents can be used to maintain the planned sample size and structure in surveys but may introduce additional bias. Sample weighting is suggested as the preferable alternative; however, limited empirical evidence exists comparing the two methods. We wanted to assess the impact of substitution on surveillance results using data from Progressi delle Aziende Sanitarie per la Salute in Italia-Progress by Local Health Units towards a Healthier Italy (PASSI)., Methods: PASSI is conducted by Local Health Units (LHUs) through telephone interviews of stratified random samples of residents. Nonrespondents are replaced with substitutes randomly preselected in the same LHU stratum. We compared the weighted estimates obtained in the original PASSI sample (used as a reference) and in the substitutes' sample. The differences were evaluated using a Wald test., Results: In 2011, 50,697 units were selected: 37,252 were from the original sample and 13,445 were substitutes; 37,162 persons were interviewed. The initially planned size and demographic composition were restored. No significant differences in the estimates between the original and the substitutes' sample were found., Conclusions: In our experience, field substitution is an acceptable method for dealing with nonresponse, maintaining the characteristics of the original sample without affecting the results. This evidence can support appropriate decisions about planning and implementing a surveillance system., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Monitoring perceptions, knowledge, attitudes and behaviors of populations during pandemic flu outbreaks is important as it allows communication strategies to be adjusted to meet emerging needs and assessment to be made of the effects of recommendations for prevention. The ongoing Italian Behavioral Risk Factor Surveillance System (PASSI) offered the setting for investigating people's opinions and behaviors regarding the A/H1N1 pandemic. PASSI surveillance is carried out in 126/148 Italian Local Health Units (LHU) through monthly telephone interviews administered by public health staff to a random sample of the resident population 18-69 years. In fall 2009 additional questions exploring issues related to the A/H1N1 flu were added to the standard questionnaire. The pandemic module was administered on a voluntary basis by the 70 participating LHUs from November 2nd, 2009 to February 7th, 2010; 4 047 interviews were collected. Overall 33% of respondents considered it likely that they would catch flu, 26% stated they were worried, 16% reported having limited some daily activities out of home and 22% said they would accept vaccination if offered. All these indicators showed a decreasing trend across the four-month period of observation. The most trusted sources of information were family doctors (81%). Willingness to be vaccinated was associated with worry about pandemic, age, sex, having a chronic disease and timing of the interview. The surveillance allowed us to gather relevant information, crucial for devising appropriate public health interventions. In future disease outbreaks, systems monitoring people's perceptions and behaviors should be included in the preparedness and response plans.

Introduction: Surveillance systems for health status and behaviors of populations are fundamental for planning, implementing, and monitoring preventive interventions. In 2006, the Italian Ministry of Health provided funding to the National Institute of Public Health to develop an ongoing surveillance system for adult behavioral risk factors. We describe the main features of the system (known as PASSI) and provide a preliminary assessment of its activity., Methods: PASSI is conducted by participating local health units, which use a common questionnaire and methods. Each month, local health unit staff conduct telephone interviews of a random sample of resident adults aged 18 to 69 years. Data are transmitted to the national coordinating center, where they are cleaned, managed, and made available for local, regional, and national analysis. Training, data analysis, and communications are centrally supervised, and data quality is routinely monitored., Results: In 2007 and 2008, nearly 60,000 interviews were completed. The demographic characteristics of survey participants closely corresponded to census data in the surveyed areas. The response rate was 82%; the refusal rate was 10% or less. Communications activities have been conducted to disseminate the results and encourage their use., Conclusion: PASSI is administered by the public health system with limited human and financial resources. In the first 2 years of activity, the data quality was good, and information collected was useful. The organizational model of PASSI may be of interest to countries that are developing surveillance systems as well as those with systems already in place.