Research based on national quality registers
There are unique opportunities in Sweden to conduct clinical research. The underlying advantages are the country's civic registration system and the extensive range of valuable registers that are available. There are national quality registers for many groups of patients as well as comprehensive population and health data registers. Health data registers include the Cancer Registry, the Prescribed Drug Register, the Medical Birth Register and the National Patient Register. Data from different registers can be coordinated using civic registration numbers. Research using register data and coordinated processing of data from several registers may only be carried out following approval by an ethics committee, which examines the researchers' expertise and the scientific foundation of the project.
Quality register studies sometimes the only way
The gold standard in medical research is the randomised controlled study although the value of such studies could be constrained by limited selection, insufficient follow-up time and overly strict patient selection.
Research based on data from national quality registers have several advantages compared to randomised controlled studies. Some things can only be studied with the aid of quality registers. Several national quality registers include virtually all patients within a specific group. Data could have been collected over many decades. A large patient base monitored over a long period allows unusual phenomena, such as rare side effects, complications or comorbidity, to be analysed with great statistical power. In surgery it is difficult to compile a sufficiently large number of cases in randomised studies in order to draw accurate conclusions but this is made possible with the aid of national quality registers.
Sometimes randomised controlled studies cannot be conducted for ethical reasons. It is not possible, for example, to draw lots to decide which patients with cardiac arrest receive defibrillation after one minute and which receive defibrillation after two minutes. It is possible, however, to use a quality register to compare outcomes for patients who received defibrillation at different times.
Patient base reflects clinical reality
The fact that the patient base in quality register studies has not undergone a strict selection procedure has both benefits and drawbacks. The main benefit is that the group reflects clinical reality. Cases can vary in severity and difficulty. Patients are young and old and have every conceivable type of background and comorbidity. Some have been operated on by the most skilled surgeons and some by the less experienced. Some had the most ambitious care teams on hand whilst other teams were perhaps not quite as motivated. This allows conclusions to be drawn about how different treatments work in the regular care system and not just for a narrowly selected group of patients at a university hospital.
Confounders can distort results
A disadvantage of having patients in quality register studies who have not been subjected to a strict selection procedure is that the results could be distorted by various confounders. A certain form of treatment might appear to have produced poor results but this could be because the patients who received the treatment were the oldest and the most seriously ill. Highly detailed information about the patients in the register frequently allows corrections to be made for confounders.
A fraction of the cost compared with randomised studies
Quality register studies are far less costly than randomised controlled studies. The cost of a survey involving tens of thousands of patients could run into hundreds of millions crowns if it were conducted as a randomised controlled study. A quality register study could cost just a few million. The reason is that national quality registers exist primarily to improve care and they are built up within the normal system. Data already exists and the extra cost to use it for research is minimal. This makes it possible, for example, to study medicines that are off-patent – studies which the pharmaceutical companies are not prepared to fund.
High-quality, low-budget research
There is the potential to combine the cost benefits of quality register studies with the stringency of randomised controlled studies. This is done through what is termed RRCT, register-based randomized controlled trials, where patients in a quality register are selected and then randomly allocated in different groups in a controlled study. Centre of Registers Västra Götaland provides IT support for conducting RRCT.