Clin. Otolaryngol. 1990, 15, 125-131

Laryngeal papillomas: the epidemiology in a Danish subpopulation 1965-1984 HENNING LINDEBERG AND OLE E L B R 0 N D Department of Otorhinolaryngology, University Hospital, Aurhus. Denmark

Accepted f o r publication 5 December 1988

LINDEBERG H.& ELBR0ND 0.(1990) Cf&. Otolaryngof. 15, 125-131 Laryngeal papillomas: the epidemiology in a Danish subpopulation 1965-1984 The incidence rate of laryngeal papillomas in a Danish subpopulation (approximately 2.8 million inhabitants) was 3.84 x per year in the period 1968-1984. For juvenile papillomas the incidence rate was 3.62 x compared with 3.94 x for laryngeal papillomas of adult onset. When comparing different time periods a significantly low incidence was found in the time 1965-1968, while the incidence remained constant in 1969-1984. The low incidence rate in the early period may be real, but selectional bias may have played a part. It is in general anticipated that maternal genital HPV-infections may serve as an HPV-reservoir, and that juvenile laryngeal papilloma is a result of HPV transmission from the mother to the child during birth. In the period in question cervical HPV-infections have been recorded with increasing frequency in younger women, indicating that the prevalence is rising. However, this is not reflected in the incidence of laryngeal papillomas. Keywords laryngeal papillomas HPV

Laryngeal papillomas are, beyond any reasonable doubt, caused by human papillomavirus (HPV), preferentially types 6 and 1 l,I-* which are also found in condylomatous lesions of the uterine cervix.9 It is anticipated that HPV is transferred from a mother with condylomatous lesions to her child, during or even before birth, causing juvenile laryngeal papillomas later.2-6~'0~" In the last decades the frequency of genital HPV-related lesions (condylomas and cervical intraepithelial neoplasia or CIN) apparently has been increasing in Denmark as well as in other countries. Against this background we decided to examine the incidence of laryngeal papillomas in Denmark over a prolonged period.

incidence epidemiology human papillomavirus

Material and methods SELECTION O F PATIENTS

Recently we published a series of 23 1 laryngeal papillomas.'2 From this material all patients with onset between 1965 and 1984 were selected. Only patients who lived in Funen or Jutland at first presentation were included in the present study. This area has a total population of approximately 2 800 000 inhabitants, comprising about 50% of all Danes. The patients were classified as juvenile or adult according to age of onset (age < 20 years at first presentation were considered juvenile), and as solitary or multiple as described previ~usly.l**'~

Correspondence: H. Lindeberg, Department of Oral Pathology, Royal Dental College, Vennelyst Boulevaard, DK-8000 Aarhus C, Denmark

125

I26

H . L I N D E B E R G A N D 0. E L B R B N D

squared test (without Yates’ correction), and P-values below the 5% level were considered significant. Using the observed number and the standard population, the expected incidence for each period was calculated (indirect standardization). The Standard Incidence Rate (SIR, a parallel to Standard Mortality Rate) was computed as Number of expected new cases x 100 Number of observed new cases The confidence limits (5%) of SIR was calculated as15

50

401n I

R 3011 B E

2

n

20 10 0-3 10-19 20-29 33-39 40-49 52-53 60-69 70-79 80+

Age (years)

Figurel. Sex distribution and age of onset of 181 patients with laryngeal papillomas from Funen and Females; m, males. Jutland, 1965-1984. 0,

loo

(xR)l*(L.96’43

EPIDEMIOLOGICAL METHODS

The time from 1965 to 1984 was divided into 5 periods of 4 years each: 1965-68, 1969-72, 1973-76, 1977-80 and 1981-84. For each period the population at the middle was recorded, considering age intervals of 5 years for children ( < 20 years old), ~ and of 10 years intervals for a d ~ 1 t s . IFor 1965-68, the population at the middle of the period had to be estimated by extrapolation from the figures from 1965 and 1970/ 71. A standard population (with respect to age and sex) was computed as the mean of 4 periods, excluding 1965-68. (The reason for excluding this period is mentioned in the discussion.) Age-specific incidence rates for multiple as well as for solitary papillomas were calculated for the period 1969-84. The incidence of papillomas in each of the 5 periods was compared with the expected number, computed from the age-specific incidence for 1969-84. Expected and observed numbers were compared using the Chi-

Results The material consisted of 181 patients from Funen and Jutland with laryngeal papillomas with first presentation 1965-84 (Figure 1). The female to male ratio in the juvenile group was 22:29, which does not deviate from an expected 1 : 1-ratio (x2 = 0.96). In the group of adult papillomas a male preponderance was present, F: M = 32: 98, x2 = 33.5, P

Laryngeal papillomas: the epidemiology in a Danish subpopulation 1965-1984.

The incidence rate of laryngeal papillomas in a Danish subpopulation (approximately 2.8 million inhabitants) was 3.84 x 10(-6) per year in the period ...
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