Determinants of sexual habits in Italian females

Transcription

1 394 Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy F Parazzini L Cavalieri d'oro E Negri C La Vecchia Ii Clinica Ostetrico Ginecologica, Universita di Milano, Milan, Italy F Parazzini Clinica Dermosifilopatica, Universita di Milano, Ospedali Riuniti di Bergamo, Italy L Cavalieri d'oro Institute of Social and Preventive Medicine, University of Lausanne, 5 Lausanne, Switzerland C La Vecchia Address correspondence to: Dr Fabio Parazzini, Istituto di Ricerche Farmacologiche "Mario Negri" via Eritrea, 6, 57 Milano. Genitourin Med 99;68: Fabio Parazzini, Luca Cavalieri d'oro, Eva Negri, Carlo La Vecchia Abstract Objective-To identify characteristics of women reporting multiple sexual partners and early age at first intercourse in Italy. Method-Information on 39 control women (median age 54 years) interviewed as part of a case-control study of cervical neoplasia conducted in the greater Milan area, rthern Italy were analysed using stratified analysis and multiple logistic regression. Results-Overall, 8% ofthe study sample reported no more than one sexual partner, % two and 9/o three or more. The proportion reporting multiple sexual partners tended to be higher among younger and more educated women (4% vs 9%/o of women with respectively less than 7 and or more years of education reported three or more partners). smokers reported a higher number of sexual partners than never smokers. The proportion of nulliparae reporting three or more sexual partners was higher than that ofparous women. These findings were confirmed after taking into account in a multivariate analysis -the- role- of potential-- confounding factors. Furthermore similar findings emerged from an analysis restricted to women aged 4 years or less. Always considering number of sexual partners, no relationship emerged with marital status, spontaneous or induced abortions, lifetime number of reported Pap smears and contraceptive habits. With reference to age at first intercourse, 5% of the study population reported their first intercourse at age 8 or before, 34% between 9 and years, and 4% at age 3 or later. Younger women (that is, more recent cohorts) more frequently reported earlier age at first intercourse and the proportion of never married women reporting early intercourse was higher (5% vs % of never married vs married women). relationship emerged between education, smoking habits, parity, history of spontaneous or induced abortions, number of Pap smears, contraceptive habits, and age at first intercourse. Conclusion-This study documents conservative sexual habits in rthern Italian females (at- least on the basis of self reporting) but indicates that any educational compaigns towards safe sex should be focused towards younger women, particularly smokers, unmarried and nulliparae. (Genitourin Med 99;68: ) Introduction Over the past few years the spread of HIV infection in the general population through heterosexual intercourse -3 and the increasing diagnosis in several developed countries of genital infections, including human papilloma virus (HPV) and herpes virus simplex (HVS) infection, have aroused the interest of the scientific community and health planners in sexually transmitted diseases.4 ' In the absence of effective therapy for viral infections, special emphasis has been laid on information and preventive measures. To focus educational campaigns, it is important to define high-risk populations, including subjects reporting multiple sexual partners. Along this line, it is important to identify the characteristics of women with promiscuous sexual habits. We therefore analysed the relationship between selected socio-demographic characteristics and lifestyle habits and the number of sexual partners and age at first intercourse among more than one thousand control women interviewed as part of a casecontrol study of cervical neoplasia conducted in the greater Milan area, rthern Italy. Materials and methods The subjects included in the present analysis were the control groups of a case control study on intra-epithelial and invasive cervical neoplasia conducted since 98 in the greater Milan area, rthern Italy. The general design of the investigation has already been described.6 7 Briefly, trained interviewers identified and questioned subjects admitted to the major general and university hospitals of the area under surveillance for acute, non gynaecological or urinary tract conditions or who were referred to cervical screening clinics on selected days (according to the interviewers and hospital schedule). Subjects admitted to hospital for diseases known or suspected to be related to sexual habits (such as sexually transmitted diseases) were not eligible for the study. The protocol indicated that all elegible subjects in the ward should be interviewed, but it is possible that some cases did not enter the study (for instance simply because they were not present in the ward at the time of the interviewers' visit). Interviewers, however, were not aware of the potential interest in the relation between sexual habits and any other information collected: thus it is unlikely that this selective mechanism may be cause of bias.

2 395 A total of 39 women aged -74 years (median age 54) were interviewed. Of those, % were admitted for traumatic conditions (mostly fractures and sprains), 9% for nontraumatic orthopaedic disorders (mostly low back pain and disc disorders), % for surgical conditions (mostly abdominal, such as appendicitis or strangulated hernia), 4% for other illnesses such as ear, nose, throat and dental disorders plus another 4% who were identified at cytological screening clinics and had a normal Pap smear. The structured questionnaire included information on socio-demographic variables and lifestyle habits, reproductive history, female hormone use and sexual history, which included questions on lifetime number of sexual partners and age at first intercourse. Participation was almost complete; despite the sensitive nature of the interview, less than 3% of the eligible subjects refused to participate. The present analysis is based on data collected before September 99. Table Distribution of 7* women according to reported number of sexual partners and selected characteristics. rthern Italy, Total Age (years) < <7 7- ) married married smokers smokers X - 3 l Miscarmages Induced abortions Barrer methods of contraception us K, (%/o) 98 (8) 36* (69) 5 (8) 5 (83) 7 (87) 55 (87) (86) (8) (73) (%)+ () 3 () 5 () 7 () (8) 7 () 55 () 36 ( ) (8) 4-5 (p = 4) 9 (7) 4 (9) 86 (83) 98 ().98 (p = ns) 643 (86) 6 (8) 75 (73) 5 (3) 6-94 (p = ) 45 (67) 6 ( ) 536 (84) 65 () 36 (9) (8) 4-8 (p = 4) 78 (8) 8 (9) 4 (83) () 5 (73) (5) (p = ns) 78 (8) ( ) 86 (8) 8 (7) 5 (76) 4 (6).5 (p = ns) 6 (85) 3 (9) 33 (8) 6 () 56 (8) 65 () -38 (p = ns) 768 (84) 86 (9) 5 (8) 6 (7).77 (p = ns) se 8 (4) 98 (33) 8 () 4 (3) -48 (p = ns) *Information on number of sexual partners was missing in cases. tdirectly standardised for age. *In some cases the sum does not add up to the total because of missing values.,3 (%) + 97 (9) 37 (9) 7 ( ) 6 (6) (5) 6 (3) 9 (4) Data analysis The percentages of women in strata of number of sexual partners and age at first intercourse according to selected variables were standardised for age by the direct method, using the whole study population as standard. Number of sexual partners and age at first intercourse were categorised in three levels to identify groups potentially characterised by different sexual habits. The number of sexual partners and age at first intercourse were compared among strata of various characteristics considered. The statistic described by Mantel was computed to test the existence of a linear trend between number of partners (or age at first intercourse) and the other covariates.8 This statistic is based on the calculation of observed and expected number of events and follows the chi square distribution with one degree of freedom. A similar analysis was performed for number of sexual partners in women aged 4 year or less. In order to allow for the potential reciprocal confounding effect of various factors significantly related to number of reported sexual partners in the age adjusted analyses, we included these factors in a multiple logistic regression model, fitted by the method of maximum likelihood9 to obtain relative frequency of number of sexual partners rates (odds ratios) and corresponding 95% approximate confidence intervals.' For this analysis subjects reporting two and three or more partners were compared in turn with subjects reporting one or no sexual partner. Included in the regression equations were terms for age, education, smoking habits and parity.. f,l\ (9) Results Table shows the distribution of study sub- 9 (8) jects according to number of sexual partners 68 (7) and selected characteristics. Overall, 8% of the study sample reported one sexual partner, 4 (6) % two and 9% three or more. The propor- 57 (4) tion of women reporting multiple sexual partners tended to decrease with age at interview 5 () (9% in subjects aged less than 35 years vs 3% 4 (6) in those aged more than 65) and was higher 6 () among more educated women (4% vs 9% of women with less than 7 and or more years 85 (9) of education reported three or more partners 9 (5) respectively). smokers reported three or more sexual partners more frequently (4%) than never 9 (4) smokers (6%). Furthermore the proportion of 3 (9) women reporting three or more sexual partners was higher among nulliparae, never married, 6 (6) and women with two or more induced abor- 5 (8) tions. The latter two findings were, however, 65 () statistically significant. relationship emerged between number of sexual partners 57 4 ( ) Pap smears and use of oral or barrier methods of contraception. Table presents the multi- 7 (4) variate odds ratios for variables significantly 5 (46) associated with number of partners in the ageadjusted analysis (education, smoking habits and parity) in relation to arbitrarily selected reference categories. These estimates should be

3 396 Table Multivariate odd ratios (and 95% confidence intervals) *for women reporting or > 3 sexual partners compared with those reporting only one partner in relation to selected characteristics. rthern Italy, <7 it it 7- - (-7--7) -9 ( -3 5) > - (-5--7) 4. (.-7.5) smokers it it smokers -8 (---8) -5 (-6-4-) it it - 7 (4-i) 3 (-5) 3 5 (3-.). ( -3) Maximum likelihood deviance (df) () (7) *Derived from logistic model including terms for age and the above listed variables. treference category. viewed in relative terms of comparison between various categories. The multivariate analysis confirmed the association between these factors and higher number of sexual partners. The analysis restricted to women aged 4 years or less (for a total of 34 subjects) is shown in table 3. As observed in the overall Table 3 Distribution of 34* women aged 4years or less according to reported number of sexual partners and selected characteristics. rthern Italy, 98-99, 3 (%o)+ (%) * (O%) Total 36 (73) 36 () 5 (6) < 7 77 (83) 8 (9) 8 (9) 7-89 (77) 4 () 3 ( ),, 7 (6) 4 () 3 (7) X 5-39 (p < -) married 4 (55) 9 () 4 (33) married 96 (78) 7 () 8 () Xl -7 (p < -) smokers 4 (8) 8 () 6 (9) smokers 94 (64) 8 () 36 (4) Xl 486 (p < ) 57 (54) 4 (3) 35 (33) - 45 (79) () 7 (9) >, 3 33 (97) (3) - (-) X 38- (p< -) Miscarriages (7) 3 ( ) 5 (8) l> 35 (85) 4 () (5) XA 358 (p = ns) Induced abortions 88 (73) 33 (3) 37 (4) 48 (73) 3 (5) 5 (3) -8 (p = ns) 59 (8) 5 (7) 9 () 37 (69) 6 ( ) () >, 4 (7) 5 (3) 3 (6) (p = ns) 4 (84) 4 (8) () 96 (64) (5) 3 () X, 8-4 (p<5) Barrier methods of contraception use 88 (75) 3 () 33 (3) 48 (67) 5 (7) 9 (6) X 4-44 (p = -4) *In some cases the sum does not add up to the total because of missing values. Parazzini, Cavalieri d'oro, Negri, Vecchia study population, ever smoking and nulliparity were associated with a higher number of sexual partners. married women and ever oral contraceptive or barrier methods of contraception users reported a higher number of sexual partners too. Furthermore, in the overall study population we have analysed the relation between age at first intercourse and the various factors considered (table 4). Overall, 5% of the study population reported first intercourse at age 8 or before, 34% between 9 and years, and 4% at age 3 or later.younger women (that is, more recent cohorts) more frequently reported early age at first intercourse and the proportion of never married women reporting first intercourse at age 8 or before was higher (5% vs % of never married vs married women). relationship emerged between age at first intercourse and smoking habits, education, parity, spontaneous or induced abortions, number of Pap smears and contraceptive habits. Discussion Before discussing the findings of this analysis, potential biases should be considered. The study population consisted of women in hospital for non-neoplastic, non-gynaecological and non-hormone-related conditions or referred to cervical screening clinics, interviewed as the control group in the framework of a casecontrol study of cervical neoplasms. They were matched by age with cases so they cannot be considered representative of the general population. Any inference, consequently, must be considered in strictly comparative terms. Since cervical neoplasia, is, to some extent, a sexually transmitted disease, the fact that about 5% of study population was included in the study group following a normal pap smear may introduce a bias; these subjects might be less "promiscuous" than general population. However, there was no marked difference in the results when the analysis was performed considering separately hospitalised subjects and the ones interviewed at the cervical screening clinics. Moreover, all subjects admitted to hospital for diseases known or suspected to be related to sexual habits were excluded from the study, and there is no clear evidence of women admitted to hospital for trauma or acute surgical conditions having sexual behaviour different from the general population. Thus, the estimates from this study should, at least in relative terms and in first approximation, provide reasonable indicators of sexual habits determinants of the rthern Italian population. Being drawn from a case-control study of cervical neoplasia, women who had undergone hysterectomy were excluded from the sample. From a hospital-based case-control study on breast and low genital tract neoplasms with a similar design conducted by our group in the greater Milan area," the prevalence of hysterectomised women was around %, that is, a minority of the population, and, again, there is no suggestion of these women having different

4 Table 4 Distribution of 39 women according to age at first intercourse and selected characteristics. rthern Italy, Total Age (years) < <7 7-,l X married married XA smokers smokers Xa Party -,3 Miscarriages, X Induced abordons l, XI Barrier methods of contraceptior Age at first intercourse (years) (8 (o/o) 87 (5) 99 (5) 58 () 47 (8) 46 (9) 37 () 34 (5) 98 (7) 55 () 9- (/o)+ 389 (34) (37) (4) (36) (33) (3) 98 (35) (36) 7 (3) -54 (p = ns),3 /)+ 463 (4) 37 (9) 9 (35) 6 (48) 5 (5) 84 (47) 48 (4) (37) 95 (5) 75 (5) 35 () 6 (7) () 354 (35) 437 (43) 3-85 (p = -) 67 (3) 53 (34) (9) 36 (35) -7 (p = ns) (39) () (7) (5) (3) (4) (4) (6) (4) (34) () (4) 59 (5) 7 (34) 3 (4) 4 (p = ns) 97 (33) 7 (4) (3) 4 (p = ns) 38 (34) 44 (37) 6 (39).54 (p = ns) 85 (7) 6 (39) 38 (35) -8 (p = ns) 6 (4) 37 (33) 8 () 8 (3) -36 (p = ns) a use 49 (6) 39 (34) 38 () 6 (35) -5 (p = ns) *Directiy standardised for age. tin some cases the sum does not add up to the total because of missing values. 334 (43) 9 (36) 68 (37) 95 (45) (33) 375 (4) 66 (36) (3) 44 (43) 35 (36) 4 () 8 (39) 6 (39) 68 (4) 49 (4) 54 (46) 4 6 (4) (44) sexual habits, although no formal evidence on the issue is available. Under-reporting of sexual partners cannot be excluded, particularly by older women. The hospital setting may conceivably reduce inaccuracy or bias in reporting sexual habits and other information, but the extent of this potential bias is still difficult to assess. Even assuming large-scale underreporting, however, this per se should not markedly influence internal comparison across strata of identified variables. Although age at first intercourse is not an optimal marker for late sexual behaviour, we decided to present also this indicator to provide information on sexual behaviour in early age, when less attention is generally paid toward safe sexual behaviours. The first evidence emerging from the study is the low absolute proportion of women reporting more than one sexual partner. Still, the inverse relationship between age at interview and number of sexual partners, and the direct one with age at first intercourse indicate 397 that sexual habits of the younger generations are changing. Similar results have been reported among English women and men.'3 An increasing number of sexual partners and a decreasing age at first intercourse in subsequent cohorts of women were observed in subjects interviewed as controls in a survey of risk factors for genitourinary cancers conducted on a similar Italian population.'4 In this study we observed an inverse relationship between education and number of sexual partners, but no relationship with age at first intercourse. This finding is inconsistent with the generally accepted opinion that lower social classes have a higher number of sexual partners. However, no social class trend in number of partners was observed in a study of sexual behaviour in women conducted in the UK though low social class was related to lower age at first intercourse.`5 Thus, important differences appear in the socio-cultural attitudes of various populations as regards the relationship between indicators of social class and sexual habits. Smoking was another characteristic of women reporting a higher number of sexual partners. In a public health perspective this suggests that the same group of women may be a target for different campaigns against smoking and for safer sex. In preventive terms, an important negative finding of this analysis is the lack of relation between contraceptive habits and number of sexual partners. Barrier methods are currently the most effective instruments to reduce the risk of heterosexual HIV infection. In Italy barrier methods of contraception are infrequentlly utilised in order to avoid unwanted pregnancies and probably only marginally to prevent sexually transmitted diseases.'6 In conclusion, this study indicates rather conservative sexual habits in most rthern Italian women (at least on the basis of selfreporting), but indicates that any educational campaigns towards safer sexual habits shbuld specifically aim at younger women, particularly the more educated, smokers, unmarried and nulliparae. This study was conducted within the framework of the "4 Progetto AIDS, 99". Ministero della Sanita-Istituto Superiore di Sanita, Roma, Italia. The generous contribution of Mrs Angela Marchegiano Borgomaineiro is gratefully acknowledged. The authors thank Ms Judy Baggott, Ivana Garimoldi and the G A Pfeiffer Memorial Library staff for editorial assistance. Luca Cavalieri d'oro is recipient of a fellowship from Instituto Superiore de Sanita, Roma, Italy. Skegg DCG. 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