Health Atlas Radiology - MRI part 1

There was a 5% increase in the national examination rate from 2018 to 2022. The total reimbursements from the government to the service providers for MRI examinations during the same period was increased by 14%. In 2022, the reimbursement was 393 million Norwegian kroner.

There were 40% more outpatient MRI examinations (per 10,000 population) performed on residents in referral area Fonna compared with referral area Førde. If all referral areas had the same rate as the area with the highest rate (1,282 per 10,000 population), then there would have been 81,000 more MRI examinations annually, or 13% higher than observed. This equates to an increase of 49 million kroner in health reimbursements, calculated using the average reimbursement in 2022 at the rate of 610 kroner per examination.

On the other hand, if all referral areas had the same rate as the area with the lowest rate (911 per 10,000 population), then there would have been 118,000 fewer examinations annually, or 19% lower than observed. Annual reimbursement would be reduced by 72 million kroner.

Age and gender

The proportion of the population that received an MRI in an outpatient clinic increased with age. The increase is more pronounced for women than for men. Up to the age of 70, there is a higher percentage of women than men that received MRI. After that the proportion that received MRI is the same for both genders.

An analysis of the age group 45-60 showed that approximately 60% of all outpatient brain MRIs and MRIs of the cervikal spine were performed on women. Women have a higher frequency of headaches and neck pains which might explain the higher frequency of these MRIs.

Historical trend

The trend figure above shows that the monthly number of outpatient MRI during the years 2021-2022 was higher than the prior years. There is an observable effect of the COVID-19 pandemic in 2020 where the number of MRI was lower from March to May. After the summer, the number of MRI returned to the same level as the corresponding period in the years 2018-2019.

A comparison with the National Audit Office's report of imaging examinations in the years 2012–2015 shows that the general usage of the MRI in outpatient clinics has somewhat reduced. The average annual rate was 1,196 per 10,000 population during 2012-2015 compared to 1,126 per 10,000 population during 2018-2022.

Remarks

MRI is an advanced imaging technology that can distinguish different types of tissues and describe the internal organs better than most other types of examinations. It is often an essential and necessary part of the medical investigation or treatment plan. However, an MRI examination may consist of many images and require a lot of resources in the form of access to highly skilled health professionals, time and equipment. There is also a potential risk that patients may be subjected to unnecessary further examination or treatment, based on incidental findings with little clinical importance. Reducing MRI examinations that provide little or no benefits ensures that the valuable resources are freed up for patients who need it most without long wait time.

In this atlas we present the consequences of an increase or decrease in the cost of government reimbursements should the rate in all referral areas across the country be the same, i.e., either equal to the highest or the lowest observed rate. This does not necessarily mean that either of these are the desired level. For many types of MRI examinations, it is difficult to conclude if the observed variation is a sign of over- or underuse without further information such as the reason for the examination, or activities within the healthcare services before and after the examination. Information on the use of healthcare services before and after the examination is available for some of the examinations we have included in the atlas (shoulder, knee, and prostate) but not all. Moreover, it is also a challenge to deduce the reasonable level of usage of the imaging services when we do not have trustworthy information about the referrer (GP, private specialist, or hospital).

Overall, there are small to moderate geographical variations in the usage of MRI examinations in outpatient services in Norway. However, since the total volume of activities is high, the negative consequences such as waste of resources and the unnecessary stress put on the patients are still significant. It is probable that some of the observed variation is due to different medical practices, or differences in the availability of medical equipment or human resources.

Differences in the availability of service from private imaging clinics is the main reason that residents in referral areas Finnmark and Helgeland had the lowest proportion of MRI that was performed in a private clinic. Additionally, referral areas Førde, Nord-Trøndelag, and Møre og Romsdal also have limited access to private clinics. Notably four of these five areas have MRI rate below the national average.

There was an 8% increase in the national rate, from 205 to 220 per 10,000 population, and the increase was mainly in the years 2021 and 2022. Brain MRI was the most frequently performed MRI examination in the period 2018–2022 and accounted for 19% of annual outpatient MRI examinations. Total reimbursement from the government to the service providers in 2022 amounted to 86 million kroner.

50% more brain MRI were carried out per 10,000 population for residents in the referral area Østfold compared to referral area Finnmark. If all referral areas had a rate equal to the highest, 243 per 10,000 population, then 17,100 more examinations would have been carried out nationally, an increase of 15%, over one year. This corresponds to an increase of 12 million kroner in reimbursements, given the average reimbursement of 705 kroner per examination in 2022.

On the other hand, if all referral areas had the lowest rate, 162 per 10,000 population, then 26,000 fewer examinations would be carried out nationally, a reduction of 23%, over one year. Annual reimbursement would have been reduced by 18.4 million kroner.

Age and gender

In total, there were 440,000 unique patients who underwent a brain MRI examination during the five-year study period of 2018-2022. There were almost twice as many women as men, especially in the 15-55 age group. It is likely that part of the explanation is due to headaches and migraines, which occur more frequently in women. Most of the patients (84%) only had one brain MRI in the five-year period. 11% had two, and 5% had three or more brain MRI. There was little variation in the proportion of patients who had multiple examinations between the referral areas.

Historical trend

The trend figure shows that the monthly number of outpatient brain MRI in the years 2021–2022 was higher than in previous years. A pandemic effect is observed in 2020, where the number of brain MRI performed was lower in March to May. After the summer, the number of examinations per month in 2020 was roughly at the same level as the corresponding period in the years 2018–2019.

A comparison with the National Audit Office's report of imaging examinations in the years 2012–2015 shows that the average rate for outpatient brain MRI remains unchanged, and neither has the geographical variation.

Remarks

There was geographical variation in the number of outpatient brain MRI performed across the referral areas. Since the total volume is quite high, even minor variation can be significant.

However, many brain MRIs are also performed on inpatients. As an example, for residents of referral areas within the Northern Norway regional health trust, inpatients accounted for 30% of all brain MRI examinations. This makes it difficult to assess whether the observed variation in the use of outpatient brain MRIs is a result of different medical practices.

Furthermore, there are many different indications for brain MRI. There are professional guidelines that recommend the use of MRI, for example for dementia investigations, where both CT and MRI are mentioned, but MRI is preferred.

In order to assess whether there is overuse or underuse of outpatient brain MRI, more information is needed. SKDE will therefore apply for access to additional data for the activities in the specialist and primary healthcare service before and after a brain MRI and report the findings at a later date.

Residents in the referral areas of Finnmark and Helgeland had the lowest proportion of brain MRI performed in private clinics, followed by the referral areas of Førde, Nord-Trøndelag and Møre and Romsdal. All of these areas have a brain MRI rate lower than the national average.

Shoulder MRI accounted for 10% of annual outpatient MRI examinations in the period, and total reimbursement paid in 2022 amounted to 26.4 million kroner.

There were almost twice as many shoulder MRIs performed per 10,000 population for residents in referral area Østfold than in the referral area Telemark. If all referral areas had a rate equal to the highest, 135 per 10,000 population, then 14,600 more examinations would have been carried out nationally, an increase of 25%, in one year. This corresponds to an increase of 6.5 million kroner in reimbursements, given the average reimbursement of 445 kroner per examination in 2022.

On the other hand, if all referral areas had the lowest rate, 73 per 10,000 population, then 18,600 fewer examinations would be carried out nationally, a reduction of 32%, in the course of one year. Annual reimbursement would have been reduced by 8.3 million kroner.

Age and gender

The proportion of men and women who underwent a shoulder MRI was equal.

Historical trend

The trend figure above shows that the monthly number of outpatient shoulder MRI in the years 2021–2022 was higher than in previous years. A pandemic effect is observed in 2020, where the number of shoulder MRIs performed was lower in March through May. After the summer, the number of examinations per month in 2020 returned to the same level as the corresponding period in the years 2018–2019.

A comparison with the National Audit Office's report of imaging examinations in the years 2012–2015 shows that the use of outpatient MRI of the shoulder has been slightly reduced, from 112 per 10,000 population per year in 2012–2015 to 108 per 10,000 population per year in 2018–2022. Geographical variation is also somewhat reduced. The ratio between the highest and lowest average rate per 10,000 population in referral areas has been reduced from 2.5 in the period 2012–2015 to 1.8 in the period 2018–2022. The five referral areas with the highest rate in the years 2012–2015 have reduced the rate somewhat but are still among the top six in the period 2018–2022. In contrast, the three referral areas with the lowest rate in 2012–2015 have increased the rate in 2018-2022.

Remarks

There was moderate to large geographical variation in the number of MRI examinations of the shoulder in Norway. Furthermore, a large proportion, almost 60%, of the examinations were carried out on patients over 50 years of age. An MRI of the shoulder is often performed as a part of examinations before the surgery. The number of patients with an indication for shoulder operation usually decreases with age, except for osteoarthritis surgery. The large volume of examinations raises the question whether some shoulder MRIs are performed without any treatment consequences.

Residents of Finnmark and Helgeland had the lowest proportion of shoulder MRI that were performed in private imaging clinics, followed by the referral areas of Førde and Nord-Trøndelag. However, there was no clear relationship (correlation analyses) between rates for shoulder MRI and proportions performed at private clinics at the referral area level.

The MRI scans were performed on both sides of the shoulder (bilateral) in 7.5% of the patient visits. There was a slightly larger proportion of bilateral shoulder MRI examinations in private clinics, 8%, versus 5% in public hospital radiology departments. Bilateral examinations were carried out more often (10%) for residents in referral areas Stavanger and Østfold compared to 4% for residents in referral area Finnmark.

Shoulder MRI is sometimes combined with MRI of cervical spine. Such combination is performed more often in private clinics (9% of shoulder MRI) than in public hospital radiology departments (5%).

Nationally, 173 shoulder MRIs per 10,000 population per year were performed on patients over the age of 50. Total reimbursements in 2022 for these patients amounted to 15.8 million kroner.

Degenerative changes increase with age, and the interpretation of abnormalities on MRI images can be difficult because structural changes are common for people without symptoms. Recommendations from the National Professional Guideline for Diagnostic Imaging in Non-traumatic Musculoskeletal Disorders (2014) (LINK!) states that diagnostic imaging is rarely needed in the case of non-traumatic shoulder pain. The guideline does not specify an age limit, but SKDE has chosen to analyze ages 50 years and older as a discretionary assessment since degenerative disorders increase with age.

In the case of chronic shoulder pain, conventional X-rays can detect osteoarthritis. We found that for those over the age of 50 who have had shoulder MRI examinations, 21% had a shoulder X-ray taken within a year prior to the MRI. There was considerable geographical variation. Residents in referral area Finnmark had the highest proportion at 54%, compared to residents in the referral area Fonna at only 14%. The referral areas with the highest proportion of X-rays before MRI are among the referral areas with the lowest proportion of examinations carried out in private clinics. While there was no significant correlation between the rate for shoulder MRI and the proportion performed in private clinics, it is possible that capacity can be a factor in which imaging method is preferred.

The indication for surgical intervention in the shoulder for patients over 50 is limited. Common indications may include repairing a damage to the rotator cuff after conservative treatment or inserting a prosthesis in advanced osteoarthritis. The decision-making forum at the Norwegian institute of Public Health (LINK) recently concluded that in the case of degenerative rotator cuff rupture, non-surgical treatment should be the first choice, as there was little to no effect of surgery compared to conservative treatment.

We found that only a small proportion, 1% (approx. 300), of the shoulder MRI examinations in patients over 50 were followed by the insertion of a shoulder prosthesis or osteotomy within one year. Furthermore, there were 9% (approx. 3,270) where the examination was followed by other surgical intervention in the shoulder within one year. There was large geographical variation and the ratio between the highest and lowest rate was more than 5.

Based on this, it can be interpreted that few of the shoulder MRI in patients over 50 have a clinical and treatment consequence. The examinations without clinical consequences can therefore be considered to have minimal health benefits and represent overdiagnosis.

There was a 17% increase in the national rate, from 36 to 42 per 10,000 population, and the increase was mainly in the years 2021 and 2022. Hand MRI accounted for 3% of annual outpatient MRI examinations in the study period, and total reimbursement paid in 2022 amounted to 10.2 million kroner.

There were twice as many hand MRIs per 10,000 population for residents in referral area Møre og Romsdal compared with referral area Førde. If all referral areas had a rate equal to the highest, 51 per 10,000 population, then 7,200 more examinations would have been carried out nationally, an increase of 35%, in the course of a year. This corresponds to an increase of 3.2 million kroner in reimbursements, based on the average reimbursement of 447 kroner per examination in 2022.

On the other hand, if all referral areas had the lowest rate, 25 per 10,000 population, then 6,700 fewer examinations would be carried out nationally, a reduction of 33%, in the course of a year. The total reimbursement would have been reduced by 3 million kroner annually.

Age and gender

A larger proportion of women than of men underwent an MRI of the hand, and the difference between the genders was greatest in the 50-60 age group.

Historical trend

The trend figure shows that the monthly number of outpatient hand MRI in the years 2021–2022 was higher than in previous years. A pandemic effect is observed in 2020, where the number of hand MRIs performed was lower in March through May. After the summer, the number of examinations per month in 2020 was roughly at the same level as the corresponding period in the years 2018–2019.

A comparison with the National Audit Office's report of imaging examinations in the years 2012–2015 shows that the average rate of outpatient hand MRI has increased by 19%, from 32 per 10,000 population in 2012–2015 to 38 per 10,000 population in 2018–2022. Geographical variation has decreased. The ratio between the highest and lowest average rate per 10,000 population was 2.5 in 2012–2015 and 2.0 in 2018–2022.

Remarks

Compared to the period 2012–2015, the geographical variation in the years 2018–2022 was somewhat reduced, but still considerable. It is also worth noting that in many of the referral areas the rate in the years 2021–2022 was considerably higher than in previous years.

It is likely that the variation is partly due to different medical practices. However, without more information about the indications for the examinations or follow-up and treatment afterwards, it is difficult to assess whether this constitutes unwarranted variation.

Residents in the referral areas of Helgeland, Finnmark and Førde had the lowest proportion of hand MRIs performed by private imaging clinics, followed by residents in Nord-Trøndelag and Møre og Romsdal. However, there is no clear association (correlation analyses) between rates for hand MRI and proportion performed at private clinics at the referral areas level.

An examination of both hands (bilateral) was performed at 9% of the patient visits. There was a greater proportion of these bilateral hand MRI in private clinics, 11% compared to 5% in public hospital radiology departments. For patients in the referral area of Stavanger, it was carried out at 16% of the visit, compared to patients in Nord-Trøndelag where it only applied to 3% of the visits.

13,400 outpatient MRI examinations of the prostate were carried out annually, which corresponds to 88 per 10,000 men between the ages of 35 and 105. Nationally, the number of examinations per 10,000 men was stable in the period 2018–2022, but for certain referral areas, such as Finnmark, Stavanger, Fonna and Helgeland, there was a large variation between the years. Prostate MRI accounted for 2% of annual outpatient MRI examinations in the study period, and the total reimbursements in 2022 amounted to 8.9 million kroner.

More than twice as many prostate MRIs were performed per 10,000 men per year in the referral area Stavanger as in the referral area Førde.

If all referral areas had a rate equal to the area with the highest rate, 131 per 10,000 men, then 6,500 more examinations would have been carried out nationally. This is equivalent to an increase of 47% in a year and corresponds to an increase of 3.9 million kroner in reimbursements paid, given the average reimbursement of 614 kroner per examination in 2022.

If, on the other hand, all referral areas had the same rate as the area with the lowest rate, 58 per 10,000 men, then 6,800 fewer examinations would have been carried out nationally, a reduction of 35% in the course of one year. The annual reimbursements would then have been reduced by 2.9 million kroner.

Age

The MRI examinations of the prostate were carried out primarily on men aged 45-85, and the average and median ages were 67 and 68 years respectively. All referral areas have similar median age.

Historical trend

The trend figure shows that the monthly number of outpatient MRI examinations in the years 2021–2022 was roughly on par with the corresponding month in the previous years. There was a slight pandemic effect in 2020, where the number of MRI examinations was lower in April and May. Starting August, however, the number of examinations per month in 2020 returned to roughly the same level as the corresponding period in the years 2018–2019.

A comparison with the National Audit Office's report of imaging examinations in the years 2013–2015 showed that the number of outpatient MRI examinations of the prostate has increased drastically. During 2013–2015 approximately 8,000 prostate MRIs were performed annually, compared with 13,400 per year during 2018–2022. In other words, the annual number of examinations has increased by almost 70%.

Despite the increase in usage, the geographical variation has been significantly reduced. The ratio between the highest and lowest rate per 10,000 men was 27 in the period 2013–2015, compared with 2.3 in the period 2018–2022.

Remarks

A recently published study (Hofmann et.al. 2022) showed that the number of prostate MRI in Norway more than tripled in the period 2013–2021 while the incidence and mortality of prostate cancer remained unchanged. The largest growth in the number of MRI examinations took place in the years 2013–2014 and 2014–2015, where it increased from approximately 4000 to 7500 and from 7500 to 12000 respectively.

Presumably, a large part of this increase in the number of MRI examinations can be attributed to the introduction of treatment plan (CHECKHER) for cancer in 2015, where MRI of the prostate became a mandatory part of the cancer investigation, even though the increase was observed already before the program was introduced. There has also been a sharp increase in the number of low-risk prostate cancer patients in the period 2010 to 2022 (Hofmann et.al. 2022). This may also be an explanation for the increase in the number of MR prostate examinations from 2013.

Even though the variation has been reduced comparing to the National Audit Office's survey, the volume has increased greatly and the geographical variation in the number of prostate MRI in Norway is therefore considered to be large. The most important indications for prostate MRI are suspicion of prostate cancer and follow-up of prostate cancer. There are geographical differences in the incidence of prostate cancer in Norway (Cancer of Norway 2022), but these are smaller than the geographical differences in the number of MRI examinations.

The referral areas in the western Norwegian regional health authority (Førde, Bergen, Fonna) had the highest proportion, 50% or more, of prostate MRI for their residents carried out at private imaging clinics. In contrast to the referral areas Helgeland, Nord-Trøndelag, Innlandet and Nordland, where just under 2% of the examinations for their residents were carried out at private imaging clinics. There was no correlation between rates for prostate MRI in a referral area and the proportion performed at private imaging clinics.

While suspicion of prostate cancer is the most important indication for performing MRI of the prostate, only 33% of the examinations were performed on patients who were in the care pathway for prostate cancer. This is in accordance with the findings of Hofmann et.al. 2022. There was large geographical variation in the proportion that was in the pathway for prostate cancer. The referral areas Stavanger and Østfold, which had the highest rate for Prostate MRI, had the lowest proportion (17%) of the examinations that were performed on patients in the pathway. In contrast, the highest proportion was around 50% for referral areas Finnmark and Telemark.

Nevertheless, there was no connection (correlation analyses) between rates for prostate MRI and proportion in prostate cancer pathway in the referral areas.

The large differences in the proportion that were in the patient care pathway can be due to several factors. Firstly, not all prostate cancer patients are included in the plan. A study from 2021 (Olsen et.al. 2021) showed that 35% of prostate cancer patients in Norway in the period 2015–2017 were not in a pathway. There were large differences between the referral areas. Secondly, there may be differences in how patients are registered in the pathway, for example whether patients are re-registered into the plan after a negative MRI.

Patients with a cancer diagnosis

Another indication for prostate MRI is cancer diagnosis. A good number of cancer patients will be monitored with prostate MRI during the course of the cancer. About 16% of the MRI examinations were performed on patients with a cancer diagnosis, and the proportion varied from 9% in the referral areas Lovisenberg and Nord-Trøndelag to 28% in the referral area Fonna.

Proportion of patients not in the care pathway or without cancer diagnosis

We have outlined the two most important indications for performing prostate MRI above. Nevertheless, more than half of the MRI examinations of the prostate were performed on patients without these indications. The proportion of MRI examinations for these patients varied widely between the referral areas, from 35% for residents in the Telemark referral area to 67% for residents in the Østfold referral area. Even though there was not a significant relationship (correlation analyses) between the rate for prostate MRI and the proportion without the two indications, it was the referral areas with the highest rate for MRI (Stavanger and Østfold) that also had the highest proportion without indications. This may indicate that MRI of the prostate is performed on a wide range of indication and good capacity in these areas and in turn indicates over usage of prostate MRI in Norway.

PSA tests

Prostate specific antigen, PSA, is produced in the prostate gland and can be detected in the blood with a blood test. In the period 2018–2021, almost 600,000 PSA tests were carried out annually on around 400,000 men in Norway. The number of PSA tests varied significantly between the referral areas, twice as many PSA tests were taken per 10,000 men in the referral area Østfold compared to the referral area Finnmark. Elevated PSA is one of the criteria for justified suspicion of prostate cancer and thus an entry into the treatment pathway for prostate cancer and MRI prostate. Even though there was no significant correlation between the rate of MRI prostate and the rate of PSA tests (correlation analysis) for the referral areas, it is reasonable to assume that extensive use of PSA tests leads to more MRI examinations of the prostate.

Screening of younger men

Prostate cancer is the most common form of cancer for men in Norway. It accounts for 26% of all cancer types in the period 2018–2022 (Cancer in Norway 2022). Half of those diagnosed with prostate cancer in the period 2018–2022 were aged 70 or older. The incidence of prostate cancer increases significantly with increasing age. Men under the age of 60 accounted for approximately 13% of the incidence of prostate cancer in Norway in 2022 (Cancer Register). In our analyses they accounted for 20% of prostate MRI and 30% of PSA tests.

Correlation analyses showed significant relationships between (1) prostate MRI rate and proportion in care pathway, and (2) prostate MRI rate and rate for PSA tests for men aged 60 or younger. Referral areas with a high MRI rate have low proportion in the patient care pathway and high PSA rate. The Choosing Wisely campaign recommends that PSA tests should be performed after the risk assessment during a clinical examination.

Knee MRI accounted for 13% of annual outpatient MRI examinations in the study period, and the total reimbursement paid in 2022 amounted to 33.6 million kroner.

40% more MRI examinations of the knee were carried out per 10,000 population in the referral area Bergen compared with the referral area Finnmark. If all referral areas had a rate equal to the area with the highest rate, 168 per 10,000 population, then 11,000 more examinations would have been carried out nationally. This is equivallent to an increase of 14% in the course of one year, and corresponds to an increase of 4.5 million kroner in reimbursements paid, given the average reimbursement in 2022 of 412 kroner per examination.

If, on the other hand, all referral areas had the lowest rate, 120 per 10,000 population, then 15,000 fewer examinations would have been carried out nationally, a reduction of almost 20%, in the course of one year. Annual reimbursement would have been reduced by 6 million kroner.

Age and gender

The proportion of the population who had an outpatient MRI examination of the knee performed in the period 2018–2022 was relatively equally distributed between the sexes. In the teenage years, 13–19 years, the girls dominated. Among young adults aged 20–40, there was a slightly larger proportion of men, and from the 40s onwards there was a slightly larger proportion of women.

Historical trend

The trend figure shows that the monthly number of outpatient MRI examinations of the knee in the years 2021–2022 was roughly on par with the previous years. A clear pandemic effect is observed in 2020, where the number of MRI examinations performed was lower in March through May. After the summer, the number of examinations per month in 2020 returned to a more similar level as previous years, however, was still slightly below the level in the corresponding period in the years 2018–2019.

A comparison with the National Audit Office's report of imaging examinations in the years 2012–2015 shows that the average rate of outpatient MRI of the knee has been reduced by 15%, from 173 per 10,000 population in 2012–2015 to 147 per 10,000 population in 2018–2022. If we exclude the pandemic year 2020 from the average rate, it would have been 150 per 10,000 population, and thus still constitutes a significant reduction. Geographical variation was reduced. The ratio between the areas with the highest and lowest rate per 10,000 population has been reduced from 1.8 to 1.4. The five referral areas with the highest rate in 2012–2015 have reduced the rate somewhat but are still among the top seven in the period 2018–2022.

Remarks

The Choosing Wisely campaign advises to avoid advanced diagnostic imaging for anterior knee pain unless the patient has hydrops, locking or has tried physical treatment without improvement. There has been a reduction in the use of MRI examinations of the knee since the period 2012–2015. However, there are still almost 50% of the knee MRI examination that are performed on patients over 50.

MRI examination for chronic knee pain usually does not provide information that would change the recommended treatment. The large volume of examinations leads us to assume that many knee MRI are performed without impact on the course of treatment.

Residents in Finnmark and Helgeland had the lowest proportion of knee MRIs performed in private clinics, followed by residents in the referral areas of Førde and Nord-Trøndelag. There may appear to be a moderate relationship (correlation analyses) between rates for knee MRI and proportions performed at private clinics.

11% of knee MRI examinations were performed bilaterally. There was a greater proportion of bilateral examinations carried out at private clinics, 13% compared to 7% at radiology departments in hospitals. There was geographic variation. 15% of the examinations for residents in the referral area Lovisenberg were bilateral examinations compared to 6% for residents in the referral area Nord-Trøndelag.

Degenerative meniscal injuries are most frequently seen in middle-aged and elderly people. It is known that patients over 40 have little or no benefit from surgery for degenerative disorders, and they should be treated conservatively with exercise as best practice. MRI examination for chronic knee pain will most often not provide information that change the recommended treatment, and therefore considered unnecessary. To capture primarily degenerative knee disorders, SKDE has chosen to set a higher discretionary age limit of 50 years.

When investigating knee problems in the middle-aged and elderly patients, an X-ray of the knee should first be carried out, as it is best suited to detect osteoarthritis. If the X-ray does not show definite arthrosis, it may be necessary to take an MRI in some cases. However, this should not be the first choice.

Out of the knee MRI in patients over the age of 50, only 31% had an X-ray of the knee within a year before the MRI. There was considerable geographical variation in this proportion, from 53% for residents in the referral area Nord-Trøndelag to 24% in the referral area of St. Olav. This indicates different treatment practices, where residents in certain referral areas more often start the examination of the knee by receiving an X-ray instead of an MRI, and therefore have a lower utilization rate of knee MRI. The referral areas with the highest proportion of X-rays before MRI are among the ones with the lowest proportion of examinations carried out by private clinics. Although there is no significant correlation between the rate for knee MRI and the proportion done by private clinics, it is possible that capacity is a factor in determining which modality is taken first.

There is rarely indication for knee surgery for patients over the age of 50, except for the indication of osteoarthritis with the insertion of a prosthesis or osteotomy. We found that only a small proportion, 3% (approx. 1,450), of the examinations in patients over 50 were followed by the insertion of a knee prosthesis or an osteotomy performed within one year of knee MRI. Furthermore, there were 5% (approx. 2,200) of the examinations were followed by another surgical intervention on the knee within one year. Based on this, it can be interpreted that few of the investigations have consequence for further treatment. These examinations can therefore be considered to have minimal health benefit and represent overuse.