Back pain from the epidemiological point of view

Summary In the last decades back pain has reached dramatic proportions in industrialized countries. Disorders of the back are nowadays the leading cause of direct and indirect health care costs. Accurate prevalence estimates are needed to serve as a basis for health care evaluations. A review of epidemiologic studies in the general population reveals that back pain has reached a prevalence of 40 % for current pain. 7 to 18 % are “frequently”, “often”, “daily” or “constantly” affected. 75 % of the adult population suffers from back pain during the last year. 80 to 90 % of the adult population in industrialized countries experience back pain ever. Gender specific differences are only present in severe, chronic forms which are more often experienced by women. Back pain has a prevalence maximum at 50 to 64 years. Older persons display lower prevalence estimates. The prevalence maximum in men is one decade earlier than in women. There are several potential explanations for this prevalence pattern that are discussed in the article. Back pain can be classified by location, temporal characteristics, pain intensity and pain history. Currently, for none of these dimensions generally accepted, uniformly employed and validated definitions are available. In most of the industrialized countries back pain is one of the most expensive symptoms. 75–90 % of the direct and indirect health care costs were caused by those 5–10 % of patients who are disabled. As predictors of back pain a history of back pain and job satisfaction play by far a more important role than the extensively studied mechanical factors. For a first episode of back pain the prognosis is favorable. If the pain persist for more than three months the prognosis is unfavorable. After six months of absenteeism because of back pain more than half of the afflicted never return to work. Rarely back pain is present as a single symptom. In more than 80 % back pain is associated with pain in at least one joint. It remains to be studied if back pain may be viewed as an entity or as part of a more complex pain syndrome.      

Effect of different questionnaire formats on reporting of occupational exposures

During an exposure monitoring study, 78 saw maintenance tradesmen were randomly assigned to be interviewed about their exposures using one of two questionnaire formats: open-ended and partly prompted questions about five categories of materials; and detailed prompting about 75 agents. The more open-ended questionnaire elicited fewer exposure responses overall, but more responses about agents not included on the detailed questionnaire. Composite materials and trade name products were more frequently cited as exposures than individual metals or compounds. Validity of responses was ascertained using air measurements (individual metals) or observations of the employees (composite materials). Sums of sensitivities and specificities were very low (near 1.0) for most of the metals for both types of questionnaire. For composite materials, validity improved substantially. Sensitivities with the partly prompted format (0.44–0.85) were always lower than with detailed prompting (0.80–1.00). Specificities were usually, but not always, higher with partial prompting (0.66–0.92) than with detailed prompting (0.18–0.86). Selection of questionnaire format for an epidemiologic study would depend on the likely prevalence of exposure in controls and the effects of trade-offs in sensitivity and specificity.     

Gd-DTPA-enhanced MR in thoracic disc herniations

Summary The Gd-DTPA-enhanced magnetic resonance findings in two patients with herniated thoracic intervertebral discs are reported. The first patient was a 56-year-old woman with a small subligamentous T6-7 disc herniation, slightly lateralized to the right. The second patient was a 51-year-old man with a central and right posterolateral disc herniation, including a large calcified fragment, at the T8-9 level. The nonenhanced MR examination revealed the presence of an extradural mass lesion in both patients, impinging upon the dural sac and compressing and displacing the spinal cord posteriorly. The lesion was slightly hypointense on both T1- and T2-weighted spin echo sequences. Following intravenous injection of Gd-DTPA in a dosage of 0.1 mmol/kg body weight, enhancement of the posterior longitudinal ligament was noted and triangular areas of contrast uptake were seen to occur in the epidural space above and below the herniated disc. At surgery, they were found to correspond to dilated and congested epidural veins.     

Prospective study of phobic anxiety and risk of Parkinson's disease.

Anxiety disorders are common in Parkinson's disease (PD). However, the risk of PD among people with anxiety has not been examined in a prospective cohort study. We examined this relation prospectively within the Health Professionals Follow-Up Study, a cohort of US male health professionals. In 1988, anxiety was assessed using the Crown-Crisp phobic anxiety index in 35,815 men without PD, stroke, or cancer at baseline. There were 189 incident cases of PD during 12 years of follow-up. After adjusting for age, smoking, and caffeine intake, the relative risk of PD among men with the highest level of anxiety (Crown-Crisp index scores of 4 and above) was 1.5 (95% CI = 1.0-2.1; P-trend = 0.01) compared to men with the lowest level of anxiety. This positive association persisted after excluding cases of PD with onset in the first 2 years of follow-up. Use of anxiolytic medication was also associated with an elevated risk of PD (RR= 1.6; 95% CI = 0.9-3.1), but adjusting for this potential confounder did not materially affect the association between anxiety and risk of PD. Our results suggest that anxiety is a risk factor for PD. Whether this association is causal or the result of shared underlying biology remains a question.     

Immunoglobulin G4 antibodies to rat urinary allergens, sensitization and symptomatic allergy in laboratory animal workers

BACKGROUND AND OBJECTIVES: We have previously reported that high rat urinary allergen (RUA) exposure was not associated with increased risk of rat allergy in long-term-exposed laboratory animal (LA) workers. We aimed to assess whether strong allergen-specific IgG4 responses could explain the absence of a dose response in these subjects. We investigated whether IgG4 was associated with allergen exposure and prevalence of sensitization or respiratory symptoms to rats. The longitudinal relation between IgG4 and rat allergy was studied using data obtained during 2 years of follow-up. METHODS: Five hundred and twenty-nine LA workers answered a questionnaire on respiratory symptoms and occupational history and participated in skin prick testing. Blood samples were analysed for specific IgG4 and IgE to RUA. Exposure to RUA was estimated based on personal air samples. The relation between IgG4 and newly occurring sensitization or rat allergy was studied in workers who were not sensitized or did not report respiratory symptoms to rats. RESULTS: IgG4 titres were higher in atopic than in non-atopic subjects, and increased with higher allergen exposure. Titres were highest in subjects who were sensitized and reported respiratory symptoms to rats when compared with those who were not (geometric mean [geometric standard deviation] = 202 [5.7] vs. 8.4 [18.3] AU). The association between IgG4 and sensitization or symptomatic rat allergy was independent of estimated allergen exposure. IgG4 was a strong predictor of newly occurring sensitization and symptomatic rat allergy during follow-up in atopic and rat-sensitized subjects. CONCLUSION: High exposure to RUA is associated with a strong allergen-specific IgG4 antibody response. High anti-RUA IgG4 is a strong predictor of prevalent and incident sensitization and symptomatic rat allergy in atopic and rat-sensitized subjects. IgG4 can therefore not explain the absence of a dose response between allergen exposure and allergy in long-term-exposed workers. We consider anti-RUA IgG4 to be a marker that combines aspects of exposure and susceptibility.     

Learning and retention of movement sequences in Parkinson's disease.

The purpose of this study was to examine motor learning and retention given extensive practice in two fundamentally different movement sequences. One sequence was a memory-driven task (performing a series of whole body positions from memory) and the other a context-driven task (buttoning). Practice took place over 3 weeks, with performance measured weekly; retention was measured weekly for 3 weeks after practice. There were 7 people with Parkinson's disease (PD) and 7 age-matched neurologically healthy people who participated in this study. Both groups improved performance on both tasks with practice, with the majority of the change for the PD group occurring between 1 and 2 weeks of practice. Although those with PD did not necessarily perform as well as age-matched controls, they learned both sequences in a manner similar to age-matched controls, and exhibited retention across the 3-week retention interval. If people with PD are given sufficient practice they can learn and retain both memory-based and context-driven movement sequences as well as age-matched controls. The results provide support for maintaining physical activity and for intervention through movement therapy.     

Diagnostic sonography of the fetal genitourinary tract

Fetal diagnosis has vastly improved over the last decade. Ultrasound has become the imaging modality of choice. As real-time equipment has improved technologically, the ability to deduce subtle abnormalities has greatly increased. The fetal genitourinary tract may be evaluated for renal dysplasias, anomalies, or obstruction. Points of obstruction and, at times, the exact cause of obstruction may be deduced. Abnormalities of the ureter, bladder, urethra, scrotum, or reproductive system can be detected.     

A longitudinal study of age-associated memory impairment

An 8-year longitudinal study of elderly people has provided data concerning age-associated impairment (AAMI). In 1985 a random sample of 146 persons aged 65 years or more, living in their own homes, were assessed using the Guild Memory Test the Mini–Mental State Examination (MMSE) and other ratings. After excluding 21% of the sample because they scored less than 24 on the MMSE, and another 34% who fulfilled other exclusion criteria, some 48% of the remainder (22% of the total sample) clearly fulfilled NIMH criteria for AAMI and a further 36% (16% of the total sample) were recorded as forgetful. The NIMH criteria are appropriate for certain research purposes but not in assessing prevalence of memory disorders. Follow–up interviews were conducted after 2, 4, 6 and 8 years. The mortality rate and development of dementia among those fulfilling criteria for AAMI appeared similar to the other non-demented groups of subjects; the mortality rate of those with MMSE scores below 24 was significantly higher. Guild test results at 2-yearly intervals showed considerable changes; half of those scoring least well who were retested showed improvement.     

Association and linkage with quantitative traits

This paper examines two approaches for the analysis of quantitative traits: (1) association studies and (2) linkage studies. The trait studied was Q1 from simulated Problem 2 data set in Genetic Analysis Workshop 9. Our purpose was to evaluate associations present in the data, to identify nongenetic and genetic predictors of the trait, and to explore the simulated genome for linkage. Through the association study, we found evidence for the primary major gene associated with this trait. The linkage study found evidence of residual genetic effect acting through other traits. Adjustments of Q1 for Q2 and Q3 led to a failure to find significant effects of MG2 and MG3. This supports the suggestion that adjustment for genetically influenced traits for effects of other genetic traits can reduce the power to detect major gene effects. In summary, we detected the major gene directly associated with the trait of interest through association studies. Linkage analysis detected evidence for two other genes associated to a lesser degree with the trait. © 1995 Wiley-Liss, Inc.