The Pain Self-Efficacy Questionnaire (PSEQ) is a 10-item self-report questionnaire that measures an individual's confidence in performing daily activities and managing life despite experiencing persistent pain. Each item is measured on a 7-point Likert scale (ranging from 0 to 6). The items assess confidence in performing tasks such as household chores, socializing, working, and coping without medication. A higher total score indicates a stronger belief in managing pain effectively.

The International Physical Activity Questionnaire - Short Form (IPAQ-SF) is an 8-item self-report questionnaire designed to assess the overall physical activity over the past 7 days. Questionnaire items measure the frequency (days) and duration (time) of activities, including walking, moderate-intensity, vigorous-intensity activities, and sedentary behavior.

The Food Frequency Questionnaire (FFQ) consists of 50 food items reflecting the typical dietary intake of Chinese older adults in Hong Kong. The FFQ captures habitual food consumption by combining frequency and portion data to quantify nutrient and food group intake. Participants report the frequency of consumption and portion size for each item, allowing estimation of average daily intake.

The 10-item Perceived Stress Scale (PSS-10) is a self-reported questionnaire that measures the degree to which individuals perceive their lives as unpredictable, uncontrollable, and overloaded over the past month. The items are rated on a 5-point Likert scale from "never" to "very often". Items include six negatively phrased items assessing perceived helplessness and four positively phrased items measuring perceived self-efficacy or coping. Scores for the positively worded items are reverse-coded, and the total score ranges from 10 to 50, with higher scores indicating greater perceived stress.

The 7-item Insomnia Severity Index (ISI) is a self-report questionnaire that assesses the severity and impact of insomnia symptoms. It evaluates difficulties with sleep onset, sleep maintenance, early morning awakening, satisfaction with current sleep patterns, interference with daily functioning, the degree to which the sleep problem is noticeable to others, and the level of distress caused by the sleep problem. Each item is rated on a 5-point scale, ranging from 0 (no problem) to 4 (very severe problem), with total scores ranging from 0 to 28. Higher scores indicate more severe insomnia.

The Lubben Social Network Scale-6 (LSNS-6) is a brief, 6-item self-report questionnaire designed to assess social engagement and the size of social networks among older adults by measuring perceived social support from family and friends. Items include questions on relatives and friends seen or heard from at least once a month, and those the respondent feels comfortable talking to or can call on for help. Scores range from 0 to 30, with higher scores indicating stronger social networks and lower risk of social isolation.

The EuroQuol-5D-5L (EQ-5D-5L) assesses health-related quality of life across five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension has five response levels, ranging from "no problems" to "extreme problems". The questionnaire also includes a visual analogue scale (VAS) for rating overall health on a scale from 0 (worst) to 100 (best).

The participant's past or current history of smoking and the level of alcohol consumption over the past year will be recorded.

Quality-Adjusted Life Years (QALYs) based on the EQ-5D-5L are calculated by multiplying a health utility value, which ranges from 0 (equivalent to death) to 1 (perfect health), by the time spent in that health state. These utility values are derived from the EQ-5D-5L questionnaire responses using country-specific value sets that reflect societal preferences for different health conditions. This calculation provides a combined measure of both the quality and length of life, commonly used to evaluate the effectiveness and cost-efficiency of healthcare interventions.