Cohort Profile: The IRanian Longitudinal Study on Ageing (IRLSA): the first comprehensive study on ageing in Iran

The IRanian Longitudinal Study on Ageing (IRLSA) is the ageing component of the nationwide PERSIAN Cohort and aims to comprehensively assess the different aspects of ageing (age 50 to 95), monitor the changes in health and well-being of older adults and evaluate differing needs during the ageing transition. We aimed to recruit up to 20 000 participants from four different sites of study, including Neyshabur (Razavi Khorasan province, northeast of Iran), Guilan (northern Iran), Tabriz (northwest of Iran) and Ardakan (central Iran), to include people from different ethnicities and geographical areas. A total of 7462 individuals (4831 households, 3962 women; 3500 men) provided written consent to participating in the Neyshabur study site. Data collection included a comprehensive questionnaire on demographic, socioeconomic, lifestyle, physical and psychological aspects, clinical examination, mobility assessment and anthropometric measures. There is a biobank including different biological samples (blood, urine, nail, hair and stool). The data for the registration phase of the Neyshabur study site were collected during 2016–18. Information on study details and data access forms can be found on the study website [https://nelsacohort.nums.ac.ir, https://persiancohort.com] or through sending an e-mail to [email protected] or the principal investigator of IRLSA Nayyereh Aminisani [[email protected]]. The age distribution in Iran is changing; soon we will face an ageing population.1,2 Non-communicable diseases such as cardiovascular diseases, cancer, diabetes and osteoporosis more commonly affect adults and older people.3 These diseases are associated with a range of risk factors, such as smoking, hypertension, hypercholesterolaemia, inadequate physical activity and overweight/obesity, that are mostly preventable.4 Also, older people are more likely to experience frailty, loneliness, depression/emotional distress, economic insecurity/poverty, functional limitation/disability and need for help for daily activities.5–11 Many studies have been conducted in Iran to examine different aspects of heath in the older population. However, most of them have been cross-sectional, focused on a specific feature of ageing, small in sample size or conducted in a non-representative sample of older adults, weaknesses that make it difficult to generalize findings or translate them into policy. Cohort studies among older adults in Iran are scarce.12,13 Those studies that exist either focus on a specific outcome (e.g. Busher cohort study including 3000 people in the south of Iran, focusing on cardiovascular diseases) or include a relatively small population (e.g. Amirkola ageing study in the north of Iran with a sample size of ∼ 1200 people). Moreover, these studies only include individuals aged 60 years and over, which does not allow us to look at how factors in late mid-life, e.g. employment, might affect later life. In order to assess the dynamic ageing process, it is necessary to include people from middle age, e.g. 45 or 50 years old onwards. This is in line with other cohort studies of older adults, e.g. the Health and Retirement Study in the USA, the China Health and Retirement Longitudinal Study (CHARLS), and the Canadian Longitudinal Study on Aging (CLSA). Therefore, there is a need for a comprehensive and multidisciplinary longitudinal study to understand better the older population’s health, well-being and health care needs in Iran. The Prospective Epidemiological Research Studies in IrAN (PERSIAN) is a nationwide cohort study launched in 2014 to bring together research in the fields of medicine, epidemiology, health and nutrition.14 The PERSIAN Cohort is the first national prospective cohort study that aims to include 200 000 men and women between 35 and 70 years of age from 18 sites throughout the country, focusing on non-communicable diseases and their associated risk factors [www.persiancohort.com]. They are being followed up for 15 years. In parallel with the adult component of PERSIAN, several other components have been initiated, such as the ‘Older Adults Cohort’, the ‘Birth Cohort’ and the ‘Youth Cohort’. These cohorts allow researchers to investigate the health needs of various population groups and age ranges; however, due to limited resources, they are being conducted in selected sites but follow the same governance and research quality. The ageing component of the PERSIAN Cohort, also known as ‘IRanian Longitudinal Study on Ageing (IRLSA)’, is a comprehensive assessment of the different aspects of ageing (ages 50 to 95), monitoring the changes in health and well-being as well as evaluating differing needs during the ageing transition. IRLSA consists of two modes of data collection: (i) in-depth, comprehensive data collection, which includes one home visit and two clinic visits; (ii) core data collection, including a home visit and only one clinic visit. There are many similarities in questionnaires and measurements across the two modes of data collection; however in the in-depth data collection, participants underwent more laboratory tests and clinical examinations (described in detail in the Data Collection section below). Participants were invited randomly from the pre-existing sample list to either the in-depth or the core data collection group. The PERSIAN Ageing Cohort was first launched in Neyshabur (Razavi Khorasan province, northeastern Iran) andin late 2019 extended into three other sites: Guilan (northern Iran), Tabriz (northwestern Iran) and Ardakan (central Iran) to include people from different ethnicities and geographical areas. The main site of the study is Neyshabur city, located in the northeast of Iran, with a total population of about 200 000. Neyshabur is an old city, dominated by individuals of Persian ethnicity who follow a lifestyle similar to large urban areas of Iran. The health care system in this city is well established to perform follow-ups on cohort participants. At the time of the study commencement, about 11% of Neyshabur’s population were aged 60 years and older; these individuals came from various levels of socioeconomic status (Supplementary Figure S1, available as Supplementary data at IJE online). General objectives of the study are as follows: to describe the socioeconomic status, health and well-being of older people; to monitor changes in health and well-being, and assess needs during the ageing transition (by forming a longitudinal database including a range of socioeconomic, behavioural and environmental factors, health care access and biomarkers); to identify the demographic, socioeconomic and health-related factors associated with changes in physical and mental health and social engagement/exclusion among older adults; to explore the relationships/interrelationships between a range of risk factors/protective factors and healthy ageing and longevity; to identify high-risk groups as targets for preventive strategies and individualized care; to determine the basic infrastructure needs (social needs, home care etc.), in order to improve the current system or promote new initiatives for the older population in Iran. The primary outcomes of interest in IRLSA, include: frailty/disability; morbidity/multimorbidity, and mortality from common chronic diseases; hospitalization and institutionalism; changes in health needs over time. The Neyshabur cohort has been approved by the Ethical Committee of Neyshabur University of Medical Sciences (record number IR.NUMS.REC, 1394.35) and the PERSIAN cohort study ethics approval by Tehran University of Medical Sciences (record number IR.TUMS.DDRI.REC.1396.1). Written informed consent was obtained from all participants and they were free to leave the study at any time and for any reason, without any consequences. The participants of this study were men and women 50–95 years of age with a minimum 3-year residency in Neyshabur, who were Iranian citizens (according to the national ID card and birth certificate) and without dementia, major depression or disabilities which would limit their ability to participate in the study. Participants were selected through stratified random sampling from the list of people registered with six health centres in the inner city of Neyshabur, where more than 75% of the population in the target age range resides. For easier follow-up, remote or newly developed urban areas were excluded due to the mobility of the population and transport difficulties (Supplementary Figure S2, available as Supplementary data at IJE online). Since the age distribution of people registered with health centres was diverse, stratified random sampling was used first to select each stratum based on the proportion of people aged 50–95 years. In each stratum, a simple random sampling method was used to choose the prospective study population. Based on our available research grant, we aimed to recruit about 8000 individuals. All household members aged ≥50 years were eligible to participate in the study. In the health centres’ census list there were 16 569 households in which the head of the family was ≥50 years of age; random phone calls were initiated for 7000 households, including 11 247 people in the target age range. A total of 9220 people met the eligibility criteria, of whom a total of 7462 individuals (4831 households) provided written consent to participate in the study. The pilot phase was conducted to assess the feasibility and validation of selected tools such as the Montreal Cognition Assessment (MoCA),15 Physical Activity for Elderly (PASE),16 loneliness,17 short-form food frequency for older adults and short nutrition screening questionnaire (SCREEN II).18 The pilot phase commenced in January 2016 and was completed in 3 months, including 350 people who were selected randomly from the main list. During the pilot phase, arrangement for clinic visits, interview time, client’s convenience for transport and waiting time were also assessed, to improve data collection in the main enrolment phase. The enrolment phase began in April 2017 and was completed in January 2018, when the target sample of 7462 had been enrolled. We first started enrolling for the in-depth data collection method and enrolled about 4100 participants; subsequently, about 3400 participants were enrolled for the core assessment method. The participation rate was 81%. On average, there were 3.06 ± 1.15 individuals per household. We plan to follow up participants every 2 years for core information, including sociodemographic, lifestyle, psychological, cognition and social factors, health service use and routine measurements. Blood pressure and anthropometric measurements, routine laboratory tests and mobility tests are conducted as well. The comprehensive assessment of biomarkers and clinical examinations will be delivered every 4 years for at least 12 years. All follow-up assessment will be done in the same cohort centre at each site of the study (Supplementary Figure S2). The outcomes of interest in this study are hospitalization, institutionalism, deaths, physical limitation/disabilities, fractures, falls, health service use and a range of chronic diseases. Cardiovascular diseases, cancers, diabetes mellitus, chronic pulmonary diseases, chronic kidney disease leading to dialysis, cirrhosis of the liver, Parkinson’s disease and Alzheimer’s disease are the important chronic diseases evaluated. In addition to active follow-up, a passive mode of follow-up will be used, including reports from disease and death registries. In case of occurrence of any of the outcomes of interest, a trained nurse reviews all documents and makes contact with pertinent hospitals and clinics to investigate any incomplete records make copies of relevant documents. If death is reported, our trained nurses will complete a verbal autopsy form. There will be a biobank including six samples (four plasmas, two whole bloods, and a subsample of DNA) for participants enrolled in the in-depth study group. To assess the longitudinal changes in biospecimens, this will be repeated at first follow- up and in the 8th year, depending on the availability of funding. Participation in the study ceases if a person stops collaboration with the study team, moves away from the study area or death is reported. If a participant is incapacitated and unable to complete all parts of the follow-up session because of any health problem, a family member will be asked to serve as a proxy respondent for the essential information such as new diagnosis, hospitalization, physical limitation and psychosocial questions (nomination of the proxy is sought at enrolment). If the participant is unwilling to continue, the study team will re-invite the subject, briefing them on the benefits of participation in the research, including the promotion of personal and public health and mostly free medical and laboratory services at the study centre. The first 2-yearly follow-up began in 2019 when all participants (n = 7462) were invited to the cohort centre and requested to bring all medical documents and medications with them. Our trained nurses assess documents and follow each case (in person) in all hospitals and clinics to collect relevant laboratory results, medical documents and medications. In case of incomplete documents, they follow each person by contacting hospitals, registries and death centres to order a copy of relevant documents. Then data are recorded in follow-up forms, with the initial outcome of interest to be assessed by the reviewing physicians at the outcome review committee to confirm the diagnosis. They are asked about the occurrence of any of the study’s outcomes of interest, and trained nurses check all clinical reports and medications. A phone interview is arranged upon completion of the centre visit, for the completion of the general questionnaire. For those participants who are unable to be interviewed by phone, or have a hearing problem, the interview is performed by trained interviewers during their visit to the centre. Information for 5716 participants has been completed so far (30 September 2021). Data on a wide range of different factors including economic, social, psychological, cognitive, health, biological and genetic factors have been collected. We have based IRLSA on the ‘Healthy ageing’ framework9,19–26 (Figure 1) to assess a comprehensive range of different biomarkers and lifestyle and socioeconomic factors, as well as health care indicators that we found in previous literature and research. The study is designed to be broadly comparable with existing longitudinal studies of ageing in developed countries.27–29 Schematic framework of the IRanian Longitudinal Study on Ageing including biomarkers and phenotypes of ageing After prior arrangement, a home visit was conducted, and a general questionnaire and the Home Falls and Accidents Screening Tool (HOME FAST), were completed by trained staff. Participants received a study brochure explaining the study objectives and any preparations that may have been needed for the clinic visit. At the first clinic visit, hair and nail samples, anthropometric measurements, body composition results, blood pressure (BP) levels and electrocardiograms (ECG) were collected. A Food Frequency Questionnaire (FFQ), and a general questionnaire including socioeconomic status, physical activity, social support, depression, anxiety, sleep and cognition were also completed. After laboratory results were released, the second clinic visit was conducted. Participants were invited to revisit the clinic for a general practitioner’s (GP) clinical assessment, spirometry, orthostatic BP and mobility tests; smell and taste evaluations were also performed for a subsample. After completing these rounds, they received a referral form to see an optometrist and audiologist to check their vision and hearing. Details of the different assessments in the core and comprehensive data collections are provided in Supplementary Table S1, available as Supplementary data at IJE online. Some laboratory tests, such as thyroid function, HbA1C and vitamin D, and the clinical examination by a GP were replaced with a nurse/midwife summary assessment, and heart, neurological and respiratory examinations were omitted. Spirometry, orthostatic BP and ECG were not included in the core component either. We used the PERSIAN cohort protocol for anthropometric measures and sitting BP, as well as questionnaires on risk factors, reproductive factors, medication/supplement use, laboratory tests and the biobank setup, which has been described in a previous publication.14 In addition, we used the physical activity scale for older adults to measure the level of activities16 and the short form of the Centre for Epidemiologic Studies Depression (CES-D10) scale,30 Hospital Anxiety and Depression Scale-Anxiety (HADS-A),31 Duke social support,32 De Jong Gierveld short scales for emotional and social loneliness,17 Satisfaction With Life Scale (SWLS),33 Pittsburgh questionnaire for sleep Montreal Assessment (MoCA),15 physical limitation and of of Questionnaire short nutrition screening questionnaire (SCREEN of and mobility and (Supplementary Table the and clinical of the study population. A total of 7462 individuals with a age of ± were enrolled in this study. The were aged years and and only had an of women had to than and a of men had The of participants were only of all participants had a healthy body Based on and use, the of diabetes was in in in in in and was in in in of the participants had were The level of physical activity was in men than in women General of the study IRanian Longitudinal Study on Ageing Neyshabur site body Physical Activity Scale for the and cognition status of the study IRanian Longitudinal Study on Ageing Neyshabur site Montreal cognition Centre for Epidemiologic Studies Depression Hospital Anxiety and Depression Scale-Anxiety Pittsburgh in the comprehensive cohort (n = Physical health of the study IRanian Longitudinal Study on Ageing Neyshabur site BP, blood measurements, IRanian Longitudinal Study on Ageing Neyshabur site in the comprehensive cohort (n = This is the first comprehensive longitudinal study of ageing in the Iranian which will into the health and well-being of older The used in the current study were based on the which us to data to our results with other cohort studies of ageing the The pilot study the researchers to assess the feasibility of different aspects of data collections and of the new in our The comprehensive component of the study includes physical and as well as a will to a wide range of research in the a wide range of different were included in this study, which us to explore the of factors for and The of other study sites will us to examine more outcomes because of the sample the to different ethnicities and improve the of the study an important in studies with older adults, we include a assessment of and a clinical psychological assessment, which will us to data on and throughout the study. biological assessments are of this cohort study, with all longitudinal to follow-up is a limitation is a for death or we are a of strategies to participation in the study. the of the for older availability of the principal investigator in case of any for a those with any to care and free GP upon are of the strategies being used in this study. limitation will be a to follow-up because of disabilities such as a or between the study participants and Our to this limitation is to identify a proxy for such upon all participants were asked to two in case of such If was the for not the we would for either a free or a home visit. will be excluded from the follow-up because of cognition or disabilities they choose not to with the study. of were not included in our study, they may have different health and well-being and however, our study will be to data on indicators of individuals up in as well as information about their We will not any participants if they from home to a home they choose not to participate any They will in the study and services will be arranged to follow-up This will allow us to explore the social, economic and health of home All collected data are and at the study research in the Ageing Research Neyshabur University of Medical Iran. A of the is in the of the PERSIAN study, Iran. the completion of data and the data will be for researchers upon their and the approval Data are not and specific for collaboration would be To more than 60 to access the data have been approved by the IRLSA committee at the Neyshabur site of the study. Since more than have been these and six for have been A number of researchers from different are the IRLSA Information on study details and data access forms be found on the study website or or an e-mail to [[email or contact the principal investigator of IRLSA, Nayyereh Aminisani [[email or [[email protected]]. Supplementary data are available at IJE online. for the IRLSA cohort study has been provided by Neyshabur University of Medical The Iranian of Health and Medical has also to the used in the PERSIAN through In addition, the follow-up phase of the study was approved through by Neyshabur University of Medical We our and to the PERSIAN and research of Neyshabur University of Medical all of the and all participants who were in the current All were in of the protocol and of the Research Committee and all of the All and to all of the and have met

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