Kohorttiaineistosta uutta tietoa tuki- ja liikuntaelinsairauksista

Cohort study uncovers new information on musculoskeletal disorders

It is already known that smoking during pregnancy affects the child's health in many ways. An extensive birth cohort study has shown that a mother who smokes during pregnancy also impacts the child’s experience of musculoskeletal pain as teenager.

The University of Oulu made history in the 1960s. Almost all babies born in northern Finland in 1966 and their mothers went through extensive health examinations, which have been repeated every 10-15 years. A similar birth cohort study was started again for babies born in 1985 - 1986 and their mothers.

This extensive material provides an endless source for researchers. Based on this data, over a thousand scientific articles have been produced, which have been used in the preparation of current care recommendations and applied in medicine in many ways. Such large-scale mass studies are rare even on a global scale, so the material is used by researchers around the world.

A lot of new information has been obtained from this data, including information on eye and skin diseases, diabetes, dentistry, gynaecology and psychological illnesses.

Professor Jaro Karppinen from the University of Oulu has been using birth cohort data in his musculoskeletal disorders research for almost twenty years. In the early 2000s, Karppinen’s research group took a sample of around 2,000 people from the younger cohort, to whom additional questions were asked and about 550 of them underwent lower back MRI scans. This was the start of Oulu Back Study. A little later, about 1,500 people from the older cohort with an average of 47 underwent MRI scans.

“Large population-based MRI studies have not really been done in the past,” said Karppinen. “They have opened up interesting new lines of research.”

Lifestyle is connected to pain

One line of research has mapped factors related to the size of the vertebrae in the spine at various stages of life. The background information to this is that the size of the vertebrae correlates to their strength. The smaller the vertebrae, the more susceptible they are to fractures. For example, cohort data has been able to show that exercise, taking part in sports that include jolting and vibration, and adequate calcium intake are associated with a higher vertebral size and thus better vertebral health, especially in women. In addition, regardless of gender, early growth is important for vertebrae size.

“If a child grows rapidly, it predicts a larger vertebra size.”

“Data on the younger cohort has highlighted, among other things, that mothers smoking during pregnancy is clearly linked to a child’s musculoskeletal pain during adolescence. The finding is probably related to a developmental dysfunction of the foetal brain. When the foetal brain cells do not develop normally, it affects the experience of pain.”

“A person's own smoking also increases the likelihood of back pain,” Karppinen pointed out.

Lifestyle and psychosocial factors affect the experience of pain. At the beginning of 2020, Eveliina Heikkala will debate the subject in her doctoral dissertation. She studies the accumulation of lifestyle factors in 16-year-olds among the younger cohort, including sleep disorders, smoking, physical activity, behavioural disorders and depression.

“The accumulation of risk factors is linked to multi-site pain at the age of 16 to 18 and is also linked to unemployment and even early retirement.”

“We need to invest in 16-year-olds. When you’re dealt bad cards, there is a real risk of exclusion,” Professor Karppinen said.

Incorrect treatment for back disorders

A cohort study on musculoskeletal disorders, led by Professor Jaro Karppinen, has also revealed that abnormal imaging findings can also be found in people who are symptom-free. For practical treatment work, this helps healthcare professionals not to give unnecessarily alarming messages about abnormal, degenerative imaging findings to patients. Findings may be meaningless and in no way associated with patient symptoms.

“A doctor should not tell a patient about an abnormal finding if they are not sure of the significance of the finding. This would reduce patient anxiety. I have seen bad examples where a healthcare professional has exaggerated the significance of degenerative imaging findings to patients, which has resulted in people becoming too careful with their backs. If they had dared to use their backs more and live normally, they would probably have done much better.”

The upcoming artificial intelligence-based interpretation of images is likely to help patients to obtain reliable information from imaging studies in the future. An artificial intelligence-based image analysis can use population-based data and enable a patient to relate their own imaging findings to the findings of those of the same age.

“The abundance of abnormal imaging findings, even on people without symptoms, has also been strongly reflected in the current care recommendations,” Karppinen explained. The problems of imaging findings and the correct interpretation of images has also been introduced in healthcare training.

Next, focus moves to intestinal flora

In the future, University of Oulu's birth cohort data will be used, among other things, in the study of genetic factors of musculoskeletal disorders. Analysis of bacterial flora in the gut may also open new prospects for musculoskeletal disorders research.

“Nutrition is a surprisingly important thing. A lack of variety in nutrition is thought to be a major cause of chronic diseases,” Professor Jaro Karppinen said.

Text: Raija Tuominen

Last updated: 5.8.2019