Body Mass Index Trajectories From Birth to Midlife and Vertebral Dimensions in Midlife: the Northern Finland Birth Cohort 1966 Study

Prediction of lumbar disc herniation resorption in symptomatic patients: a prospective, multi-imaging and clinical phenotype study

BACKGROUND CONTEXT

Symptomatic lumbar disc herniations (LDH) are very common. LDH resorption may occur by a "self-healing" process, however this phenomenon remains poorly understood. By most guidelines, if LDH remains symptomatic after 3 months and conservative management fails, surgical intervention may be an option.

PURPOSE

The following prospective study aimed to identify determinants that may predict early versus late LDH resorption.

STUDY DESIGN/SETTING

Prospective study with patients recruited at a single center.

PATIENT SAMPLE

Ninety-three consecutive patients diagnosed with acute symptomatic LDH were included in this study (n=23 early resorption and n=67 late resorption groups) with a mean age of 48.7±11.9 years.

OUTCOMES MEASURE

Baseline assessment of patient demographics (eg, smoking status, height, weight, etc.), herniation characteristics (eg, the initial level of herniation, the direction of herniation, prevalence of multiple herniations, etc.) and MRI phenotypes (eg, Modic changes, end plate abnormalities, disc degeneration, vertebral body dimensions, etc.) were collected for further analysis. Lumbar MRIs were performed approximately every 3 months for 1 year from time of enrollment to assess disc integrity.

METHODS

All patients were managed similarly. LDH resorption was classified as early (<3 months) or late (>3 months). A prediction model of pretreatment factors was constructed.

RESULTS

No significant differences were noted between groups at any time-point (p>.05). Patients in the early resorption group experienced greater percent reduction of disc herniation between MRI-0-MRI-1 (p=.043), reduction of herniation size for total study duration (p=.007), and percent resorption per day compared to the late resorption group (p<.001). Based on multivariate modeling, greater L4 posterior vertebral height (coeff:14.58), greater sacral slope (coeff:0.12), and greater herniated volume (coeff:0.013) at baseline were found to be most predictive of early resorption (p<.05).

CONCLUSIONS

This is the first comprehensive imaging and clinical phenotypic prospective study, to our knowledge, that has identified distinct determinants for early LDH resorption. Early resorption can occur in 24.7% of LDH patients. We developed a prediction model for early resorption which demonstrated great overall performance according to pretreatment measures of herniation size, L4 posterior body height, and sacral slope. A risk profile is proposed which may aid clinical decision-making and managing patient expectations.

The Role of Vertebral Morphometry in the Pathogenesis of Degenerative Lumbar Spinal Stenosis

The aim of the current study was to establish whether the vertebral morphometry (e.g., vertebral body width and spinal canal diameters) is associated with degenerative lumbar spinal stenosis (DLSS). A retrospective computerized tomography (CT) study from L1 to L5 for two sample populations was used. The first included 165 participants with symptomatic DLSS (sex ratio 80 M/85F), and the second had 180 individuals from the general population (sex ratio: 90 M/90F). Vertebral body length (VL) and width (VW) were significantly greater in the stenosis males and females compared to their counterparts in the control. The mean VL in the stenosis males was 31.3 mm at L1, 32.6 mm at L2, 34 mm at L3, 34.1 mm at L4, and 34.5 at L5 compared to 29.9 mm, 31.3 mm, 32.6 mm, 32.8 mm, and 32.9, respectively, in the control group (P ≤ 0.003). Additionally, the bony anterior-posterior (AP) canal diameters and cross-sectional area (CSA) were significantly smaller in the stenosis group compared to the control. The mean AP canal values in the stenosis males were 17.8 mm at L1, 16.6 mm at L2, 15.4 mm at L3, 15.6 mm at L4, and 16.1 at L5 compared to 18.7, 17.8, 16.9, 17.6, and 18.8, respectively, in the control group. Vertebral length (OR-1.273 to 1.473; P ≤ 0.002), AP canal diameter (OR-0.474 to 0.664; P ≤ 0.007), and laminar inclination (OR-0.901 to 0.856; P ≤ 0.025) were significantly associated with DLSS. Our study revealed that vertebral morphometry has a role in DLSS development.

Association Between Modic Changes and Low Back Pain in Middle Age: A Northern Finland Birth Cohort Study

STUDY DESIGN

A cross-sectional study of the Northern Finland Birth Cohort 1966 (NFBC1966).

OBJECTIVE

The aim of this study was to evaluate the association between the type, size, and location of lumbar Modic changes (MC), and prolonged disabling low back pain (LBP).

SUMMARY OF BACKGROUND DATA

LBP is the leading cause of disability worldwide and it affects all age- and socioeconomical groups. Only a small proportion of LBP patients are diagnosed with a specific cause: In most cases no single nociceptive cause for the pain can be identified. MC are visualized in magnetic resonance imaging (MRI) as a signal intensity change in vertebral bone marrow and have been proposed to represent a specific degenerative imaging phenotype associated with LBP. MC can be classified into several subtypes, of which inflammatory Type 1 (MC1) is suggested as being more likely to be associated with LBP.

METHODS

We assessed lumbar MRI (n = 1512) for the presence, type, and size of MC. The associations of MC characteristics with prolonged (≥30 days during the past year) and disabling (bothersomeness of LBP at least 6 on a 0-10 Numeric Rating Scale) LBP, evaluated at the time of imaging at 47 years, were analyzed using binary logistic regression, adjusted for sex, BMI, smoking, educational status, lumbar disc degeneration, and disc herniations.

RESULTS

Any MC and MC1 were associated with prolonged disabling LBP (odds ratio [OR] after full adjustments 1.50 [95% confidence interval, CI 1.05-2.15] and 1.50 [95% CI 1.10-2.05], respectively). Furthermore, MC covering the whole anterior-posterior direction or the whole endplate, as well as the height of MC, were significantly associated with prolonged disabling LBP (OR after full adjustments 1.59 [95% CI 1.14-2.20], 1.67 [95% CI 1.13-2.46] and 1.26 [95% CI 1.13-1.42], respectively).

CONCLUSION

Our study showed a significant and independent association between MC and clinically relevant LBP.

LEVEL OF EVIDENCE

3.

Lifelong smoking trajectories of Northern Finns are characterized by sociodemographic and lifestyle differences in a 46-year follow-up

Smoking remains among the leading causes of mortality worldwide. Obtaining a comprehensive understanding of a population’s smoking behaviour is essential for tobacco control. Here, we aim to characterize lifelong smoking patterns and explore underlying sociodemographic and lifestyle factors in a population-based birth cohort population followed up for 46 years. Our analysis is based on 5797 individuals from the Northern Finland Birth Cohort 1966 who self-reported their tobacco smoking behaviour at the ages of 14, 31 and 46. Data on sex, education, employment, body mass index, physical activity, alcohol consumption, and substance addiction were also collected at the follow-ups. We profile each individual’s annual smoking history from the age of 5 to 47, and conduct a latent class trajectory analysis on the data. We then characterize the identified smoking trajectory classes in terms of the background variables, and compare the heaviest smokers with other classes in order to reveal specific predictors of non-smoking and discontinued smoking. Six smoking trajectories are identified in our sample: never-smokers (class size 41.0%), youth smokers (12.6%), young adult quitters (10.8%), late adult quitters (10.5%), late starters (4.3%), and lifetime smokers (20.7%). Smoking is generally associated with male sex, lower socioeconomic status and unhealthier lifestyle. Multivariable between-class comparisons identify unemployment (odds ratio [OR] 1.28–1.45) and physical inactivity (OR 1.20–1.52) as significant predictors of lifetime smoking relative to any other class. Female sex increases the odds of never-smoking and youth smoking (OR 1.29–1.33), and male sex increases the odds of adult quitting (OR 1.30–1.41), relative to lifetime smoking. We expect future initiatives to benefit from our data by exploiting the identified predictors as direct targets of intervention, or as a means of identifying individuals who may benefit from such interventions.

Group‐based trajectory modeling of body mass index and body size over the life course: A scoping review

Background

Group‐based trajectory modeling has been applied to identify distinct trajectories of growth across the life course. Objectives of this study were to describe the methodological approaches for group‐based modeling of growth across the life course and to summarize outcomes across studies.

Methods

A scoping review with a systematic search of Medline, EMBASE, CINAL, and Web of Science was conducted. Studies that used a group‐based procedure to identify trajectories on any statistical software were included. Data were extracted on trajectory methodology, measures of growth, and association with outcomes.

Results

A total of 59 studies were included, and most were published from 2013 to 2020. Body mass index was the most common measure of growth (n = 43). The median number of identified trajectories was 4 (range: 2–9). PROC TRAJ in SAS was used by 33 studies, other procedures used include TRAJ in STATA, lcmm in R, and Mplus. Most studies evaluated associations between growth trajectories and chronic disease outcomes (n = 22).

Conclusions

Group‐based trajectory modeling of growth in adults is emerging in epidemiologic research, with four distinct trajectories observed somewhat consistently from all studies. Understanding life course growth trajectories may provide further insight for population health interventions.

Baseline anthropometric indices predict change in vertebral size in early adulthood - A 10-year follow-up MRI study

The vertebral cross-sectional area (CSA) has an independent effect on vertebral strength. Recent evidence has shown that vertebral dimensions significantly increase in the third decade of life, and that lifestyle factors such as body size and composition are clearly associated with vertebral CSA. This study aimed to test the hypothesis that general anthropometric traits (stature, total body mass, lean body mass, fat mass, body mass index, waist circumference), each objectively measured at baseline, predict the change in vertebral CSA over the subsequent decade. A representative sample of young Northern Finnish adults was used (n = 371) with repeated magnetic resonance imaging (MRI) scans from ~20 and ~30 years (baseline and follow-up, respectively). Vertebral CSA was measured from the MRI scans with high reliability and low measurement error. The statistical analysis was performed using linear regression models adjusted for sex and exact length of MRI interval. According to the regression models, in descending order of effect size, lean body mass (standardized beta coefficient 0.243 [95% confidence interval 0.065-0.420]), total body mass (0.158 [0.043-0.273]), body mass index (0.125 [0.026-0.224]), waist circumference (0.119 [0.010-0.228]), and fat mass (0.104 [0.004-0.205]) were positively and significantly associated with CSA gain over the follow-up, whereas stature (0.079 [-0.066-0.224]) was not associated with CSA change. The results of this study suggest that anthropometric indices may be used for estimating subsequent change in vertebral size. In particular, greater lean body mass seems to be beneficial for vertebral size and thus potentially also for vertebral strength. Future studies should aim to replicate these associations in a dataset with longitudinal anthropometric trajectories and identify the potential common factors that influence both anthropometric traits and vertebral CSA gain.

Eating Behavior Traits, Weight Loss Attempts, and Vertebral Dimensions Among the General Northern Finnish Population

STUDY DESIGN

A population-based birth cohort study.

OBJECTIVE

To evaluate the associations of eating behavior traits and weight loss attempts with vertebral size among the general Northern Finnish population.

SUMMARY OF BACKGROUND DATA

Vertebral fragility fractures are a typical manifestation of osteoporosis, and small vertebral dimensions are a well-established risk factor for vertebral fracturing. Previous studies have associated cognitive eating restraint and diet-induced weight loss with deteriorated bone quality at various skeletal sites, but data on vertebral geometry are lacking.

METHODS

This study of 1338 middle-aged Northern Finns evaluated the associations of eating behavior traits (flexible and rigid cognitive restraint of eating, uncontrolled eating, emotional eating; assessed by the Three-Factor Eating Questionnaire-18) and weight loss attempts (assessed by a separate questionnaire item) with magnetic resonance imaging-derived vertebral cross-sectional area (CSA). Sex-stratified linear regression models were used to analyze the data, taking body mass index, leisure-time physical activity, general diet, smoking, and socioeconomic status as potential confounders.

RESULTS

Women with rigid or rigid-and-flexible cognitive eating restraints had 3.2% to 3.4% smaller vertebral CSA than those with no cognitive restraint (P ≤ 0.05). Similarly, the women who reported multiple weight loss attempts in adulthood and midlife had 3.5% smaller vertebral size than those who did not (P = 0.03). Other consistent findings were not obtained from either sex.

CONCLUSION

Rigid cognitive eating restraint and multiple weight loss attempts predict small vertebral size and thus decreased spinal health among middle-aged women, but not among men. Future longitudinal studies should confirm these findings.

LEVEL OF EVIDENCE

3.

Dairy- and supplement-based calcium intake in adulthood and vertebral dimensions in midlife-the Northern Finland Birth Cohort 1966 Study

Among a representative sample of 1064 Northern Finns, we studied the association of dairy- and supplement-based calcium intake in adulthood with vertebral size in midlife. Inadequate calcium intake (< 800 mg/day) from age 31 to 46 predicted small vertebral size and thus decreased spinal resilience among women but not men.

INTRODUCTION

Small vertebral size predisposes individuals to fractures, which are common among aging populations. Although previous studies have associated calcium (Ca) intake with enhanced bone geometry in the appendicular skeleton, few reports have addressed the axial skeleton or the vertebrae in particular. We aimed to investigate the association of dairy- and supplement-based Ca intake in adulthood with vertebral cross-sectional area (CSA) in midlife.

METHODS

A sample of 1064 individuals from the Northern Finland Birth Cohort 1966 had undergone lumbar magnetic resonance imaging at the age of 46, and provided self-reported data on diet and Ca intake (dairy consumption and use of Ca supplements) at the ages of 31 and 46. We assessed the association between Ca intake (both continuous and categorized according to local recommended daily intake) and vertebral CSA, using generalized estimating equation and linear regression models with adjustments for body mass index, diet, vitamin D intake, education, leisure-time physical activity, and smoking.

RESULTS

Women with inadequate Ca intake (< 800 mg/day) over the follow-up had 3.8% smaller midlife vertebral CSA than women with adequate Ca intake (p = 0.009). Ca intake among men showed no association with vertebral CSA.

CONCLUSIONS

Inadequate Ca intake (< 800 mg/day) from the age of 31 to 46 predicts small vertebral size and thus decreased spinal resilience among middle-aged women. Future studies should confirm these findings and investigate the factors underlying the association of low Ca intake in women but not in men with smaller vertebral size.

The Association of Body Size, Shape and Composition with Vertebral Size in Midlife - The Northern Finland Birth Cohort 1966 Study

Small vertebral size increases the risk of osteoporotic vertebral fractures. Obese individuals have larger vertebral size and potentially lower fracture risk than lean individuals, but scarce data exist on the association between vertebral size and anthropometric measures beyond height, weight, and body mass index (BMI). Here, we evaluated several anthropometric measures (height, weight, BMI, waist circumference, hip circumference, waist-to-hip ratio [WHR], waist-to-height ratio [WHtR], fat mass [FM], lean body mass [LBM], percentage FM [%FM], percentage LBM [%LBM]) as predictors of vertebral cross-sectional area (CSA). We used a representative sample from the Northern Finland Birth Cohort 1966 (n = 1087), with anthropometric measurements from the ages of 31 and 46, bioimpedance analysis from the age of 46, and lumbar magnetic resonance imaging from the age of 46 years. In our data, height and LBM correlated most strongly with vertebral CSA among both sexes (0.469 ≤ r ≤ 0.514), while WHR, WHtR, %FM, and %LBM had the weakest correlations with vertebral CSA (|r| ≤ 0.114). We conclude that height and LBM have the highest, yet only moderate correlations with vertebral size. High absolute LBM, rather than FM or abdominal mass accumulation, correlates with large vertebral size and thus potentially also with lower osteoporotic vertebral fracture risk.

Estimation of stature from dimensions of the fourth lumbar vertebra in contemporary middle-aged Finns

BACKGROUND

Accurate stature estimation plays an essential role in the identification of unknown deceased individuals. For cases in which conventional methods of stature estimation are not applicable, we studied the stature estimation potential of the fourth lumbar vertebra (L4) among a large living sample of representative contemporary Finns. We also generated stature estimation equations for the middle-aged Finnish population.

MATERIAL AND METHODS

Our study population comprised the Northern Finland Birth Cohort 1966 for which lumbar magnetic resonance imaging (MRI) scans and objective measurements of stature were available from midlife (n=1358). After screening the MRI scans for vertebral pathologies, we measured the maximum and minimum widths, depths and heights of the L4 body with high precision and reliability. We then calculated their sums and means together with approximations of vertebral cross-sectional area and volume. By constructing simple and multiple linear regression models around the L4 parameters, we generated equations for stature prediction, and investigated their accuracy on the basis of the adjusted R squared (R²) and standard error of the estimate (SEE) values of the models.

RESULTS

The multiple linear regression models of the mean width, depth and height of L4 yielded the highest prediction accuracies with the lowest prediction errors (for the entire sample, R²=0.621 and SEE=5.635cm; for men, R²=0.306 and SEE=5.125cm; for women, R²=0.367 and SEE=4.640cm).

CONCLUSION

When conventional methods for estimating stature are not applicable, the lumbar vertebrae may be utilized for this purpose. Relatively accurate stature estimates can be given on the basis of only L4 dimensions.