Wisdom of the aging
Wisdom of the aging
The country is experiencing an unprecedented change in its population; over the next two decades nearly a quarter of us will be over 65. To understand the complex interplay between the physical, social and psychological health of aging Canadians, and how this shift will impact the country’s policies and economy, more than 100 researchers from 26 Canadian universities supported the development of the Canadian Longitudinal Study on Aging. The study sets the bar globally for size and comprehensiveness --- 50,000 men and women will be followed for 20 years. This past summer, the team, which includes co-principal investigators Christina Wolfson of McGill University and Susan Kirkland of Dalhousie University, reached their goal of completing the baseline collection of data on all 50,000 participants. Following this momentous milestone, the CFI talked to the study’s Lead Principal Investigator, Parminder Raina of McMaster University to find out what it takes to pull off a research undertaking of this scale.
You've recruited 50,000 participants who you expect to follow for the next 20 years. Are there other aging studies on that scale?
Nationally no. Internationally, it depends. Out of the studies specifically designed to study aging, there is no comparable initiative that is this size and covers this breadth of information nationally or internationally.
It’s an impressive number: 50,000 people recruited over the course of four years. How did you do it?
We used three sources: Statistics Canada’s Canadian Community Health Survey — Healthy Aging, provincial health registries, and random digit dialing. Around 15 percent of the people we contacted actually took part in the study. We probably contacted around 600,000 people. In places like St. John’s, Newfoundland, we exhausted the sample of eligible people in the age group that we were focusing on, 45 to 85 years old. We wanted 3,000 people from around St. John’s and we contacted everyone in that age group and could only get up to 2,000 eligible individuals. We had to shift our sampling to other parts of Canada to achieve our goal of 50,000.
What were the challenges?
Response rates in Canada have been going down in large population studies so recruitment was more expensive than we thought. We had to pull a lot of resources together to make it happen and be creative in how we dealt with it. Another challenge was coordinating everything, especially in a country like Canada. We had planned to finish recruiting by March 2015, but who knew we were going to have two terrible winters? Some data collection sites were closed for several days because people couldn’t get to them because of snow. We managed. We were delayed only a couple of months. For a large study, I think that’s remarkable.
What was most rewarding about the process of recruiting all of these people?
When we started, it seemed like such a daunting task. But it actually happened as we planned, and within the resources that we were given. After all of the thought that had gone into creating this study, the most rewarding part was to see that it worked as we had planned and the quality of the information was good.
I think it’s a lesson for all of us, that when you propose initiatives like this, there needs to be a reasonable planning period. It’s worth investing a few million dollars in preparing for these large-scale platforms. It pays off in the long term.
How long did you spend planning?
You won’t believe it. We first started working on this idea in 2001. It was ten years before we saw the first dollars for the study to go ahead. It has been fifteen years of my life.
So this is also a personal achievement for you.
It is. And you asked about challenges. Because we have developed this as a platform, I don’t have any special access to the data. Like any other researcher, I have to apply to access it. I struggle with that, as do my other colleagues involved with CLSA, who are very close to this project and who worked very hard for the last ten to fifteen years. We struggle because it impacts our own programs of research, even if it is the right approach.
Would you do anything differently next time around?
I would create a balance between a platform and a program of research for the team. It’s so big and you don’t have time. I don’t get a break from teaching, I still carry out my other programs of research and this study in itself is pretty much a full-time job on top of that. It’s daunting; it sort of takes the fun away.
That impressive number, 50,000, pales in comparison to the amount of data you’ll collect for this long-term study. How will you collect and manage it all?
By design right from the beginning we created major information technology infrastructure to manage these data. We have the Statistics Analysis Centre at McGill University, led by Christina Wolfson, which cleans up, manages and shares data with all of the researchers. We also have a data access committee. Right now we have about 25 applicants who have asked for data to address specific research questions. Those applications were adjudicated by the Data and Sample Access Committee.
Collecting the data is quite interesting. Of 50,000 people, 20,000 are a random sample of the Canadian population. We contact those people every three years by telephone for a one-hour long interview. We developed four computer-assisted call centres: one in Halifax, one in Sherbrooke, Quebec, one in Winnipeg and one in Vancouver. They cover different time zones and languages, and these people are contacted every three years. For the remaining 30,000 — what we call our comprehensive study group — we developed 11 data collection sites across Canada. They’re set up like family physician offices and are equipped with exactly the same equipment all across the country. So if we have a bone density scanner in Hamilton, it’s exactly the same as the one at the other ten sites. All our 10 sites are equipped with a wide variety of equipment such as carotid ultrasounds, ECGs, DEXA, retinal imaging equipment, and audiometers. We take blood and urine samples from all of these people.
For the comprehensive group, we go to their homes, do a one-hour long face-to-face interview, collect lots of information and then set up a time for them to come to a dedicated data collection site. When they come, they are in our data collection site for two and a half hours, and they provide detailed information from bone densities to body composition to calcification in the aorta. We look at carotid arteries. We look at their heart disease issues, blood pressure, and lung function. We do performance testing, unique to aging, where we look at their one-leg balance, and ask them to walk four metres to measure their performance and gait. We do extensive vision testing, including ocular measurements for glaucoma and retinal imaging for the effects of diabetes.
We have other questionnaires mostly focused on disease symptoms and cognitive testing. We also, at each site, developed a phlebotomy lab where blood samples are drawn and processed. This is unique. I don’t know of any other study of this magnitude where blood is drawn, processed and frozen at minus 80 degrees Celsius within one-and-a-half hours.
There is no paper and pencil collection of data. We have developed our own software, so as the measurements are happening the software is pulling the information. The software also has built-in quality checks and tells the operator if something doesn’t make sense. At the coordinating centre in Hamilton, we can see the data come in live. We can see exactly what’s happening on their computer centrally across the country. Once this data is collected, they are sent daily to Hamilton, and then we do a first clean up and then send to Montreal, where the final data samples are prepared. The blood samples from all over the country are shipped weekly to our biobank in Hamilton. Collectively over 20 years we will have around 6 million samples.
Two other impressive numbers: 160 researchers and collaborators, 26 institutions. Can you share your top lessons learned for coordinating this many researchers and institutions?
One big lesson is to be transparent. It’s just how we are as a team, but it has served us well. You also need to pick key people who are team players, as well as excellent scientists. So creating a team environment and trust are the two lessons to run a large consortium like this.
We’ve talked a lot about numbers. Any other big numbers you can wow us with?
It will take 20 years to complete the study. We will do up to 140,000 telephone interviews and up to 210,000 home interviews. We will collect 6 million aliquots of blood and urine, make 300,000 follow-up calls and ask up to 126 million individual questions in the telephone interviews alone. Home visits and visits to the data collection centres will result in up to 174 million data points. At the end of the day, over 20 years, we will have 300 million different data points. Talk about big data, this is big data.
This study is such an impressive undertaking, and on such an important topic. What is your ultimate hope for what it can do?
We want to understand why some people age in a healthy way and why others don’t, and if we understand that, we will be able to inform many policy decisions for which there are no data available as yet. The second part is that this is such a rich resource that it puts Canada on the international map for research in aging. Already we have had a lot of international interest in this dataset. It’s so comprehensive, not just big. It gives people a lot of interesting data to pursue interesting research. I’ve had conversations with people who want to create similar studies in Singapore and Australia. We’re happy to collaborate and share information with them.