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Table 1 Instruments used in the survey (computer-assisted face-to-face data collection)

From: National survey of the Portuguese elderly nutritional status: study protocol

Assessed Constructs Questionnaire/measure scale Description
Health status self-perception General self-rated health status Single-item scale, with a five-point scale of answer, from 1 “Poor” to 5 “Excellent” health. This question is extensively used, and is a key predictor of severe morbidity and even mortality [32]. It is also often used as a component of the health-related quality of life, included in the Medical Outcome Study Short Form 36 (MOS SF-36) scale. Its psychometric properties were described for Portugal [33].
Physical activity IPAQ: International Physical Activity Questionnaire, short form This is a 9-items scale, providing information on the time spent walking, in vigorous and moderate intensity activities and in sedentary activities. It is validated for the Portuguese population [34, 35]. Additional questions regarding number of sleeping hours, physical activity associated with daily tasks, identification of the leisure and programmed physical activity were added.
Food consumption and food patterns 24 h recall Dietary assessment will be performed by using a 24 h recall interview. In this interview, respondents are inquired about the food consumed in the previous 24 h, in two random non-consecutive days, without prior notification, within a timeframe between 8 and 15 days.
Portion size estimation will be performed by using food pictures and standardized household measures integrated in the software “YOU, eAT&Move”. The software automatically calculates total nutrient intake. All the methodology was developed in the scope of IAN-AF, following the methodology proposed by the European Food Safety Authority (EFSA) in the pan-European Survey EU-MENU [36].
A Food Propensity Questionnaire (FPQ) will be used to complement the 24 h recall. The FPQ includes a list of 79 food items (including alcoholic beverages), consumed in the last 12 months. For each item, there is a frequency-based ordinal scale, with nine possible responses ranging from “never” to “6-7 days/week”. The FPQ was adapted by the IAN-AF team, following the protocol proposed by the Food Consumption Data Collection Methodology for the EU Menu Survey (Pilot-PANEU) [36, 37].
Food Propensity Questionnaire
Food insecurity   Food insecurity as a measure of hunger due to income limitations represents the condition of the household members as a group. This is a continuous, linear scale [3840].
Anthropometric measurements Weight
Height
Waist, hip, arm and calf circumferences.
Individuals wearing minimal clothing without shoes will be measured to the nearest 0.1 kg with a portable calibrated scale (SECA Robusta 813®).
Height will be measured without shoes using a portable stadiometer to the nearest 0.1 cm (SECA 214®). Whenever collection of height using the stadiometer is not possible, estimation of height will be done through hand length. This will be measured using a fiberglass tape to the nearest 0.1 cm and a validated equation for the Portuguese population [41].
Waist, hip, arm and calf circumferences to the nearest 0.1 cm will be measured with a non-extensible, flexible, fiberglass tape (SECA 201®).
All measurements will be performed according to a standard interviewer manual based on the International Standards for Anthropometric Assessment (ISAK) [42].
Nutritional status MNA®:
Mini Nutritional Assessment
This is the most widely used and validated screening method for identification of frail elderly and geriatric population at nutritional risk. It is recommended by different national and international clinical and scientific organizations as a community useful clinical tool. It is composed by 18-items, giving a maximum score of 30 points. The cut-off of below 24 points is used to identify individuals at-risk and to predict poor outcomes in the elderly [4345]. This instrument is validated for the Portuguese population [46].
Cognitive function MMSE:
Mini-Mental State Examination
This is one of the most widely used instruments in epidemiological studies, as a screening of cognitive impairment. It includes 30 items, assessing temporal and spacial orientation, working memory, recall, attention, arithmetic capacity, linguistic, and visual-motor skills. The maximum score is 30 points (one point per correct item). The minimum cut-off for adequate cognitive functioning is set accordingly to the level of education of the participant [47, 48].
The psychometric properties of the MMSE for the Portuguese population were previously described [49].
Emotional status GDS: Geriatric Depression Scale, Short Form This is a 15-items instrument to screen for clinical depression among elderly. It excludes somatic symptoms that might be due to medical illness, and makes use of a simple response format: yes/no. The sum of scores allows the categorization of respondents in terms of depressed or non-depressed. The development, validation and factor structure of the shorter GDS-15 was described and evaluated in nursing home populations [50, 51]. The psychometric properties of the MMSE for the Portuguese population were previously described [52].
Loneliness UCLA Loneliness Scale This is a 16-items scale, with a 4-points Likert-type answer of format (from 1 “never” to 4 “frequently”) which measures loneliness. Scores range from 16 to 64 points (the highest the value the highest the subjective feeling of loneliness or social isolation) [53, 54]. The psychometric properties of the UCLA Loneliness Scale for the Portuguese population were previously described [55].
Functionality Lawton Scale This scale measures the instrumental daily living activities of the elderly. It is an 8-itens scale, with a polycotomic format of response, allowing the evaluation of the elderly autonomy to conduct daily life activities. Scores range from 0 to 8 [56]. The psychometric properties of the Lawton Scale for the Portuguese population were previously described [57].