In this cross-sectional, inter-country comparison using independent samples, the data from two relatively similar risk factor and chronic disease surveillance systems have been utilised.
SAMSS is an ongoing telephone surveillance system designed to regularly monitor chronic disease, risk factors and other health-related issues . Commencing in July 2002, a cross-sectional sample is randomly selected each month from all households in SA with a telephone number listed in the Electronic White Pages (EWP). A letter of introduction is sent to the selected household and the person who was last to have a birthday is chosen for interview.
Trained interviewers, via a Computer Assisted Telephone Interview (CATI) system, conducts the interviews in English. Each interview takes approximately 15–20 min. At least ten call-backs are made to the telephone number selected. Replacement interviews for persons who could not be contacted or interviewed are not permitted. A minimum of 600 randomly selected people (of all ages) are interviewed each month. The current analysis used data collected from July 2002 to December 2015 for respondents aged 40–69 years. The response rates of SAMSS for this period ranged between 51.4 and 75.2% (median = 64.9). All respondents gave informed consent to undertaking the interview. Ethics approval was obtained from the ethics committee of the Department of Health and Ageing, SA (HREC Number 14/SAH/200). Other details on SAMSS are available elsewhere .
PASSI was established in 2007 and is based on data collected via Local Health Units (LHU) each month. Primary approach letters are sent to each selected person. Data are collected in each of the 21 Italian regions via telephone calls from trained LHU staff and a random sample of 18 to 69 years adults are interviewed each month. At least six call-backs are made before selecting a substitute person of the same sex and age group. A national centre coordinates data management. Response rates are high (80+%). The interview takes approximately 20 min. Ethics approval was obtained from the Ethical Commission of the Istituto Superiore di Sanita (The Italian National Institute for Health). Other details on PASSI methodology are available elsewhere [16,17,18].
For both datasets body mass index (BMI) was derived from self-reported weight and height and recoded into three categories (underweight/normal, overweight and obese) . Respondents were asked the number of serves of fruit and vegetables consumed each day with SAMSS being two separate questions and PASSI combining the questions into one. These questions were recoded into inadequate fruit and vegetable consumption (<5 vegetables and/or fruits per day) [16, 20].
Regarding physical activity, the SA respondents were asked the time spent undertaking walking, moderate or vigorous physical activity over the past week. To determine if respondent’s level of physical activity is sufficient to provide a health benefit, sufficient physical activity was defined has having 150 min or more of total time spent with vigorous activity multiplied by a factor of two to account for its greater intensity. The respondents were then classified as undertaking no activity, activity but not sufficient and sufficient activity . PASSI participants were asked on how many days and for how long they undertook moderate and vigorous activity. Respondents with no activity, or activity but not sufficient activity, were classified as insufficient physical activity in order to allow PASSI data to be compared to the SA data.
SA included two alcohol questions recommended by the [Australian] National Health and Medical Research Council . These are ‘how often do you drink alcohol’ and ‘on a day when you drink alcohol how many drinks do you usually have’. PASSI respondents were asked ‘during the past 30 days how many days did you have at least one drink of any alcohol beverage’ and ‘how many drinks did you drink on average’ . Respondents who drank two or more standard drinks on any day were classified into a risky category.
PASSI respondents who reported smoking at least 100 cigarettes in their lifetime and who smoked either every day or some days were defined as current smokers. Respondents who reported smoking at least 100 cigarettes in their lifetime and not smoked in the previous 6 months were ex-smokers. Non-smokers were those never smoked 100 cigarettes. For SAMSS, smoking status (current, ex or non) was assessed by a single question. The proportion of current smokers for both data-sets was assessed.
All respondents were asked if they had ever been told by a doctor they had diabetes. They were also asked if a doctor told them they had high blood pressure (HBP) or high cholesterol and/or were on medication for the condition. Respondents were considered as having at least one risk factor if they had at least one of the following; current HBP, current high cholesterol, insufficient physical activity, overweight/obese, current smoker, risky alcohol intake, or insufficient fruit and vegetable consumption.
SA respondents were asked to rate their health as poor, fair, good, very good or excellent. PASSI respondents rated their current health status as excellent, good, fair, poor or very poor. A self-reported health status variable was created comparing SA poor overall health status with very poor for PASSI.
Comparable demographic and socioeconomic variables included age, gender, work status, highest education attainment, marital status, and the number of days in the previous 4 weeks (30 days) the respondent had been unable to work or carry out normal duties because of health.
Both samples were weighted to correct for disproportionality of the sample with respect to the population of interest and to allow for some of the bias to be compensated as a result of the non-contacted households or for any gender or age-group discrepancies. The SAMSS data were weighted each month by age, sex and area of residence to reflect the structure of the population in SA to the latest Australian Bureau of Statistics (ABS) Census data, and probability of selection in the household. Approximately 60–70% of the total SA households are included in the EWP. PASSI data were weighted by gender and age at the regional level based on annual Italian National Institute of Statistics figures to compensate for different sampling proportion in the LHU (covering over 90% of the residents in Italy). Eligible respondents are randomly selected from the LHU registries, and as no citizen can access any health service without being registered, the registries are highly reliable and regularly updated .
Data were analyzed using SPSS for Windows Version 20.0 and Stata Version 9.2. The analyses for SAMSS was limited to 40 to 69 years of age as PASSI upper age limit is 69 years. The lower age was determined because of the relatively skewed older Italian-born Australians owing to the decline in migration from Italy to Australia in recent decades compared to early post-war decades. For PASSI 2007 data was excluded since the PASSI system not being national until 2008. The SAMSS data included data from July 2002 and was limited to respondents born in Australia, and the PASSI data to those born in Italy. Data were age-adjusted to the World Health Organization (WHO) world standard population by a direct standardization method.