| Literature DB >> 19307335 |
E Slaymaker1, J B Bwanika, I Kasamba, T Lutalo, D Maher, J Todd.
Abstract
OBJECTIVES: To derive the best possible estimates of trends in age at first sex (AFS) among successive cohorts of Ugandan men and women based on all the data available from the Demographic and Health Surveys (DHS) and cohort studies in Masaka and Rakai districts.Entities:
Mesh:
Year: 2009 PMID: 19307335 PMCID: PMC2654114 DOI: 10.1136/sti.2008.034009
Source DB: PubMed Journal: Sex Transm Infect ISSN: 1368-4973 Impact factor: 3.519
Number of male respondents by survey and year of birth, and median age at first sex (AFS) for each survey (for all DHS and for the Masaka and Rakai studies)
| Year of birth | DHS | Masakacohort | Rakaicohort | ||||||
| 1995 | 2001 | 2006 | Total | Median AFS† | N | Median AFS | N | Median AFS | |
| 1950–9 | 384 | 260 | 205 | 849 | 18.1 | 492 | 18.5 | 852 | 18.1 |
| 1960–9 | 636 | 494 | 502 | 1632 | 18.2 | 843 | 18.2 | 2060 | 17.9 |
| 1970–9 | 767 | 631 | 690 | 2088 | 18.0 | 1389 | 18.0 | 4060 | 17.8 |
| 1980–9 | 25 | 524 | 874 | 1423 | 17.9 | 2781 | 18.5 | 2821 | 17.1 |
| 1990–4 | 0 | 0 | 232* | 232* | 18.1* | 933 | 17.1 | 0 | – |
| Total | 1812 | 1909 | 2503 | 6224 | 18.0 | 6438 | 18.2 | 9793 | 17.7 |
DHS, Demographic and Health Survey.
*1990–1 only.
†Based on data from all surveys.
Number of female respondents by survey and year of birth, and median age at first sex (AFS) for each survey (for all DHS and for the Masaka and Rakai studies)
| Year of birth | DHS | Masakacohort | Rakaicohort | |||||||
| 1988 | 1995 | 2001 | 2006 | Total | Median AFS† | N | Median AFS | N | Median AFS | |
| 1950–9 | 1158 | 1171 | 777 | 360 | 3466 | 15.9 | 581 | 16.6 | 1039 | 15.9 |
| 1960–9 | 1948 | 2273 | 1604 | 1553 | 7378 | 16.1 | 1030 | 16.8 | 2196 | 16.0 |
| 1970–9 | 947 | 3199 | 2805 | 2497 | 9448 | 16.4 | 1768 | 17.0 | 5606 | 16.6 |
| 1980–9 | 0 | 131 | 2060 | 3366 | 5557 | 17.1 | 3235 | 17.5 | 4853 | 16.5 |
| 1990–94 | 0 | 0 | 0 | 755* | 755* | – | 829 | 16.9 | 0 | – |
| Total | 4053 | 6774 | 7246 | 8531 | 26604 | 16.4 | 7443 | 17.1 | 13694 | 16.4 |
DHS, Demographic and Health Survey.
*1990–1 only.
†Based on data from all surveys.
Figure 1Survival curves (cumulative proportion that has had sex by age) for men and women by 10-year birth cohorts. (A) Pooled Demographic and Health Survey data; (B) Masaka study; (C) Rakai study.
Crude hazard ratios (HRs) from Cox regression models showing the effect of 10-year birth cohorts on survival time to first sex (data from pooled DHS, Masaka study and Rakai study)
| Year of birth | DHS | Masaka | Rakai | |||
| Crude HR | p Value | Crude HR | p Value | Crude HR | p Value | |
| 1950–9 | 1 | 1 | 1 | |||
| 1960–9 | 1.08 (0.98 to 1.19) | 0.130 | 1.19 (1.06 to 1.33) | 0.004 | 1.03 (0.95 to 1.11) | 0.5 |
| 1970–9 | 1.08 (0.99 to 1.18) | 0.096 | 1.29 (1.15 to 1.44) | <0.001 | 1.05 (0.98 to 1.13) | 0.16 |
| 1980–9 | 0.93 (0.83 to 1.05) | 0.253 | 0.98 (0.87 to 1.11) | 0.79 | 1.61 (1.49 to 1.74) | <0.001 |
| 1990–4 | 0.86 (0.61 to 1.21) | 0.383 | 0.32 (0.19 to 0.64) | <0.001 | – | – |
| Total | 6113 | 5655 | 11211 | |||
| 1950–9 | 1 | 1 | 1 | |||
| 1960–9 | 0.94 (0.9 to 0.99) | 0.017 | 0.92 (0.83 to 1.02) | 0.11 | 0.96 (0.89 to 1.03) | 0.3 |
| 1970–9 | 0.87 (0.83 to 0.92) | <0.001 | 0.83 (0.75 to 0.91) | <0.001 | 0.81 (0.76 to 0.87) | <0.001 |
| 1980–9 | 0.67 (0.63 to 0.71) | <0.001 | 0.62 (0.57 to 0.69) | <0.001 | 1.03 (0.96 to 1.11) | 0.36 |
| 1990–4 | 0.37 (0.3 to 0.44) | <0.001 | 0.23 (0.15 to 0.35) | <0.001 | – | – |
| Total | 26531 | 6880 | 14808 | |||
DHS, Demographic and Health Survey.
Figure 2Survival curves (cumulative proportion who have had sex by age) for men and women born since 1970 by 5-year birth cohorts. (A) Pooled Demographic and Health Survey data; (B) Masaka study; (C) Rakai study.
Crude hazard ratios (HRs) from Cox regression models showing the effect of 5-year birth cohorts on survival time to first sex (data from pooled DHS, Masaka study and Rakai study)
| Year of birth | DHS | Masaka | Rakai | |||
| Crude HR | p Value | Crude HR | p Value | Crude HR | p Value | |
| 1970–4 | 1 | 1 | 1 | |||
| 1975–9 | 0.99 (0.89 to 1.1) | 0.81 | 1.02 (0.91 to 1.15) | 0.7 | 1.10 (1.03 to 1.17) | 0.002 |
| 1980–4 | 0.88 (0.77 to 1.0) | 0.059 | 0.94 (0.83 to 1.06) | 0.29 | 1.59 (1.49 to 1.71) | <0.001 |
| 1985–9 | 0.82 (0.70 to 0.96) | 0.011 | 0.51 (0.44 to 0.59) | <0.001 | 1.58 (1.42 to 1.76) | <0.001 |
| 1990–4 | 0.8 (0.57 to 1.12) | 0.187 | 0.21 (0.12 to 0.34) | <0.001 | – | – |
| Total | 3662 | 4398 | 8013 | |||
| 1970–4 | 1 | 1 | 1 | |||
| 1975–9 | 0.97 (0.92 to 1.03) | 0.301 | 0.93 (0.84 to 1.02) | 0.13 | 0.94 (0.89 to 0.99) | 0.016 |
| 1980–4 | 0.82 (0.77 to 0.86) | <0.001 | 0.84 (0.76 to 0.93) | 0.001 | 1.20 (1.13 to 1.26) | <0.001 |
| 1985–9 | 0.67 (0.62 to 0.73) | <0.001 | 0.54 (0.48 to 0.61) | <0.001 | 1.37 (1.27 to 1.49) | <0.001 |
| 1990–4 | 0.44 (0.37 to 0.54) | <0.001 | 0.27 (0.18 to 0.41) | <0.001 | – | – |
| Total | 15734 | 5328 | 11707 | |||
Restricted to those born on or after 1 January 1970.
DHS, Demographic and Health Survey.
Hazard ratios (HRs) from Cox regression models showing the effect of 5-year birth cohorts on survival time to first sex (for pooled DHS data), stratified for area of residence, region, education and wealth
| Median AFS 1970–4 cohort | HRs by birth cohort | |||||
| 1970–4 | 1975–9 | 1980–4 | 1985–9 | 1990–1 | ||
| All subjects (N) | 1002 | 1041 | 831 | 558 | 230 | |
| All subjects (HR) | 17.7 | 1 | 0.99 | 0.88 | 0.8 | |
| Area (urban/rural) | ||||||
| Urban | 17.1 | 1 | 0.48 | |||
| Rural | 17.9 | 1 | 1.04 | 0.91 | 0.85 | 0.88 |
| Region | ||||||
| Central† | 17.5 | 1 | 0.95 | 0.99 | 0.96 | 0.64 |
| Eastern | 17.0 | 1 | 0.97 | 0.82 | ||
| Northern | 18.2 | 1 | 1.22 | 0.95 | 1.14 | |
| Western | 18.0 | 1 | 0.90 | 0.8 | ||
| Education | ||||||
| None | 17.6 | 1 | 0.87 | 0.88 | 0.39 | N/A |
| Primary | 17.6 | 1 | 1.02 | 0.85 | 0.85 | 0.68 |
| Secondary and above | 18.1 | 1 | 0.97 | 0.97 | 0.84 | 1.71 |
| Wealth ranking | ||||||
| Poorest | 17.3 | 1 | 1.0 | 0.86 | 0.73 | 1.3 |
| Poor | 18.4 | 1 | 1.19 | 0.96 | 0.75 | |
| Middle | 17.7 | 1 | 0.82 | 0.93 | 0.84 | 0.71 |
| Rich | 15.7 | 1 | 0.82 | 0.79 | 0.73 | 0.93 |
| Richest | 16.2 | 1 | 0.87 | 1.0 | 0.75 | |
| Year of survey | ||||||
| 1995 | 17.5 | 1 | 0.92 | 0.51 | – | – |
| 2001 | 18.1 | 1 | 1.02 | 0.95 | 0.6 | – |
| 2006 | 17.6 | 1 | 0.97 | 0.9 | 0.85 | |
| All subjects (N) | 4893 | 4532 | 3454 | 2101 | 754 | |
| All subjects (HR) | 16.4 | 1 | 0.97 | |||
| Area (urban/rural) | ||||||
| Urban | 16.6 | 1 | 0.94 | |||
| Rural | 16.3 | 1 | 0.99 | |||
| Region | ||||||
| Central† | 16.1 | 1 | 0.97 | |||
| Eastern | 15.8 | 1 | 0.96 | |||
| Northern | 16.5 | 1 | 0.97 | |||
| Western | 17.0 | 1 | 0.96 | |||
| Education | ||||||
| None | 15.9 | 1 | 0.99 | 0.98 | 0.77 | 0.41 |
| Primary | 16.2 | 1 | 1.04 | |||
| Secondary and above | 17.9 | 1 | 0.92 | 0.94 | 0.87 | 0.91 |
| Wealth ranking | ||||||
| Poorest | 16.0 | 1 | 1.05 | 0.94 | 0.82 | 0.35 |
| Poor | 16.3 | 1 | 0.99 | 0.91 | ||
| Middle | 15.1 | 1 | 1.09 | |||
| Rich | 15.0 | 1 | 0.9 | |||
| Richest | 17.1 | 1 | 1 | 0.88 | 0.75 | |
| Year of survey | ||||||
| 1995 | 16.3 | 1 | 0.98 | 0.67 | ||
| 2001 | 16.6 | 1 | 1.04 | – | ||
| 2006 | 16.2 | 1 | 0.93 | |||
Restricted to those born on or after 1 January 1970.
All birth cohorts compared with those born in 1970–4.
*p<0.05; **p<0.01; ***p<0.001.
†Central region contains Masaka and Rakai districts.