Unit 2 – Incidence, Prevalence, & Variability; incidence/prevalence, studies, onset, spontaneous recovery, gender ratio

Incidence

is the rate of occurrence of a given disorder or disease in a specified group of people

Prevalence

is the number of individuals who currently have a disorder or disease

Incidence studies

starts with a healthy or normal group; repeatedly observes the same individuals over a period of time and counts the number of individuals who begin to show the disease or the disorder

Incidence studies misc

Studied by the longitudinal method/Is a predictive statement/Incidence studies are more expensive than prevalence studies

Prevalence studies

starts with clinical records of individuals who already exhibit the disorder; collects information from various sources and adds numbers

Prevalence studies misc

Involves a head count/Uses a cross-sectional method of study/Is not a predictive statement; it is a statement of current number of persons with the disorder/ Studies are less expensive than incidence studies

INCIDENCE VS. PREVALENCE OF STUTTERING

There are fewer studies of incidence of stuttering/ Most available are prevalence studies/ Incidence is less likely to be accurate due to the difficulty of attaining valid longitudinal data/Most studies are rough estimates

Andrews & Harris (1964)

Incidence study;studied 1,142 babies in England and tracked them from birth to their 16th birthday;43 children exhibited stuttering, amounting to 4.9% more than any other study; This study has influenced the generally accepted notion that the lifetime; incidence of stuttering is approximately 5%

More recent incidence studies indicate a trend up from

5% to a central figure of 8% -11% Important to emphasize data obtained

Most valid data based on age is

childhood

Many researchers (Yairi & Ambrose (2013), Bloodstein & Ratner (2008)) believe that

lifetime incidence could be at least 10%

PIONEER REPORTS

Early investigation around 100 years ago

Four large studies with a total of 660,000 participants revealed

Lindberg (1900) Danish - .90%; Von Sarbo (1902) Hungarian - 1.02%; Hartwell (1895) American, Boston - .77%; Conradi (1904) American - .77% GROUP MEAN = .89%

PREVALENCE CHART FROM YAIRI & SEERY (2015)

prevalence of stuttering are consistent with studies done after Pioneer studies; Studies on prevalence performed on just preschool age children yield higher prevalence rates; prevalence of stuttering is 0.72% in general U.S. population

ONSET OF STUTTERING

majority begin in early childhood; generally appears after normal fluency skills demonstrated; Widely accepted vast majority of stuttering begins ages 2-4; In one study of 179 stuttering children, only 5 had onset after age 4 (Mansson, 2000)

Spontaneous recovery

Natural Recovery;Some children or adolescents recover from stuttering without professional help

Spontaneous recovery data applies to

groups not individual clients

Is it possible to predict spontaneous recovery

no

Predictors of recovery from stuttering include

Early age of onset/Family members who have recovered from stuttering/Good phonological and language skills

Gender ratio is more common in

males than in females

At the onset of stuttering, the ratio may be

2;1

The most frequently cited ratio is

3;1 (male; female) for children in earlier elementary grades

The gender ratio is larger in what grades

higher, (perhaps 4;1)