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Biomedical subjects

A J Copas

Publications and source records attributed to A J Copas.

28 records · Page 2Linked to original sources
PubMed2001

Africans in London continue to present with advanced HIV disease in the era of highly active antiretroviral therapy.

Our findings show that despite the numerous advances in the management of HIV disease, this has not resulted in earlier presentation in Africans or non-Africans. African patients are still presenting with significantly more advanced disease than non-Africans, and are more likely to have AIDS at presentation in 1998-1999 than in 1982-1995. An urgent need exists to identify the factors associated with delayed presentation, both to optimize clinical outcomes and reduce the possibility of onward transmission.

Adult↗
PubMed2001

Sexual behaviour in Britain: partnerships, practices, and HIV risk behaviours.

BACKGROUND: Sexual behaviour is a major determinant of sexual and reproductive health. We did a National Survey of Sexual Attitudes and Lifestyles (Natsal 2000) in 1999-2001 to provide population estimates of behaviour patterns and to compare them with estimates from 1990-91 (Natsal 1990). METHODS: We did a probability sample survey of men and women aged 16-44 years who were resident in Britain, using computer-assisted interviews. Results were compared with data from respondents in Natsal 1990. FINDINGS: We interviewed 11161 respondents (4762 men, 6399 women). Patterns of heterosexual and homosexual partnership varied substantially by age, residence in Greater London, and marital status. In the past 5 years, mean numbers of heterosexual partners were 3.8 (SD 8.2) for men, and 2.4 (SD 4.6) for women; 2.6% (95% CI 2.2-3.1) of both men and women reported homosexual partnerships; and 4.3% (95% CI 3.7-5.0) of men reported paying for sex. In the past year, mean number of new partners varied from 2.04 (SD 8.4) for single men aged 25-34 years to 0.05 (SD 0.3) for married women aged 35-44 years. Prevalence of many reported behaviours had risen compared with data from Natsal 1990. Benefits of greater condom use were offset by increases in reported partners. Changes between surveys were generally greater for women than men and for respondents outside London. INTERPRETATION: Our study provides updated estimates of sexual behaviour patterns. The increased reporting of risky sexual behaviours is consistent with changing cohabitation patterns and rising incidence of sexually transmitted infections. Observed differences between Natsal 1990 and Natsal 2000 are likely to result from a combination of true change and greater willingness to report sensitive behaviours in Natsal 2000 due to improved survey methodology and more tolerant social attitudes.

Adolescent↗
PubMed2001

Sexual behaviour in Britain: early heterosexual experience.

BACKGROUND: Relatively high rates of teenage conception and sexually transmitted infection among young people in Britain have focused attention on early sexual behaviour and its determinants. We report the results of the second National Survey of Sexual Attitudes and Lifestyles (Natsal 2000). METHODS: We did a probability sample survey between 1999 and 2001, of men and women aged 16-44 years in Britain. Participants were interviewed using a combination of computer-assisted face-to-face and self-completion questionnaires, and asked questions regarding first heterosexual intercourse, communication about sex, pregnancy, and sexually transmitted infections (STIs). FINDINGS: We recruited 11161 men and women to the survey (4762 men, 6399 women). The proportion of those aged 16-19 years at interview reporting first heterosexual intercourse at younger than 16 years was 30% for men and 26% for women; median age was 16 years. The proportion of women reporting first intercourse before 16 years increased up to, but not after, the mid-1990s. There has been a sustained increase in condom use and a decline in the proportion of men and women reporting no contraceptive use at first intercourse with decreasing age at interview. Among 16-24 year olds, non-use of contraception increased with declining age at first intercourse; reported by 18% of men and 22% of women aged 13-14 years at occurrence. Early age at first intercourse was significantly associated with pregnancy under 18 years, but not with occurrence of STIs. Low educational attainment was associated with motherhood before 18 years, but not abortion. INTERPRETATION: The increase in the proportion of women reporting first intercourse before age 16 years does not appear to have continued throughout the past decade. Only a small minority of teenagers have unprotected first intercourse, and early motherhood is more strongly associated with educational level than with family background. Factors most strongly associated with risk behaviour and adverse outcomes have considerable potential for preventive intervention.

Adolescent↗
PubMed2001

Sexual behaviour in Britain: reported sexually transmitted infections and prevalent genital Chlamydia trachomatis infection.

BACKGROUND: Studies of the epidemiology of sexually transmitted infections (STI) are largely based on surveillance data. As part of a national survey of sexual attitudes and lifestyles (Natsal 2000) in Britain, we estimated the frequency of self-reported STIs, and the prevalence of urinary Chlamydia trachomatis infection. METHODS: We did a stratified probability sample survey of 11161 men and women aged 16-44 years in Britain. Computer assisted self-interviews contained items on the nature and timing of previously diagnosed STIs. Half of all sexually experienced respondents aged 18-44 years were invited to provide a urine sample for ligase chain reaction testing for C trachomatis infection. FINDINGS: 10.8% of men and 12.6% of women reported ever having an STI, 3.6% of men and 4.1% of women reported ever being diagnosed with genital warts, and 1.4% of men and 3.1% of women reported previous infection with C trachomatis. 76% of men and 57% of women ever diagnosed with an STI had been to a GUM clinic. C trachomatis was found in 2.2% (95% CI 1.5-3.2) of men and 1.5% (95% CI 1.11-2.14) of women with age-specific prevalence being highest among men aged 25-34 (3.1%) and women aged 16-24 years (3.0%). Non-married status, age, and reporting partner concurrency or two or more sexual partners in the past year were independently associated with infection with C trachomatis. INTERPRETATION: We show substantial heterogeneity in distribution of reported STIs, and the demographic and behavioural determinants of prevalent genital chlamydial infection. The results have potentially wide application for proposed chlamydia screening programmes which, given the demonstrated prevalence, must now proactively seek to involve men.

Adolescent↗
PubMed2001

A cognitive behavioural intervention to reduce sexually transmitted infections among gay men: randomised trial.

OBJECTIVE: To determine the effectiveness of a brief cognitive behavioural intervention in reducing the incidence of sexually transmitted infections among gay men. DESIGN: Randomised controlled trial with 12 months' follow up. SETTING: Sexual health clinic in London. PARTICIPANTS: 343 gay men with an acute sexually transmitted infection or who reported having had unprotected anal intercourse in the past year. MAIN OUTCOME MEASURES: Number of new sexually transmitted infections diagnosed during follow up and self reported incidence of unprotected anal intercourse. RESULTS: 72% (361/499) of men invited to enter the study did so. 90% (308/343) of participants returned at least one follow up questionnaire or re-attended the clinic and requested a check up for sexually transmitted infections during follow up. At baseline, 37% (63/172) of the intervention group and 30% (50/166) of the control group reported having had unprotected anal intercourse in the past month. At 12 months, the proportions were 27% (31/114) and 32% ( 39/124) respectively (P=0.56). However, 31% (38/123) of the intervention group and 21% (35/168) of controls had had at least one new infection diagnosed at the clinic (adjusted odds ratio 1.66, 95% confidence interval 1.00 to 2.74). Considering only men who requested a check up for sexually transmitted infections, the proportion diagnosed with a new infection was 58% (53/91) for men in the intervention group and 43% (35/81) for men in the control group (adjusted odds ratio 1.84, 0.99 to 3.40). Using a regional database that includes information from 23 sexual health clinics in London, we determined that few participants had attended other sexual health clinics. CONCLUSIONS: This behavioural intervention was acceptable and feasible to deliver, but it did not reduce the risk of acquiring a new sexually transmitted infection among these gay men at high risk. Even carefully designed interventions should not be assumed to bring benefit. It is important to evaluate their effects in randomised trials with objective clinical end points.

Adolescent↗
PubMed2001

Effect of computer-assisted self-interviews on reporting of sexual HIV risk behaviours in a general population sample: a methodological experiment.

OBJECTIVES: To develop methods to maximize the accuracy of reporting HIV risk behaviours in a general population survey. We assessed the feasibility of using a computer-assisted self-completion interview (CASI) in comparison with pen-and-paper self-completion interview (PAPI). DESIGN: A probability sample survey of residents aged 16-44 years in Britain, with alternate assignment of addresses to interview by CASI (462) or PAPI (439). METHODS: Personal interviews exploring demographic and sexual behaviour variables. Principal outcome measures were the impact of CASI in relation to PAPI on data quality and rates of reporting a range of behaviours. RESULTS: A total of 901 interviews were completed; 829 individuals were eligible for and accepted the self-completion module. Internal consistency of data items was greater with CASI than PAPI and item non-response was lower. Overall, there was no significant difference in rates of reporting between CASI and PAPI. The main effect for CASI compared with PAPI in a generalized estimating equation (GEE) analysis was an OR (95% CI) of 1.04 (0.92-1.17). Variables were also examined individually, including homosexual partnership (adjusted OR 1.26 95%, CI 0.69-2.29), payment for sex (adjusted OR 0.68 95% CI 0.29-1.59), masturbation (adjusted OR 0.89 95% CI 0.66 1.22) and five or more partners in the past 5 years (OR 0.85 95% CI 0.61 -1.19). CONCLUSION: We found no evidence of a consistent effect of CASI on rates of reporting sexual HIV risk behaviours in this sample. CASI resulted in improvement in internal consistency and a reduction in missed questions.

Adolescent↗
PubMed2001

Incorporating retrospective data into an analysis of time to illness.

For studies of time to illness, the prospective cohort study is, in general, the method of choice. When the time of origin is known for all subjects, then a prevalent cohort study in which individuals are recruited at variable times after the start of the illness process is a suitable alternative. Often, when a prevalent cohort is being formed, data may also be available on individuals who are already ill but are alive. The incorporation of such data, which is practically appealing to many researchers, is discussed. The nature of the required assumptions and the need also to model the illness to death process are illustrated. Full likelihood and pseudolikelihood techniques are outlined and compared with each other and with the use of only prevalent cohort data in a small simulation study. An example based on an HIV seroconverter study is discussed for illustration. The full likelihood method is seen to be too complex for general application. The use of pseudolikelihoods is easier to implement. If there is reliable information on initiating event times and recruitment strategies are well defined, then the incorporation of retrospective data may be beneficial. In other situations, their incorporation is too problematic to be recommended.*To whom correspondence should be addressed.

Journal Article↗
PubMed1998

Psychological factors associated with recurrent vaginal candidiasis: a preliminary study.

OBJECTIVE: To identify psychological factors associated with chronic recurrent vaginal candidiasis. DESIGN: A cross sectional exploratory study of women with chronic, recurrent vaginal candidiasis. PATIENTS: 28 women found culture positive and treated for vaginal candidiasis by a clinic physician at least twice within the past 6 months. All women reported that they had experienced vaginal thrush six or more times within 1 year. A comparison group comprised 16 women with no history of recurrent vaginal candidiasis, of similar age range, and recruited from a women's family planning service. METHODS: Both groups were compared on demographic criteria, sexual health histories, mental health, and psychological health characteristics. A purpose designed structured interview was administered alongside a battery of standardised psychometric instruments measuring mood, satisfaction with life, self esteem, and perceived stress. RESULTS: The two groups showed considerable similarities, with no significant differences in demographic characteristics and most sexual health issues. However, women with recurrent vaginal candidiasis were significantly more likely to suffer clinical depression, to be less satisfied with life, to have poorer self esteem, and to perceive their lives as more stressful. Additionally, women with recurrent vaginal candidiasis reported that their candidiasis seriously interfered with their sexual and emotional relationships. CONCLUSIONS: Overall, this study identified many areas of psychological morbidity associated with chronic vaginal candidiasis, and indicates that development of appropriate psychological treatment initiatives in this area is long overdue.

Adult↗
PubMed1997

Assessing participation bias in a sexual behaviour survey: implications for measuring HIV risk.

OBJECTIVES: To assess the likelihood of participation bias in a large population-based sex survey, and its possible effect on estimates of HIV risk behaviours. DESIGN: Construction of general hypotheses about non-participants through comparisons of willing and unwilling participants. METHODS: British adults aged 16-59 years were surveyed in 1990-1991. Interviews consisted of a face-to-face section combined with a self-completion booklet (n = 18876). Interviewers recorded interviewee embarrassment. Homosexual experience and number of lifetime heterosexual partners (grouped 0, 1, 2 or more) were recorded prior to booklet offer. Logistic regression was performed, with embarrassment and booklet refusal as outcome variables, assessing their association with sexual behaviour after controlling for demographic variables. Assuming that, in sexual behaviour, non-participants are closer to the embarrased and the booklet refusers ('unwilling' participants) than to others, these analyses provide an indication of the nature of participation bias. RESULTS: Higher refusal an embarrassment rates were associated with both reporting no homosexual experience and fewer heterosexual partners. CONCLUSIONS: Under our untestable assumption, these results are consistent with non-participants being generally at lower risk of HIV infection. Methods need to be developed both to reduce participation bias in sex surveys, and to incorporate it in analysis.

Adolescent↗