Period prevalence

In 1988, the National Health Interview Survey (NHIS) included an Occupational Health Supplement, which included questions on dermatitis. The survey consisted of personal interviews of people in randomly selected households. For 30,074 people participating in the NHIS, the period prevalence for all forms of dermatitis was 11.2% and for contact dermatitis was 2.8%. Projecting these results to the U.S. working population resulted in an estimate of 13.7 million people with dermatitis and 3.1 million people with contact dermatitis.67... 

Since 1938, asthma has been a disqualifying condition for submarine duty. However, a recent study reported that there is a 0.16% annual-period prevalence in the active duty enlisted Atlantic Fleet Submarine Force (Sims et al. 1999). Because asthma can develop in people during their 20s and 30s, it is possible that the condition can be diagnosed in some individuals after they are assigned to submarine duty. In most cases, submarine crew members who do have asthma exhibit only mild symptoms. It is not known whether the submarine atmosphere poses an occupational asthma risk Crew members with asthma are likely to be... 

Cotch MF, Hoffman GS, Yerg DE, Kaufman Gl, Targonski P, Kaslow FJA (1996) The epidemiology of Wegener s granulomatosis Estimates of the five-year period prevalence, annual mortality, and geographic disease distribution from population-based data sources. Arthritis Rheum, 39(1) 87-92. 

Large-scale, epidemiologic cross-sectional trials are too cost-intensive to be used as an instrument for regular monitoring of IDD. Instead of cross-sectional trials, periodic prevalence surveys are an adequate method to evaluate changes in goiter prevalence/UI over time (WHO, 2001). 

Periodic prevalence surveys for goiter are an adequate method to evaluate changes. 

Pindborg, J.J., Studies in oral leukoplakia a preliminary report on the period prevalence of mahgnant transformation in leukoplakia based on a follow-up study of248 patients, J. Am. 

The point prevalence includes only subjects with actual OCD. Since OCD is often a chronically relapsing disease, the point prevalence is therefore less informative than the period prevalence. However, the accuracy of recall will decrease with time, because persons who did not have complaints recently are more likely to forget to report their earlier contact dermatitis. 

The period prevalence includes subjects with long-lasting contact dermatitis as well as relatively recent cases and thus possesses all interpretational difficulties that are inherent to a period prevalence. No inference can be made between exposure and contact dermatitis because the exposure may have changed over time, past exposure may be over- or underestimated, and preventive measures may have been taken after symptoms occurred. Given these considerations, incidence figures are preferred for analyzing risk factors for OCD. 

Prevalence is the total number of active (existing and new) cases of the disease in a defined population, either during a specified period (period prevalence) or at a specified point in time (point prevalence). The prevalence nosocomial infection rate is calculated simply by dividing the number of active nosocomial infections in patients surveyed by the number of patients surveyed. Because nosocomial pneumonias occur relatively infrequently, the period chosen for surveillance must be large enough for an adequate estimation of a hospital s prevalence rate and usually varies depending on the number of occupied beds in a hospital. In addition, these rates require risk adjustment, which is currently not available for interhospital comparison of prevalence rates. 

Rubidium [7440-17-7] Rb, is an alkali metal, ie, ia Group 1 (lA) of the Periodic Table. Its chemical and physical properties generally He between those of potassium (qv) and cesium (see Cesiumand cesium compounds Potassium compounds). Rubidium is the sixteenth most prevalent element ia the earth s cmst (1). Despite its abundance, it is usually widely dispersed and not found as a principal constituent ia any mineral. Rather it is usually associated with cesium. Most mbidium is obtained from lepidoHte [1317-64-2] an ore containing 2—4% mbidium oxide [18088-11-4]. LepidoHte is found ia Zimbabwe and at Bernic Lake, Canada. 

With the current prevalence of computer Hterature searching, it is relatively easy to accomplish patent searches, especiaUy in Chemicaly hstracts (CAS). In heu of what would be an extensive Ust of patent references to the many appHcations for VP homo- and copolymers, a Ust of the major categories and the number of patents granted in each of them during the period 1989—1995 is given in Table 17. More detail concerning the patents is provided in Reference 27. 

Plasmodium vivax, responsible for the most prevalent form of malaria (benign tertian), has an incubation period of 8—27 days (14 average). A variety seen in northern and northeastern Europe has an incubation period as long as 8—10 months. The disease can cause splenic mpture and anemia. Relapses (renewed manifestations of erythrocytic infection) can occur with this type of malaria. Overall, P. vivax is stiU susceptible to chloroquine however, resistant strains have been reported from Papua New Guinea and parts of Indonesia. Plasmodium malariae the cause of quartan malaria, has an incubation period of 15—30 days and its asexual cycle is 72 hours. This mildest form of malaria can cause nephritis in addition to the usual symptoms. It is a nonrelapsing type of malaria but the ted blood ceU infection can last for many years. No resistance to chloroquine by this plasmodium has been reported. Plasmodium ovale responsible for ovale tertian malaria, has an incubation period of 9—17 days (15 average). Relapses can occur in people infected with this plasmodium. No chloroquine resistance has been reported for this parasite. 

World coal usage, inclusive ot the three major types of coal—anthracite, bituminous (by far the most prevalent form) and lignite—reached a plateau in the first decade of the twentieth centuiy and climbed only very slowly in the half century that followed. By 1880, coal use had equaled wood use on a worldwide basis. The usage around the turn of the centuiy was on the order of 2.2 gigatons per year (around 55 quads), of which about 600 million tons were in the United States. World oil production progressively supplemented the use of coal between 1900 and 1950, increasing by more than an order of magnitude in that period of time, from a little over a quad to some 20 quads. Coal s increase over those years was fractionally much less. 

In the early period of the pandemic, before the development of sensitive and reliable instruments to diagnose early infection, only patients with advanced AIDS presented to health care facilities. As a result, the estimates and projects of the costs for HIV/AIDS patients based on observed health care utilization were high. For example, Scitovsky and Rice estimated the annual costs of AIDS care in the United States in 1985, 1986, and 1991 to be US 630 million, US 1.1 billion, and US 8.5 billion, respectively these costs represented the direct and indirect costs of HIV infections (Scitovsky and Rice 1987 Scitovsky 1988, 1989). More than 80% of these costs stemmed from losses in productivity, a reflection of the fact that AIDS has afflicted primarily working-age adults. The great increase in total costs by 1991 is caused by a projected increase in the prevalence. 

Lack of repeatability of the results of metabolic studies using laboratory strains that have been maintained by repeated transfer for long periods under nonselective conditions may be encountered. These strains may no longer retain their original metabolic capabilities, and this may be particularly prevalent when the strains carry catabolic plasmids that may have been lost under nonselective conditions. For these reasons, strains should be maintained in the presence of a cryoprotectant such as glycerol at low temperatures (-70°C or in liquid Nj) as soon as possible after isolation. Freeze-drying is also widely adopted, and is recommended. 

Tension-type headache (TTH) is the most common primary headache disorder. It is often underrepresented in clinical practice, as many patients do not present for care.6 The term tension-type headache is used to describe all headache syndromes in which muscle contraction is the most significant factor in the pathogenesis of pain. The 1-year prevalence of TTH in the population ranges from 30% to 90%.6 It is more common in adult females. Environmental factors, as opposed to genetic predisposition, play a more central role in their development. Tension-type headaches can be further divided into episodic or chronic the mean frequency of attacks is 3 days per month in episodic disorders, and chronic TTH is defined as 15 or more attacks in a 1-month period.7 The estimated prevalence of chronic TTH is less than 5%.6 Some researchers believe that chronic TTHs represent a continuum of headache severity with migraine headache.8 When severe headaches are difficult to differentiate clinically, treatment should initially target TTH. 

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