Prevalence rate

Prevalence is thus not a true rate but simply a proportion, although the term prevalence rate is used. 

In population-based studies from the USA, self-reported peanut allergy in children rose from 0.4% in 1997 to 0.8% in 2002 [21]. In the UK, prevalence rates for peanut allergy are in excess of 1%. Data from England points in the same direction with a twofold increase in reported peanut allergy. 

The lifetime prevalence rate for panic disorder is about 1.7%, divided into 2.4% in women,... 

The mortality rate in pregnant women with acute infections may reach 25%. Rarely does HEV cause endemics in industrialized countries, where the prevalence rate is 1% to 5%.18,19... 

Prevalence rates for a variety of different types of pain have been described. The annual incidence of moderate-intensity back pain is 10% to 15% in the adult population with a point prevalence of 15% to 30%.3 Migraine affects more than 25 million Americans, and 90% of Americans report some other types of headaches (e.g., tension or sinus) each year.4 Pain resulting from fibromyalgia affects 4 million Americans.5 Cancer is commonly associated with both acute and chronic pain, and about 70% of those diagnosed with cancer will experience significant pain.6... 

Psychotic symptoms in late life (greater than 65 years of age) are generally a result of an ongoing chronic illness carried over from younger life however, a small percentage of patients develop psychotic symptoms de novo, defined as late-life schizophrenia. The 6-month prevalence rate of schizophrenia in the elderly is around 1%. However, other illnesses presenting with psychotic symptoms are common in this population, as approximately one-third of patients with Alzheimer s disease, Parkinson s disease, and vascular dementia experience psychotic symptoms. The majority of data for antipsychotic use in the elderly comes from experience treating these other disease states. 

Lifetime prevalence rates of psychiatric comorbidity co-existing with bipolar disorder are 42% to 50%.16 Comorbidities, especially substance abuse, make it difficult to establish a definitive diagnosis and complicate treatment. Comorbidities also place the patient at risk for a poorer outcome, high rates of suicidal-ity, and onset of depression.2 Psychiatric comorbidities include ... 

NCS-R show that while, in general, prevalence rates across the anxiety spectrum increase from the younger age group (18-29) to older age groups (30-44 and 45-59), rates are substantially lower for those older than age 59.3... 

Non-REM parasomnias have variable prevalence rates depending on patient age and different diagnoses. Sleep talking, brux-ism, sleepwalking, sleep terrors, and enuresis occur more frequently in childhood than in adulthood. Nightmares appear to occur with similar frequency in adults and children. REM behavior disorder (RBD), an REM-sleep parasomnia, has a reported prevalence of 0.5% and frequently is associated with concomitant neurologic conditions.16 Chronic RBD is more common in elderly men and may have a familial disposition. 

Giardia lamblia (also known as G. intestinalis or G. duode-nalis), an enteric protozoan, is the most common intestinal parasite responsible for diarrheal syndromes throughout the world. Giardia is the most frequently identified intestinal parasites in the United States, with a prevalence rate of 5% to 15% in some areas. G. lamblia has been identified as the first enteric pathogen seen in children in developing countries, with prevalence rates between 15% and 30%. 

Chia et al. 1995a). Another index of exposure examined was the number of times the PbB level was above critical values (e.g., 40, 50, 60 ig/dL). Serum P2 X -globulin was the only marker showing a significantly higher prevalence rate ratio of abnormalities (increase) among lead-exposed workers. 

The development of mild forms of anxiety and neuroveg-etative and/or cognitive responses to stress may represent an adaptive evolutionary step against environmentally (external) or self-triggered (internal) threats, but maladaptive reactions have also emerged in human evolution. Thus, anxiety disorders are maladaptive conditions in which disproportionate responses to stress, or even self-evoked responses, are displayed. Anxiety disorders are one of the most frequent psychiatric illnesses, and have a lifetime prevalence of 15- 20% [1, 89]. The most common presentations are generalized anxiety disorder, with a lifetime prevalence rate of close to 5% [1, 89] social anxiety disorder, with very variable lifetime prevalence rates ranging from 2 to 14% [90] panic disorder, with rates from 2 to 4% [1,89] and post-traumatic stress disorder (PTSD), with a prevalence rate close to 8%. Specific phobias, acute stress and obsessive-compulsive behavior are other clinical presentations of anxiety disorders. 

Measures of the public health importance of a disease include the absolute number of cases, the incidence rate, the prevalence (rate), the economic impact of the disease, and the prognosis and preventability of the disease.65 Contact dermatitis is the most common occupational and environmental skin disease. Epidemiologic data show that contact dermatitis comprises 90 to 95% of all occupational skin diseases. 

Although these different populations are known to have higher than average prevalence rates for drug problems, they do not seem to be seeking treatment or... 

The prevalence rates of schizophrenia are lower in old age than in younger age groups (Copeland et al. 1998). The incidence of Alzheimer s disease with psychosis is much more frequent than the incidence of schizophrenia in old age (Jeste and Finkel 2000). For the frail Alzheimer s patients, medications may induce or aggravate the symptoms. 

Major depressive disorder is among the most common psychiatric syndromes affecting approximately one in four American women and one in ten American men during their lifetimes. Although the overall prevalence rates have stabilized, the average age of onset for the disorder has decidedly decreased. Numerous risk factors for depression have been identified and are listed in Table 3.3. 

Gallstones are a common clinical finding in Western populations, the prevalence rate in Europe being 10-15%. Whilst 80% of cases are asymptomatic from their gallstones, 2% develop complications such as cholecystitis and require surgery. ... 

Psychotic symptoms, particularly hallucinations (predominantly visual and to a lesser extent auditory), are common in DLB. Prevalence rates have varied from between 13% (Byrne et al., 1989) and 80% (McKeith et al., 1992). However, these discrepant figures may reflect the specialty setting of the clinical populations lower prevalence rates being associated with neurological services compared with psychiatric services. 

A particularly interesting analysis involves lizuka s evaluation of the effect of potential (as opposed to actual) market size on a drug s DTCA spending. Using data from the U.S. National Flealth Interview Survey on prevalence rates for selected chronic conditions based on annual household and other surveys, lizuka related potential market size to the primary treatment indication for each drug. This potential market size was the sum of treated plus untreated individuals. 

Table 2 Prevalence rates of anxiety disorders in the general population according to DSM-III, DSM-III-R and DSM-IV... 

Looking now into the prevalence rates reported from the several studies, lifetime prevalence rates for all anxiety disorders lumped together in the different studies range between 5.6% and 28.7%. The estimated median of the included studies is 15.1%. Lifetime prevalence estimates describe the proportion of persons in the population who have developed the disorder under consideration at least once in their life. Based on this estimated median, anxiety disorders occur in approximately 1 in 7 persons in the general population at some point in their life. Looking closer at specific anxiety disorders, it becomes evident that the high hfetime prevalence of anxiety disorders is mostly due to the high frequency of simple phobia and social phobia. 

Table 2 also indicates that the prevalence estimates for 12-month, 6-month and point prevalences are lower when compared to the Ufetime estimates. This can be seen as one indicator of the fluctuating character of anxiety disorders. As discussed above, variation across studies is probably mainly due to differences in study characteristics. OveraU, the 12-month prevalence rates for any anxiety disorder result in an estimated median of 11%, indicating that 1 in 10 people were affected by an anxiety disorder in the year preceding the assessment. 

According to the U.S. Department of Health and Human Services, 1.4 million cases of child maltreatment are reported annually, with 160,000 children suffering serious injuries and 2000 children dying each year as a consequence of maltreatment. Prevalence rates have been evaluated for different types of abuse in clinical, community, and national samples. Prevalence rates of sexual abuse range from 7%-62% in women (McCauley et al., 1997). A reanalysis of 166 studies on the prevalence of sexual abuse in boys revealed rates from... 

Children with pervasive developmental disorders are also at higher risk for developing TS. In a recent survey of 447 pupils from nine schools for children and adolescents with autism, 19 children were found to have definite TS, yielding a prevalence rate of 4.3% (Baron-Cohen et ah, 1999). However, caution is warranted, as complex motor tics can be difficult to distinguish from motor stereotypies, and differentiation among these behaviors may be especially problematic among retarded individuals with limited verbal skills. 

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