Prospective study of tardive dyskinesia in the elderly: rates and risk factors

Estimated incidence rates are presented for three human immunodeficiency virus (HIV)-associated cancers [Kaposi's sarcoma (KS), Burkitt's lymphoma (BL) and other non-Hodgkin's lymphomas (NHLs)] from across the African continent, based on data collected before the HIV epidemic. Mapping of the rates and comparisons with a range of geographical variables indicate completely different distributions for KS and BL but a degree of similarity in the occurrence of Burkitt's lymphoma and other NHLs. Comparisons with rates elsewhere in the world suggest, most notably, that KS was as common in some regions of sub-Saharan Africa as was cancer of the colon in much of Western Europe. Comparison with data from the era of AIDS indicates 20-fold increases in the occurrence of Kaposi's sarcoma in Uganda and Zimbabwe. The highest rates for BL were three to four times the rates for leukaemia at young ages in Western populations, but the general incidence of other NHL was no higher than in the West and very low rates were indicated for much of southern Africa.     

Comparable studies of the incidence of stroke and its pathological types: results from an international collaboration. International Stroke Incidence Collaboration

BACKGROUND AND PURPOSE: Comparing stroke rates in different parts of the world may increase our understanding of both etiology and prevention. However, comparisons are meaningful only if studies use standard definitions and methods, with comparably presented data. We compared the incidence of stroke and its pathological types (cerebral infarction, primary intracerebral hemorrhage, and subarachnoid hemorrhage) in recent studies from around the world. METHODS: Studies with a midyear of 1984 or later, fulfilling standard criteria for a comparable, community-based study, provided original data for comparative analyses. RESULTS: By mid-1995, data were available from 11 studies in Europe, Russia, Australasia, and the United States, comprising approximately 3.5 million person-years and 5575 incident strokes. Age- and sex-standardized annual incidence rates for subjects aged 45 to 84 years were similar (between approximately 300/100,000) and 500/100,000) in most places but were significantly lower in Dijon, France (238/100,000), and higher in Novosibirsk, Russia (627/100,000). In subjects aged 75 to 84 years, however, Novosibirsk no longer ranked higher than the other studies. The distribution of pathological types, when these were reliably distinguished, did not differ significantly between studies. CONCLUSIONS: The similarities in stroke incidence and pathological types are perhaps not surprising given that all the populations were westernized and mainly white. The higher rates in Novosibirsk, disappearing in the elderly, and the lower rates in Dijon have several potential explanations. These include methodological artifact and different patterns of population risk factors. Further work is needed to explore these possibilities and to extend our knowledge of stroke incidence to other parts of the world, especially developing countries.     

Playing-related musculoskeletal disorders in musicians: a systematic review of incidence and prevalence

BACKGROUND: Work-related musculoskeletal disorders cause pain, disability and loss of employment for many workers, including musicians. Although performing arts medicine is a growing field, the health problems of musicians remain under-recognized and under-researched. Therefore, the author undertook a systematic review of published information on the incidence and prevalence of playing-related musculoskeletal disorders (PRMDs) in classical musicians. METHODS: Seven databases were searched for the period 1980 to 1996. The main textbook and performing arts medicine journals were searched manually, as were reference lists of all relevant papers. The author also contacted individuals familiar with the literature of performing arts medicine. Studies were included for review if they reported PRMD incidence or prevalence in classical musicians. Of the 24 studies identified, 18 cross-sectional surveys and cohort studies were reviewed. The author subjectively assessed the studies using criteria modified from an existing evaluation scale and used 4 criteria for data combination. On the basis of prevalence values from the eligible studies, chi 2 tests for heterogeneity were performed. RESULTS: Only one study estimated PRMD incidence. Ten of the 17 prevalence studies were ineligible for data combination, because of low response rates and other methodological problems. In the 7 eligible studies, PRMD point prevalence ranged from 39% to 87% in adult musicians and from 34% to 62% in secondary school music students. The best estimates of PRMD prevalence were derived from the 3 studies that excluded mild complaints; these studies indicated that PRMD prevalence was 39% and 47% in adults and 17% in secondary school music students respectively. Statistical combination of data across studies within each demographic category was not possible. INTERPRETATION: Available data indicate that the prevalence of PRMD in adult classical musicians is comparable to the prevalence of work-related musculoskeletal disorders reported for other occupational groups. Several recommendations for future research are outlined.     

Decreasing incidence and prevalence of rheumatoid arthritis in Pima Indians over a twenty-five-year period

OBJECTIVE: To evaluate temporal trends in the incidence of rheumatoid arthritis (RA). METHODS: Incident cases of RA were identified among a population-based cohort of Pima Indians in Arizona over the period 1965-1990. RESULTS: Among 2,894 subjects, 78 incident cases of RA were identified. The age-adjusted incidence declined by 55% in men (Ptrend = 0.225), and by 57% in women (Ptrend = 0.017) after controlling for oral contraceptive or estrogen use and for pregnancy experience. During the same period, age-adjusted prevalence rates of active RA decreased by 29% in men (Ptrend = 0.63) and by 40% in women (Ptrend = 0.02). Fewer than 17% of subjects with known RA were taking slow-acting antirheumatic drugs (SAARDs) in 1990. CONCLUSION: The decrease in incidence and prevalence of RA in this population over such a short period implicates the involvement of an environmental factor(s), other than exogenous estrogens, in the pathogenesis of the disease. However, the possibility that the observed decrease might be explained by an increased use of SAARDs in subjects with RA cannot be excluded.     

Clinical epidemiology of amyotrophic lateral sclerosis

The introduction of palliative therapies in amyotrophic lateral sclerosis (ALS) will alter the epidemiology of ALS as it is known now. Although incidence rates will remain unchanged in the near future, prevalence rates will likely increase dramatically. Better understanding of the age-specific presentation of motor neuron diseases worldwide will shed light on the vexing questions concerning the variable incidence rates in some countries and apparent incidence gradients in North America and Europe.     

Increasing bacteremia due to coagulase-negative staphylococci: fiction or reality?

BACKGROUND: The role of coagulase-negative staphylococci (CNS) in bacteremias continues to be controversial. Until the 1970s, CNS were mostly recognized as contaminants, being part of the cutaneous flora. Since then, several studies have reported increasing incidence and severity of infections due to CNS. PURPOSE: To review the literature concerning the epidemiology of CNS bacteremia in the United States and Europe with reference to the multiple definitions of infection versus contamination, considering the effect of potential biases influencing the validity of the reported results. METHODS: Literature search of the MEDLINE database from January 1980 to February 1998. Studies with fewer than 500 episodes of bloodstream infections or fewer than 100 episodes of CNS bacteremia were not included in the pooled analysis. RESULTS: (1) CNS remain the most frequent contaminants (58%-83% of positive blood cultures); (2) the proportion of all bloodstream infections caused by CNS is increasing (R=.51); (3) the overall incidence of true CNS bacteremia is increasing (R=.54, P=.0014); (4) comparing the United States to Europe, there is an increasing trend in the incidence of nosocomial bacteremia due to CNS in the United States (R=.82, P=.0006), but no trend is seen in European studies; (5) the mortality associated with true CNS bacteremia varies between 4.9% and 28%. DISCUSSION: This review confirms the increasing importance of CNS bacteremias, measured both as a proportion and as an incidence of bloodstream infections. The contributions of several possible explanations for the incidence increase and the difference between the United States and Europe need further evaluation: (1) increased recognition and awareness of CNS infections among clinicians; (2) a gradual change in the definition of true bacteremia from an obligatory two positive blood cultures to one positive blood culture associated with a clinical picture compatible with infection; (3) a change in blood culture practices and techniques; (4) an increase in the numbers of blood cultures performed, which is reported both in the United States and in Europe; (5) a shift toward more elderly patients with increasingly severe underlying illnesses; and (6) increasing use of intravascular devices. CONCLUSIONS: The apparent trend of increasing CNS bacteremia seems to be valid. Whether there is a real difference between the United States and Europe concerning the increase of CNS bacteremia is difficult to establish due to the large number of confounding factors. Few studies take into account the number of blood cultures performed or the use of intravascular devices to adjust for the observed trends. Further on-site surveillance studies are needed to investigate the phenomenon more extensively.     

Development of a quantitative risk assessment model for Salmonella enteritidis in pasteurized liquid eggs

Since Kraepelin delineated dementia praecox as a disease entity construct, epidemiological studies conducted since the beginning of the century have produced remarkably consistent estimates of its prevalence, incidence and lifetime risk across various populations and geographic areas. A similar pattern emerged from the WHO ten-country study on first-contact incidence of schizophrenia. The diagnostic concept of dementia praecox originally used by Kraepelin and that of schizophrenia employed in the WHO studies were found to overlap extensively, indicating continuity over time. However, the findings of a similar incidence of schizophrenia in diverse populations and across time periods are unusual for a multifactorial disease and are compatible with at least two alternative interpretations that have different implications for the search for genetic and environmental causes of the disorder.     

Influences on evaluability of radionuclide ventriculography in chemotherapy patients

We reviewed the incidence studies of intracranial tumors to compare their methodology and identify whether there was evidence of true differences in incidence by time, place, age, or sex. Studies were identified from Medline (1966-95), bibliographies of relevant articles, and personal knowledge. For each study, various methodological details were recorded, along with the age-standardized incidence of all primary tumors and the crude and age/sex-specific incidences of different types of intracranial tumor. Methodological factors which significantly influenced the reported incidence were identified and the results of different studies were compared and combined in a meta-analysis if appropriate. Twenty studies (over 20,000 primary tumors) were included. Higher incidences of primary tumors were found in studies that: used many methods to identify cases (odds ratio [OR] 1.92); included a high percentage of asymptomatic patients (OR 2.03); did not require histologic confirmation of the diagnosis (OR 1.69). Studies from the 1980's reported higher incidences than in previous decades (OR 1.51), probably because of improved methodology. Comparable studies from the 1980's gave widely different incidence rates for all primary tumors (7.1-18.6 per 100,000 per year). In all studies, the incidence of neuroepithelial and meningeal tumors increased dramatically with age. Neuroepithelial tumors were 40% more common in men, whilst meningeal and cranial nerve tumors were about 80% and 40% more common in women, respectively. Further incidence studies are required to establish geographical and secular variations in the incidence of primary intracranial tumors but these must use comparable methodologies. Provisional guidelines for future studies are given.     

The incidence of dementia: a meta-analysis

OBJECTIVE: To carry out a meta-analysis of the age-specific incidence of all dementias, including AD and vascular dementia. BACKGROUND: Several meta-analyses have been carried out on dementia prevalence, but none on its incidence. METHODS: We used loess-curve fitting to analyze data from 23 published studies reporting age-specific incidence data. RESULTS: The incidence of both dementia and AD rose exponentially up to the age of 90 years, with no sign of leveling off. The incidence rates for vascular dementia varied greatly from study to study, but the trend was also for an exponential rise with age. There was no sex difference in dementia incidence (p = 0.21), but women tended to have a higher incidence of AD in very old age, and men tended to have a higher incidence of vascular dementia at younger ages. East Asian countries had a lower incidence of dementia than Europe (p = 0.0004), and also tended to have a lower incidence of AD. CONCLUSIONS: The incidence of dementia rises exponentially to the age of 90 years. Any sex differences are small, and incidence is lower in East Asia than in Europe.     

Overweight in Switzerland. Cross-comparison of various studies with the Heureka Study

In this study the most important Swiss studies on the incidence of overweight and obesity are summarized and compared to the corresponding prevalence rates from the Heureka study. Interestingly, data on body weight indexes (mostly mass indexes) and the various prevalence rates showed good accordance for younger age groups. In the upper age classes however, phenotypic differences concerning determinants and risk factors for overweight became obvious in the different Swiss populations (i.e. from geographically different regions of Switzerland). Nevertheless, regional risk factors could not been detected because specific data were lacking. The importance of uniform weight definitions for studies as well as for daily practise is stressed.     

A systematic overview of the incidence of posterior capsule opacification

OBJECTIVE: Reported rates of posterior capsule opacification (PCO) vary widely and are based on various definitions of PCO, varying lengths and intervals of follow-up, and the use of different surgical techniques, intraocular lens (i.o.l.) designs, and methods of IOL implantation. This study was designed to obtain a more precise overall estimate of the incidence of PCO and to explore factors that might influence the rate of PCO development. DESIGN: A meta-analysis. METHODS: Published articles were selected for study based on a computerized MEDLINE search of the literature and a manual search of the bibliographies of relevant articles. Articles meeting selected inclusion criteria were reviewed systematically, and the reported data were abstracted and synthesized using the statistical techniques of meta-analysis. MAIN OUTCOME MEASURE: Pooled estimates of the proportion of eyes developing PCO at three postoperative timepoints--1 year, 3 years, and 5 years--were measured. RESULTS: There is significant heterogeneity among published rates of PCO. The overall pooled estimates (95% confidence limits) of the incidence of PCO were 11.8% (9.3%-14.3%) at 1 year, 20.7% (16.6%-24.9%) at 3 years, and 28.4% (18.4%-38.4%) at 5 years after surgery. There is no evidence of a significant decline in PCO incidence during the study period. CONCLUSIONS: Visually significant PCO develops in more than 25% of patients undergoing standard extracapsular cataract extraction or phacoemulsification with posterior chamber intraocular lens implantation over the first 5 years after surgery. Patient characteristics, surgical techniques, and differences in research design and reporting may account for some of the variability in reported rates. However, no specific factors were identified in the authors' analysis. More precise estimates of incidence and identification of risk factors for PCO will depend on the development of a standardized measurement of PCO and wider adoption of more rigorous study methodology.     

The association between epidemiological measures of the occurrence of asthma

SETTING: The prevalence of asthma is useful for studying the causes of asthma. OBJECTIVE: To ascertain whether there is a relationship between the prevalence and incidence of asthma. DESIGN: The association between age and the occurrence of asthma was analysed in an epidemiological study of 15,813 persons. RESULTS: Different conclusions were reached depending on whether the point prevalence, cumulative prevalence or the incidence rates were studied. The relation between the incidence and prevalence of asthma is described in two epidemiological models, and none of the models seem to fit empirical data. Furthermore, it is shown that estimating incidence rates by prospectively measuring the point prevalences may introduce a considerable bias if the reliability of the diagnosis of asthma is around or below an agreement of 99%, which is probably usually the case. Including asthmatic symptoms during the last year in the definition of point prevalence means that there is no simple relation between incidence rates and point prevalences. CONCLUSION: The point prevalence may be a biased measure in the study of the etiology of asthma, as there is no simple relationship between the incidence and prevalence of asthma.     

Stroke incidence, case fatality, and mortality in the WHO MONICA project. World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease

BACKGROUND AND PURPOSE: This report compares stroke incidence, case fatality, and mortality rates during the first years of the WHO MONICA Project in 16 European and 2 Asian populations. METHODS: In the stroke component of the WHO MONICA Project, stroke registers were established with uniform and standardized rules for case ascertainment and validation of events. RESULTS: A total of 13,597 stroke events were registered from 1985 through 1987 in a total background population of 2.9 million people aged 35 to 64 years. Age-standardized stroke incidence rates per 100,000 varied from 101 to 285 in men and from 47 to 198 in women. The combined stroke attack rates for first and recurrent events were approximately 20% higher than incidence rates in most populations and varied to the same extent. Stroke incidence rates were very high among the population of Finnish men tested. The incidence of stroke was, in general, higher among populations in eastern than in western Europe. It was also relatively high in the Chinese population studied, particularly among women. The case-fatality rates at 28 days varied from 15% to 49% among men and from 18% to 57% among women. In half of the populations studied, there were only minor differences between official stroke mortality rates and rates measured on the basis of fatal events registered and validated for the WHO MONICA stroke study. CONCLUSIONS: The WHO MONICA Project provides a unique opportunity to perform cross-sectional and longitudinal comparisons of stroke epidemiology in many populations. The present data show how large differences in stroke incidence and case-fatality rates contribute to the more than threefold differences in stroke mortality rates among populations.     

Extra-articular manifestations of rheumatoid arthritis: risk factors for serious gastrointestinal events

OBJECTIVES: Serious upper gastrointestinal events are an important threat to patients with arthritis who are treated with non-steroidal anti-inflammatory drugs (NSAIDs). In this study risk factors for serious upper gastrointestinal events are identified in patients with possible or definite rheumatoid arthritis (RA). METHODS: A retrospective analysis of factors that might contribute to the risk of serious upper gastrointestinal events was performed in a cohort of 2315 consecutive patients with possible or definite RA. The relative influences of disease severity, drug treatment, particularly with corticosteroids, and history of peptic ulceration were analysed with a conditional logistic regression model for the 106 patients with serious upper gastrointestinal intestinal events and for an equal number of control patients who were matched for age, gender, number of criteria for RA, and disease duration. RESULTS: The incidence rate for serious upper gastrointestinal events was 4.0/1000 patients in each year. The study reconfirmed that age over 60 years, history of peptic ulceration, and use of corticosteroids are risk factors. The presence of extra-articular manifestations of RA was associated with a two to 11-fold increase in the risk for serious upper gastrointestinal events. This risk was independent of the use of corticosteroids. CONCLUSION: Disease severity, in particular the presence of extra-articular features, may be an important factor in the pathogenesis of upper gastrointestinal ulceration in patients with RA who are treated with NSAIDs.     

Geographic variation in mortality among individuals with youth-onset diabetes mellitus across the world. DERI Mortality Study Group. Diabetes Epidemiology Research International

The aim of this study was to evaluate the geographic variation in mortality among individuals with youth-onset insulin-dependent diabetes mellitus (IDDM) across the world. The study was based on the currently available IDDM incidence and mortality data. Mortality data for diabetes in the 0-24 year age group were obtained from the World Health Organization (WHO) statistics. The mortality rates were adjusted for the frequency of occurrence of IDDM and dividing the mortality rates by the IDDM incidence rates which were obtained from the WHO DiaMond project. There was a more than 10-fold geographic variation in mortality between the developed countries and Eastern European populations. The areas with the highest mortality rates were located in Japan, Eastern Europe and Russia. The areas having the best outcome associated with IDDM were Northern Europe, Central Europe, and Canada. An ecological study demonstrated a relationship between the incidence-adjusted mortality (estimated case-fatality) with IDDM incidence itself (Spearman's correlation coefficient = 0.45) as well as infant mortality and life expectancy at birth. These data demonstrated the possibility of an enormous geographic variation in mortality of youth-onset diabetic patients even in developed countries. It is important to note that these excess deaths are potentially preventable. The ecological study also suggested that the mortality differences may be in part related to overall and diabetes related care.     

Secondary prevention for ischemic heart disease. Relative numbers needed to treat with different therapies

Secondary prevention of ischemic heart disease refers to the process of preventing further morbidity and reducing mortality rates in patients with clinical manifestations of the disease. Twenty-five large randomized, clinical trials addressing mortality rates and cardiovascular morbidity in patients with established ischemic heart disease are reviewed. Broadly defined, these were trials of aspirin and antiplatelet agents, anticoagulants, beta-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, lowering of cholesterol levels, exercise rehabilitation, and diet or vitamins. In trials using warfarin sodium, timolol maleate, propranolol hydrochloride, captopril, ramipril, and simvastatin and 2 diet studies, statistically significant improvements in total mortality rates were seen. Most other studies showed non-significant reductions in total mortality rates, with statistically significant reductions in 1 or more measures of cardiovascular morbidity. The methods necessary for the reader to calculate the number (of patients) needed to treat for other studies are also reviewed. The uses and limitations of the number needed to treat as a method to compare studies of different interventions in similar populations are discussed.     

The South African HIV epidemic, reflected by nine provincial epidemics, 1990-1996

OBJECTIVES: To determine by serological examination the annual point prevalence rates of infection with the human immunodeficiency virus (HIV) in representative samples of subjects in the nine provinces of South Africa, 1990-1996. DESIGN: Annual cross-sectional point prevalence surveys conducted in October/November of each year. SETTING: South Africa, including areas that used to be known as self-governing and independent National States. SUBJECTS: Pregnant women in the age group 15-49 years who attend antenatal clinic services provided by the public health services, and who act as an indicator group of the HIV epidemic among the heterosexually active population. OUTCOME MEASURES: HIV positivity as determined serologically; done consistently over several years, this serves to monitor the distribution and trend of the HIV epidemic in each of the nine provinces of South Africa. RESULTS: Empirical data gained from seven annual, consecutive countrywide surveys demonstrate a wide geographical variation in the point prevalence rates of HIV infection. In October/November 1996 the point prevalence rates (%) were as follows: Western Cape 3.09, Northern Cape 6.57, Northern Province 7.96, Eastern Cape 8.10, Gauteng 15.49, Mpumalanga 15.77, Free State 17.49, KwaZulu-Natal 19.90 and North West 25.13. The weighted national average was 14.17%. There are indications that some of the provinces (KwaZulu-Natal and possibly Mpumalanga) might have passed a point of inflection suggesting deceleration in their specific rates of increase. These results are, however, counterbalanced by the exponential growth still being experienced in provinces with large populations such as Gauteng and the Eastern Cape. It is concluded that the net effect of these divergent trends currently affects the national figure only marginally. A major deflection from the exponential growth patterns seen hitherto can be anticipated only once all or most of the highly populated provinces have traversed their respective points of inflection. The exponential model significantly explains the HIV epidemics in the provinces. The combination of these provincial epidemics describes the initial exponential phase of the epidemic.     

Rheumatoid arthritis and the risk of malignancy

OBJECTIVE: To determine the relative risks of malignancy and of site-specific malignancies in patients with rheumatoid arthritis (RA). METHODS: In a prospective cohort study, 862 patients with RA (96% white) were enrolled from 1966 to 1974 and were followed up for up to 35 years (mean 17.4 years) at the University of Saskatchewan Rheumatic Disease Unit. All diagnoses of cancer were cross-referenced with the Provincial Cancer Registry. Expected cancer incidence rates were determined based on province of Saskatchewan population statistics matched to each study patient for age, sex, and calendar year. Standardized incidence ratios (SIRs) of the observed-to-expected cancer incidence and 95% confidence intervals (95% CI) were then calculated. RESULTS: A total of 136 cases of cancer were observed compared with 168 expected (SIR 0.80, P = 0.011 [95% CI 0.67-0.95]). The relative risk of colorectal malignancy was significantly reduced in the RA study population (SIR 0.52, P = 0.037 [95% CI 0.25-0.96]). A significant excess of leukemia was found (SIR 2.47, P = 0.026 [95% CI 1.12-4.69]), whereas the incidence rates for Hodgkin's disease and non-Hodgkin's lymphoma and all other site-specific malignancies were not found to be significantly different from general population rates. CONCLUSION: In our cohort of RA patients, colorectal cancer was detected in only half the expected number of patients. This risk reduction may be related to long-term nonsteroidal antiinflammatory drug (NSAID) use in RA, as has been suggested in several other studies of long-term NSAID use. An increased risk of leukemia was confirmed. This may be due to the persistent immune stimulation associated with RA itself, since other potential explanatory factors for increased leukemia were not apparent. Despite the excess of hemopoietic malignancy and despite treatment of RA with potentially oncogenic agents, the overall risk of malignancy was reduced in this RA cohort.     

Inhibition in a microgravity environment of the recovery of Escherichia coli cells damaged by heavy ion beams during the NASDA ISS phase I program of NASA Shuttle/Mir mission no. 6

OBJECTIVE: To explore whether there are different disease patterns of rheumatoid arthritis (RA) in women and men. METHODS: We studied 55 male case patients and 110 female control patients who developed RA between 1970 and 1985 and who resided and received medical care in Olmsted County, Minnesota, for at least 10 years after the diagnosis of RA. Case and control patients were matched for the date of first diagnosis. The pattern and extent of joint involvement, the frequency of joint surgeries, and the presence and type of extraarticular manifestations were determined by retrospective chart review. RESULTS: Incidence rates in women were variable and age dependent, whereas the risk in men older than 36 years was constant over their lifetime. Erosive disease was more frequent in men than in women (72% versus 55%, respectively; P < 0.05) and tended to occur earlier (47% versus 31% for erosive disease within the first 4 years of RA). Although male sex was correlated with a higher risk of bony erosions and an accelerated course of RA, structural consequences of joint destruction were more pronounced in women. Joint surgery was performed more frequently in women (50%) than in men (27%) (P = 0.01). In particular, the frequencies of arthroplasties and arthrodeses of hand and foot joints were different (34 procedures in women versus 1 procedure in men; P < 0.001). Sex influenced the risk as well as the pattern of organ involvement in RA. Nodules and rheumatoid lung disease were typical manifestations in men (P = 0.001 and P < 0.001, respectively), whereas women typically developed sicca syndrome (P = 0.05). Despite differences in disease aggressiveness and disease pattern, there was little difference in the medical therapy in the men compared with the women. CONCLUSION: RA is a heterogeneous disease with variations in phenotype. Sex-associated factors influence disease severity as well as disease pattern. Because sex-related effects influence treatment goals, treatment responses, and side effects, they should be considered in clinical study design and analysis as well as in the treatment decisions for individual patients with RA.     

Cariogenicity depends more on diet than the prevailing mutans streptococcal species

This review aims to compare the occurrence and distribution of mutans streptococci in Africa, Europe, and North America and in addition will try to offer explanations for existing relationships among salivary mutans streptococci counts, dietary patterns, and dental caries. The literature reveals that salivary mutans streptococci counts in child populations of the three continents are comparable. The distribution of mutans streptococci species, with a predominance of S. mutans followed by S. sobrinus, and the virtual absence of other mutans streptococci species are also comparable. Although it is widely believed that diet has an important effect on mutans streptococci counts, this review provides evidence that this does not hold true when variations in dietary patterns are moderate, as they normally are in real-life situations. Since the diets of the child populations in the three continents vary moderately, a strong dietary-induced effect on salivary mutans streptococci counts cannot be expected. The observed analogous salivary mutans streptococci counts in these child populations are thus 'not surprising' but are in accordance with the conceptual expectation. The differences in caries experience in children of the three continents cannot be explained by the prevailing mutans streptococci species but instead should be attributed to differences in the cariogenicity of the various diets. The fact that the cariogenicity of the diet determines the development of dental caries while hardly affecting the mutans streptococci counts explains the limited value of the latter as an indicator of dental caries. The reviewed literature shows that mutans streptococci are ubiquitous in children aged 7 years and older in Africa, Europe, and North America. Mutans streptococci should therefore be considered as belonging to the indigenous microflora of the human mouth.