Preoperative optimization of modifiable risk factors is associated with decreased superficial surgical site infections after total joint arthroplasty: a prospective case-control study.

BACKGROUND AND PURPOSE: The aim of our study was to investigate change in modifiable risk factors following preoperative optimization and whether risk of superficial surgical site infection (SSI) after total joint arthroplasty (TJA) could be reduced. METHODS: This is a prospective study of implementation of a preoperative optimization pathway for patients waiting for primary TJA. Information regarding the intervention arm was collected from January 2019 to January 2021, first at decision for operation and then at preoperative assessment 1 week prior to operation. The control arm was included between August 2018 and September 2020 after receiving conventional preoperative preparation and information gathered at preoperative assessment. Follow up occurred 6 weeks postoperatively for both groups. The primary outcome was postoperative superficial SSI. RESULTS: The optimization effort resulted in improvement of weight, anemia, HbA1c, vitamin D, and patient engagement. At preoperative assessment the baseline characteristics of the 2 groups were similar except that the intervention group had substantially more comorbidities. Regarding superficial SSI, association was found with BMI ≥ 30 and HbA1c ≥ 42 mmol/mol in the control group but not in the intervention group. When corrected for differences in ASA classification (reflecting comorbidities), age, and sex, being in the intervention group was associated with lower odds of occurrence of superficial SSI compared with the control group (OR 0.64, 95% confidence interval 0.42-0.97). CONCLUSION: We showed that preoperative optimization in a structured cooperation between hospital and primary care was associated with a reduced risk of superficial SSI.

Prevalence of modifiable risk factors in primary elective arthroplasty and their association with infections.

BACKGROUND AND PURPOSE: The aim of this study was to identify the prevalence of modifiable risk factors of surgical site infections (SSI) in patients undergoing primary elective total joint arthroplasty (TJA) receiving conventional preoperative preparation, and to explore their association with infectious outcomes. PATIENTS AND METHODS: Information regarding modifiable risk factors (anemia, diabetes, obesity, nutritional status, smoking, physical activity) was prospectively gathered in patients undergoing primary TJA of hip or knee in 2018-2020 at a single institution with 6 weeks' follow-up time. RESULTS: 738 patients (median age 68 years [IQR 61-73], women 57%) underwent TJA (knee 64%, hip 36%). Anemia was detected in 8%, diabetes was present in 9%, an additional 2% had undiagnosed diabetes (HbA1c > 47 mmol/mol), and 8% dysglycemia (HbA1c 42-47 mmol/mol). Obesity (BMI ≥ 30) was observed in 52%. Serum albumin, total lymphocyte count, and vitamin D below normal limits was identified in 0.1%, 18%, and 16%, respectively. Current smokers were 7%. Surgical site complications occurred in 116 (16%), superficial SSI in 57 (8%), progressing to periprosthetic joint infection in 7 cases. Univariate analysis identified higher odds of superficial SSI for BMI ≥ 30 (OR 2.1, 95%CI 1.2-3.8) and HbA1c ≥ 42 mmol/mol (OR 2.2, CI 1.1-4.2), but no association was found with other factors. CONCLUSION: In a general population undergoing primary TJA an association was found between obesity (52%) and dysglycemia/diabetes (19%) and superficial SSI (8%), which progressed to PJI in 12% of cases, generating a 1% total rate of PJI. Modification of these risk factors might mitigate infectious adverse outcomes.

[Migraine prevalence, migraine incidence and migraine drug prescriptions in primary care in the capital region of Iceland].

INTRODUCTION: The study aim was to describe migraine incidence over the ten-year periods, 2000-2009 and 2010-2019, in individuals aged 10-79 years in primary healthcare centre (PHCC) Sólvangur and Fjörður, Hafnarfirði. Another aim was to estimate migraine prevalence in primary care clinics in the capital area of Iceland over the period 2010-2019 and describe prescriptions for migraine specific drugs and other drugs used for migraine. MATERIAL AND METHODS: This is a retrospective study based on data from medical records from the primary care clinics of the capital region of Iceland. The cohort consisted of individuals aged 10-79 years who were diagnosed with migraine, G43 according to the ICD-10 classification system. RESULTS: Migraine incidence at age 10-79 years over the ten-year period 2000-2009 at the primary care clinic Sólvangur was estimated 3.4 cases per 1000 person-years, during the period 2010-2019 in both Sólvangur and Fjörður clinics migraine incidence was estimated 2.9 cases per 1000 person-years. Increase was shown between the two periods in prescriptions of triptan drugs, opioids, and beta-blockers, where two-thirds of the migraineurs got prescription over the two periods. Women were three times more likely to be diagnosed with migraine than men, but men were diagnosed at younger age than women. Migraine prevalence at age 10-79 years in PHCCs in the capital area of Iceland was 4.4% over the period 2010-2019. CONCLUSION: Migraine prevalence in the PHCCs of the capital area of Iceland was only one third of migraine prevalence in the population-based cohort pilot study Heilsusaga Íslendinga. Increase in opioid drug prescriptions for individuals diagnosed with migraine is of concern and needs further study.

[Psychedelics and treatment of mental disorders: A survey of attitudes and knowledge among psychiatrists, general practitioners and psychologists in Iceland].

INTRODUCTION: Interest in the use of psychedelics has increased following reports of their possible therapeutic potential. However, little is known about the knowledge of and attitudes towards the substances among health care professional who provide treatment for mental disorders in Iceland. An online survey was therefore conducted among members of the Icelandic associations of psychiatrists, general practitioners and psychologists. METHODS: Respondents were 256 in total, including 177 psychologists, 38 psychiatrists and 41 general practitioners that provided information on their background, type of work, knowledge of and attitude towards different types of psychedelic substances and their views on optimal service delivery if psychedelics were approved by licencing authorities and used for treatment. RESULTS: Around half of psychiatrists reported having received questions about treatment with psychedelics in their clinical work, compared to only 14,6% of general practitioners and 17,5% of psychologists. The majority of respondents had little, or no knowledge of the substances targeted in the survey. A majority also expressed negative attitudes towards treatment with psilocybin mushrooms, but was positive towards ongoing scientific research and felt that such a treatment should be prescribed and provided by psychiatrists. Moreover, the majority view was that psilocybin treatment should be provided in specialised clinics or psychiatric units in a hospital setting. Scientific articles on the topic, discussions with colleagues and information in the media were identified as having had most influence on respondents´ attitudes towards psychedelics. Most respondents were interested in further education on psychedelics. CONCLUSIONS: Respondents among these three professions felt that the time has not yet come to use psychedelics in the treatment of mental disorders in Iceland but thought more education on psychedelics, their potential efficacy and adverse health effects is important given the increased interest in psychedelics.

Large-Scale Screening for Monogenic and Clinically Defined Familial Hypercholesterolemia in Iceland.

Objective: Familial hypercholesterolemia (FH) is traditionally defined as a monogenic disease characterized by severely elevated LDL-C (low-density lipoprotein cholesterol) levels. In practice, FH is commonly a clinical diagnosis without confirmation of a causative mutation. In this study, we sought to characterize and compare monogenic and clinically defined FH in a large sample of Icelanders. Approach and Results: We whole-genome sequenced 49 962 Icelanders and imputed the identified variants into an overall sample of 166 281 chip-genotyped Icelanders. We identified 20 FH mutations in LDLR, APOB, and PCSK9 with combined prevalence of 1 in 836. Monogenic FH was associated with severely elevated LDL-C levels and increased risk of premature coronary disease, aortic valve stenosis, and high burden of coronary atherosclerosis. We used a modified version of the Dutch Lipid Clinic Network criteria to screen for the clinical FH phenotype among living adult participants (N=79 058). Clinical FH was found in 2.2% of participants, of whom only 5.2% had monogenic FH. Mutation-negative clinical FH has a strong polygenic basis. Both individuals with monogenic FH and individuals with mutation-negative clinical FH were markedly undertreated with cholesterol-lowering medications and only a minority attained an LDL-C target of <2.6 mmol/L (<100 mg/dL; 11.0% and 24.9%, respectively) or <1.8 mmol/L (<70 mg/dL; 0.0% and 5.2%, respectively), as recommended for primary prevention by European Society of Cardiology/European Atherosclerosis Society cholesterol guidelines. Conclusions: Clinically defined FH is a relatively common phenotype that is explained by monogenic FH in only a minority of cases. Both monogenic and clinical FH confer high cardiovascular risk but are markedly undertreated.

Artificial intelligence in the GPs office: a retrospective study on diagnostic accuracy.

OBJECTIVE: Machine learning (ML) is expected to play an increasing role within primary health care (PHC) in coming years. No peer-reviewed studies exist that evaluate the diagnostic accuracy of ML models compared to general practitioners (GPs). The aim of this study was to evaluate the diagnostic accuracy of an ML classifier on primary headache diagnoses in PHC, compare its performance to GPs, and examine the most impactful signs and symptoms when making a prediction. DESIGN: A retrospective study on diagnostic accuracy, using electronic health records from the database of the Primary Health Care Service of the Capital Area (PHCCA) in Iceland. SETTING: Fifteen primary health care centers of the PHCCA. SUBJECTS: All patients that consulted a physician, from 1 January 2006 to 30 April 2020, and received one of the selected diagnoses. MAIN OUTCOME MEASURES: Sensitivity, Specificity, Positive Predictive Value, Matthews Correlation Coefficient, Receiver Operating Characteristic (ROC) curve, and Area under the ROC curve (AUROC) score for primary headache diagnoses, as well as Shapley Additive Explanations (SHAP) values of the ML classifier. RESULTS: The classifier outperformed the GPs on all metrics except specificity. The SHAP values indicate that the classifier uses the same signs and symptoms (features) as a physician would, when distinguishing between headache diagnoses. CONCLUSION: In a retrospective comparison, the diagnostic accuracy of the ML classifier for primary headache diagnoses is superior to GPs. According to SHAP values, the ML classifier relies on the same signs and symptoms as a physician when making a diagnostic prediction.KeypointsLittle is known about the diagnostic accuracy of machine learning (ML) in the context of primary health care, despite its considerable potential to aid in clinical work. This novel research sheds light on the diagnostic accuracy of ML in a clinical context, as well as the interpretation of its predictions. If the vast potential of ML is to be utilized in primary health care, its performance, safety, and inner workings need to be understood by clinicians.

Prescriptions of antibiotics in out-of-hours primary care setting in Reykjavik capital area.

OBJECTIVE: To describe antibiotic prescriptions in out-of-hour (OOH) service in primary care setting in Iceland and to study the indications for prescriptions. DESIGN: A population based retrospective study, using electronic data from the OOH registration system. SETTING: OOH primary care setting in Reykjavik capital area in Iceland. SUBJECTS: All patients that received a prescription for oral antibiotic drug at an OOH service in Reykjavik capital area over a one-year period. MAIN OUTCOME MEASURES: Number of oral antibiotic prescriptions and diagnosis connected to the prescriptions according to age and sex. RESULTS: There were 75,582 contacts with the OOH primary care of which 25,059 contacts resulted in prescription of an oral antibiotic (33%). The most common antibiotic prescribed in total, and for the diagnosis studied, was amoxicillin with clavulanic acid. It was most often prescribed for acute otitis media. Of those diagnosed with otitis media 50% were treated with amoxicillin with clavulanic acid and 40% of those diagnosed with pneumonia received that treatment. The second most prescribed antibiotic was amoxicillin. Most often it was prescribed for sinusitis, in 47% of cases with that diagnosis. CONCLUSION: Antibiotics are often prescribed in OOH primary care in Iceland and a substantial number of the patients diagnosed in OOH primary care with acute otitis media or pneumonia are prescribed broad-spectrum antibiotics. Key points Antibiotic prescription rate is high and broad-spectrum drugs often prescribed in OOH primary care service in Iceland. The results should encourage general practitioners in Iceland to review antibiotic prescriptions in OOH service.

[Vitamin D status of Icelandic children and youngsters: Longitudinal study]. / D-vítamínbúskapur íslenskra barna og ungmenna. Langtímarannsókn

OBJECTIVE: Vitamin D plays a key role for children's growth and physical developement, not only by promoting bone health but also by its influence on extraskeletal systems. The Icelandic Directorate of Health recommends a vitamin D concentration in blood of at least 50 nmol/l. The object of this study was to evaluate the vitamin D status of Icelandic children and youngsters at four different ages, and furthermore to evaluate changes in vitamin D concentrations over time and connection to parathyroid hormone status (S-PTH). MATERIAL AND METHODS: The subjects were students from six elemen-tary schools in Reykjavík, born in 1999. Blood tests were taken four times, in 2006, 2008, 2015 og 2017. Some of the subjects took part in all four tests, but more students joined in 2015 and 2017. RESULTS: In all the tests, around 60% of the subjects had lower vitamin D concentrations than recommended by The Icelandic Directorate of Health. Only 13% met the recommended criteria of a concentration over 50 nmol/l in repeated tests and 38.9% of the subjects had lower concentrations than recommended in at least two tests. There was no significant difference between sexes except that 17 year old girls had significantly higher Vitamin D concentrations than boys (p=0.04). S-PTH was negatively correlated to vitamin D concentrations at ages 7, 15 and 17 but there was not a significant correlation at age 9. S-PTH values were lowest at age 7 and then increased with age. CONCLUSION: The majority of Icelandic children and youngsters have vitamin D concentrations under the values recommended by The Icelandic Directorate of Health. In many cases, the concentrations are repeatedly too low. It is clear that there is a need for increased vitamin D intake within this group if the goal regarding recommended concentrations is to be achieved. However, the influence of vitamin D deficiency on public health is not fully known.

A rare missense mutation in MYH6 associates with non-syndromic coarctation of the aorta.

Aims: Coarctation of the aorta (CoA) accounts for 4-8% of congenital heart defects (CHDs) and confers substantial morbidity despite treatment. It is increasingly recognized as a highly heritable condition. The aim of the study was to search for sequence variants that affect the risk of CoA. Methods and results: We performed a genome-wide association study of CoA among Icelanders (120 cases and 355 166 controls) based on imputed variants identified through whole-genome sequencing. We found association with a rare (frequency = 0.34%) missense mutation p.Arg721Trp in MYH6 (odds ratio = 44.2, P = 5.0 × 10-22), encoding the alpha-heavy chain subunit of cardiac myosin, an essential sarcomere protein. Approximately 20% of individuals with CoA in Iceland carry this mutation. We show that p.Arg721Trp also associates with other CHDs, in particular bicuspid aortic valve. We have previously reported broad effects of p.Arg721Trp on cardiac electrical function and strong association with sick sinus syndrome and atrial fibrillation. Conclusion: Through a population approach, we found that a rare missense mutation p.Arg721Trp in the sarcomere gene MYH6 has a strong effect on the risk of CoA and explains a substantial fraction of the Icelanders with CoA. This is the first mutation associated with non-familial or sporadic form of CoA at a population level. The p.Arg721Trp in MYH6 causes a cardiac syndrome with highly variable expressivity and emphasizes the importance of sarcomere integrity for cardiac development and function.

Vitamin D status of Icelandic children and its influence on bone accrual.

The importance of vitamin D for children's bone health has been well established, but the effects of less severe deficiency are not fully known. The main objective of this study was to assess the vitamin D status of Icelandic children at the age of 7, and again at 9 years of age, and the association of vitamin D status with bone mineral content and bone accrual over 2 years. We invited 321 children to participate in this study, and 267 (83 %) took part; 211 (79 %) underwent a DXA scan and 164 were again scanned 2 years later; 159 (60 %) vitamin D samples were measured and 119 (75 %) were measured again 2 years later. At age 7, 65 % of the children had vitamin D concentrations <50 nmol/l, and at age 9 this figure was 60 %. At age 7, 43 % of the children had insufficient amounts of vitamin D (37.5-50 nmol/l), and 22 % had a vitamin D deficiency (<37.5 nmol/l). In linear regression analysis, no association was found between vitamin D and bone mineral content. Furthermore, there was no significant difference in bone accrual over 2 years for the children with insufficient or deficient vitamin D at both ages, compared to those having more than 50 nmol/l at both time points. More than 60 % of Icelandic children have inadequate concentrations of vitamin D in serum repeatedly over a 2-year interval. However, vitamin D in the range did not have a significant effect on bone mineral content or accrual at ages 7 and 9.

Multimorbidity and use of hypnotic and anxiolytic drugs: cross-sectional and follow-up study in primary healthcare in Iceland.

BACKGROUND: The prevalence of multimorbidity is increasing worldwide, presumably leading to an increased use of medicines. During the last decades the use of hypnotic and anxiolytic benzodiazepine derivatives and related drugs has increased dramatically. These drugs are frequently prescribed for people with a sleep disorder often merely designated as "insomnia" in the medical records and lacking a clear connection with the roots of the patients' problems. Our aim was to analyse the prevalence of multimorbidity in primary healthcare in Iceland, while concurrently investigating a possible association with the prevalence and incidence of hypnotic/anxiolytic prescriptions, short-term versus chronic use. METHODS: Data were retrieved from a comprehensive database of medical records from primary healthcare in Iceland to find multimorbid patients and prescriptions for hypnotics and anxiolytics, linking diagnoses (ICD-10) and prescriptions (2009-2012) to examine a possible association. Nearly 222,000 patients, 83 % being local residents in the capital area, who contacted 16 healthcare centres served in total by 140 general practitioners, were set as a reference to find the prevalence of multimorbidity as well as the prevalence and incidence of hypnotic/anxiolytic prescriptions. RESULTS: The prevalence of multimorbidity in the primary care population was 35 %, lowest in the young, increasing with age up to the 80+ group where it dropped somewhat. The prevalence of hypnotic/anxiolytic prescriptions was 13.9 %. The incidence rate was 19.4 per 1000 persons per year in 2011, and 85 % of the patients prescribed hypnotics/anxiolytics were multimorbid. Compared to patients without multimorbidity, multimorbid patients were far more likely to be prescribed a hypnotic and/or an anxiolytic, OR = 14.9 (95 % CI = 14.4-15.4). CONCLUSIONS: Patients with multiple chronic conditions are common in the primary care setting, and prevalence and incidence of hypnotic/anxiolytic prescriptions are high. Solely explaining use of these drugs by linear thinking, i.e. that "insomnia" leads to their prescription is probably simplistic, since the majority of patients prescribed these drugs are multimorbid having several chronic conditions which could lead to sleeping problems. However, multimorbidity as such is not an indication for hypnotics, and doctors should be urged to greater caution in their prescribing, bearing in mind non-pharmacological therapy options.

Result of school-based intervention on cardiovascular risk factors.

OBJECTIVE: To assess the effectiveness of a two-year school-based intervention, consisting of integrated and replicable physical activity and nutritional education on weight, fat percentage, cardiovascular risk factors, and blood pressure. DESIGN AND SETTING: Six elementary schools in Reykjavik were randomly assigned to be either intervention (n = 3) or control (n = 3) schools. Seven-year-old children in the second grade in these schools were invited to participate (n = 321); 268 (83%) underwent some or all of the measurements. These 286 children were followed up for two years. INTERVENTION: Children in intervention schools participated in an integrated and replicable physical activity programme, increasing to approximately 60 minutes of physical activity during school in the second year of intervention. Furthermore, they received special information about nutrition, and parents, teachers, and school food service staff were all involved in the intervention. Subjects. 321seven-year-old schoolchildren. MAIN OUTCOME MEASURES: Blood pressure, obesity, percentage of body fat, lipid profile, fasting insulin. RESULTS: Children in the intervention group had a 2.3 mmHg increase in systolic blood pressure (SBP) and a 2.9 mmHg increase in diastolic blood pressure (DBP) over the two-year intervention period, while children in the control group increased SBP by 6.7 mmHg and DPB by 8.4 mmHg. These changes were not statistically significant. Furthermore there were no significant changes in percentage body fat, lipid profile, or fasting insulin between the intervention and control schools. CONCLUSION: A two-year school-based intervention with increased physical activity and healthy diet did not have a significant effect on common cardiovascular risk factors.

Drug use during early pregnancy: cross-sectional analysis from the Childbirth and Health Study in Primary Care in Iceland.

OBJECTIVE: To analyse drug use in early pregnancy with special focus on socio-demographic factors associated with psychotropic and analgesic drug use. DESIGN: Cross-sectional study. SETTING AND SUBJECTS: A total of 1765 women were invited via their local health care centres, and 1111 participated at 11-16 weeks of pregnancy by filling out a postal questionnaire concerning socio-demographic and obstetric background, stressful life events, and drug use. MAIN OUTCOME MEASURES: Drug use prior to and early on in pregnancy, socio-demographic factors, smoking, and adverse life events were investigated. Drug categories screened for were psychotropics (collective term for antidepressants, relaxants, and sleep medication), analgesics, hormones, nicotine, vitamins/minerals, and homeopathic medicine. RESULTS: Drug use from the aforementioned drug categories, excluding vitamins/minerals and homeopathic medicine, was reduced by 18% during early pregnancy, compared with six months prior to conception (49% vs. 60%). Psychotropic drug use during early pregnancy was associated with elementary maternal education (p < 0.5), being unemployed (p < 0.001), being single/divorced/separated (p < 0.01), smoking prior to or during pregnancy (p < 0.01), forced to change job/move house (p < 0.001), and psychotropic drug use six months prior to pregnancy (p < 0.001). No items on the stressful life events scale were associated with increased analgesic use, which increased only with multiparity. CONCLUSIONS: Use of analgesics and psychotropic drugs seems common in pregnancy. Our results indicate that lack of a support network, stressful life events, and lower status in society may predispose women to more drug use. GPs and midwives responsible for maternity care could take this into account when evaluating risk and gain for women and foetuses in the primary care setting.

Smoking during pregnancy: childbirth and health study in primary care in Iceland.

OBJECTIVE: To study the prevalence and possible predictors for smoking during pregnancy in Iceland. DESIGN: A cross-sectional study. SETTING: Twenty-six primary health care centres in Iceland 2009-2010. SUBJECTS. Women attending antenatal care in the 11th-16th week of pregnancy were invited to participate by convenient consecutive manner, stratified according to residency. A total of 1111 women provided data in this first phase of the cohort study. MAIN OUTCOME MEASURES: Smoking habits before and during early pregnancy were assessed with a postal questionnaire, which also included questions about socio-demographic background, physical and emotional well-being, and use of medications. RESULTS: The prevalence of smoking prior to pregnancy was 20% (223/1111). During early pregnancy, it was 5% (53/1111). In comparison with women who stopped smoking during early pregnancy, those who continued to smoke had on average a significantly lower level of education, had smoked more cigarettes per day before pregnancy, and were more likely to use nicotine replacement therapy in addition to smoking during pregnancy. A higher number of cigarettes consumed per day before pregnancy and a lower level of education were the strongest predictors for continued smoking during pregnancy. CONCLUSION: The majority of Icelandic women who smoke stop when they become pregnant, and the prevalence of smoking during pregnancy in Iceland is still about 5%. Our results indicate stronger nicotine dependence in women who do not stop smoking during pregnancy. Awareness of this can help general practitioners (GPs) and others providing antenatal care to approach these women with more insight and empathy, which might theoretically help them to quit.

Fat mass increase in 7-year-old children: more bone area but lower bone mineral density.

The main aims of this study were, to evaluate what effect a change in fat mass (FM) and lean body mass (LBM) has on bone parameters over 2 years' time, in 7-year-old school children and to see what effect fitness had on bone parameters in these children. A repeated-measures design study was conducted where children born in 1999 from six elementary schools in Reykjavik, Iceland were measured twice. All children attending second grade in these six schools were invited to participate. Three hundred twenty-one children were invited, 211 underwent dual-energy X-ray absorptiometry (DXA) scans at the age of seven, and 164 (78 %) of the 211 had DXA scans again 2 years later. Increase in both FM and LBM was associated with increased total body bone mineral content (BMC) and bone area (BA). An increase in FM was more strongly positively associated with BA while an increase in LBM was more strongly associated with an increase in BMC. An increase in FM was negatively associated with change in bone mineral density (BMD), but an increase in LBM was positively associated with change in BMD. Fitness was positively associated with bone parameters when weight, height and sex were accounted for. The present results suggest that an increase in fat mass over 2 years is associated with an increase in BA and BMC, but a decrease in BMD in the whole body. An increase in LBM accrual, on the other hand, is positively associated with all bone parameters in the body. Fitness is associated with both BMC and BMD but not BA.

Physical and cognitive impact following SARS-CoV-2 infection in a large population-based case-control study.

BACKGROUND: Persistent symptoms are common after SARS-CoV-2 infection but correlation with objective measures is unclear. METHODS: We invited all 3098 adults who tested SARS-CoV-2 positive in Iceland before October 2020 to the deCODE Health Study. We compared multiple symptoms and physical measures between 1706 Icelanders with confirmed prior infection (cases) who participated, and 619 contemporary and 13,779 historical controls. Cases participated in the study 5-18 months after infection. RESULTS: Here we report that 41 of 88 symptoms are associated with prior infection, most significantly disturbed smell and taste, memory disturbance, and dyspnea. Measured objectively, cases had poorer smell and taste results, less grip strength, and poorer memory recall. Differences in grip strength and memory recall were small. No other objective measure associated with prior infection including heart rate, blood pressure, postural orthostatic tachycardia, oxygen saturation, exercise tolerance, hearing, and traditional inflammatory, cardiac, liver, and kidney blood biomarkers. There was no evidence of more anxiety or depression among cases. We estimate the prevalence of long Covid to be 7% at a median of 8 months after infection. CONCLUSIONS: We confirm that diverse symptoms are common months after SARS-CoV-2 infection but find few differences between cases and controls in objective parameters measured. These discrepancies between symptoms and physical measures suggest a more complicated contribution to symptoms related to prior infection than is captured with conventional tests. Traditional clinical assessment is not expected to be particularly informative in relating symptoms to a past SARS-CoV-2 infection.

Persistent symptoms are commonly reported after SARS-CoV-2 infection, and this is often described as long Covid. We compared different symptoms reported following SARS-CoV- 2 infection with the results obtained during various medical evaluations that are often used to assess health, such as blood tests, smell tests, taste tests, hearing tests, etc. We compared symptoms and test results between 1,706 Icelanders who had been infected previously with SARS-CoV-2 infection (cases) and 14,398 individuals who had not been infected (controls). Out of 88 assessed symptoms, 41 were more common in cases than controls. However, relatively few differences were seen in the results obtained from the various medical evaluations (cases had poorer smell and taste test results, slightly less grip strength, and slightly poorer memory recall than controls). The differences seen between symptoms and results of medical evaluations suggests that conventional clinical tests may not be informative in relating symptoms to a past SARS-CoV-2 infection.