CHAPTER 1.1 LITERATURE REVIEW AND OBJECTIVES
1.1.5 DISCONTINUATION PATTERNS
1.1.5.4 Temporary Discontinuation
More recently, a prospective study of 430 DMP A users was undertaken to determine factors influencing continuation rates (Hubacheret al,2000). The continuation rate at one year was 51%.Consistent with the findings above, providers were found to have an important influence on continuation rates, with women counselled to return to the clinic if they experienced side effects 2.7 times more likely to continue with the method.Those told that amenorrhoea might occur with injectable use were more than 2.5 times more likely to continue. Other factors found to be influential were number of children,attitudes towards menstruation,lactating on admission and spousal input on method choice.
Study Population
Paul et al (1997) report on a national population-based retrospective study of 1864 women in New Zealand. They submit that most studies undertaken on DMPA use have been among clinic attenders or women recruited into clinical trials,including the studies conducted by the WHO, and are therefore less likely to be representative ofDMPA users. In comparing DMPA continuation rates from their study with other studies, rates were found to be"as short or shorter". For instance, continuation rates at one year for first-time users was only 49% in the population-based New Zealand study,compared to 69% in the clinic-based Egypt study (Salemet al 1988).
discontinuations could be attributed to default,because return for a repeat injection occurred more than 16 weeks after the last dose. Itwas suggested that these women be regarded as"poorly compliant continuers" rather than discontinuers (Potteret al, 1997, p.310). This poor compliance behaviour was also reported to occur amongst IPC users in a Kenyan study (Sekadde-Kigonduetal,1996).A reason given for taking a break was to allow menstruation to recommence before returning for the next injection (Beksinskaet al,2001a; Department of Healthetal,2002). Beksinskaetal(2001a) reported further that some injectable users believed that they would not conceive as long as they were
amenorrhoeic. Periods of temporary discontinuation,referred to as nonuse segments (Beksinskaet al, 2001a), can lead to unintended pregnancy. Counselling about side effects and the need to adhere to the dosing regimen is advocated.
Conclusion
In general,discontinuation rates for IPCs were high. Study findings are conflicting and confusing and need to be interpreted cautiously. Discrepancies in overall discontinuation rates are found to be the rule rather than the exception. Cultural,religious and personal attitudes and provider influence are important determinants of individual response to menstrual disturbances (Fraser and Weisberg, 1981;Meade et al, 1984; Salem et al, 1988;
Dateyet al, 1995), and generalization of findings from discontinuation studies may not be appropriate. Poorly defined criteria for discontinuation and differences in study design and population also make comparison of discontinuation rates problematic. However, discontinuation based on experience of side effects,will not, with the possible exception of amenorrhoea,lead to greater improvement in continuation rates with one injectable product above another.
0'.w
Table 1.1.4 Summary of findings on discontinuation patterns from relevant studies
Study Notes Measure DMPA NET-EN 200mg"
(WHO=World Health Organization) 150mg* Regimen 1 Regimen 2 Regimen 3
1. Chinnatamby, 1971 N=515 N/A N/A N=520
(comparative study, Ceylon - now
Sri Lanka, N=1035) Discontinuation rates were not Discontinuation rate at 15 months ±15% ± 15%
broken down according to whether DMPA or NET-EN was used
2. Schwallie & Azenzo, 1973T N=3857
(Multi-centre,collaborative study, Continuation rates:
1965-1971, 54 investigators, at 12 months 59.4/100 Q
DMPA only, healthy women,55% at 24 months 41.5/100 Q
white,demonstrated fertility, at 36 months 30.2/l00Q
N=3857) at 48 months 24.1/100 2
3.WHO,1977T Chandigarh had an atypically N=846 N/A N/A N=832
(Randomised 10-centre high discontinuation rate for Cumulative discontin. Rates at one comparative trial, healthy,non- menstrual abnormalities with year:
breastfeeding women of both products which had a Amenorrhoea 1I.5/100Q 1.8/l00 Q
demonstrated fertility, N= 1678) pronounced effect on the difference significant
analysis of the pooled data Bleeding problems 9.3/100 Q 10.3/l00Q
Participating Centres: difference not significant
16.9/l00Q
Alexandria,Bahia-Salvador, All medical reasons 23.4/100 Q
Bangkok,Bombay, Chandigarh, difference significant
Ibadan,Ljubljana,Manila, Non-medical reasons 7.7/100Q 9.5/l00Q
Utrecht, Lima difference not significant
*Given every 12 weeks or every 90 days
#Regimen 1:Given every 56/60 days; Regimen 2:Given every 60 days or 8 weeks for six months and then every 12 weeks; Regimen 3: Given every 12 weeks
t Additional information about the study design obtained from Kaunitz (1992).
Table 1.1.4 Continued
Study Notes Measure DMPA NET-EN 200mg"
(WHO=World Health Organization) 150mg* Regimen 1 Regimen 2 Regimen 3
4. WHO, 1983T Considerable variation found N=1587 N=789 N-796 N/A
(2 year multi-national comparative between centres Total discontinuation rates:
randomized trial, 13 centres, at 1 year (no significant difference) 51.4/100~ 49.7/100~ 50.3/100~
healthy non-breastfeeding ~ at 2 years (no significant difference) 73.5/l00~ 70.7/100~ 72.4/100 ~
N=3172)
Discontinuation rates due to:
Participating Centres: Amenorrhoea
Alexandria,Bangkok,Ibadan, at one year (significant difference) 11.9/100~ 6.8/100~ 8.4/100 ~
Karachi,Lusaka, Manila,Mexico at two years (significant difference) 24.2/100 ~ 14.7/100~ 14.6/l00~
City,Salvador,Santiago, Bleeding problems
Ljubljana,Luxembourg,Milan, at 1 year (no significant difference) 15.0/100 ~ 13.6/100 ~ 13.7/100~
Utrecht at 2 years (no significant difference) 18.8/100 ~ 18.4/100~ 21.8/100 ~
Weight at 2 years
(no significant differencebetween DMPA 2.1/100~ 1.6/100 ~ O.8/100~
& NET-EN Regimen 1)
*Given every 12 weeks or every 90 days
#Regimen 1: Given every 56/60 days; Regimen 2:Given every 60 days or 8 weeks for six months and then every 12 weeks; Regimen 3: Given every 12 weeks t Additional information about the study design obtained from Kaunitz (1992).
0'\
VI
Table 1.1.4 Continued
Study Notes Measure DMPA NET-EN 200mg"
150mg* Regimen I Regimen 2 Regimen 3
5. Banerjee et al1984 N=1181 N=1207
(comparative clinical trial of two No statistical differences Total discontinuation rates:
dosage regimens of NET-EN, at 6 months 21.8/IOO~ 22.0/IOO ~
Indian~,16 Human Reproductive at 12 months 41.5/100 ~ 40.2/IOO ~
Research Centres,N=2388) at 18 months 56.9/IOO~ 55.5/l00~
at 24 months 68.6/IOO~ 67.4/100~
No statistical differences Discontinuation rates due to:
Amenorrhoea
at 6 months 1.6/l00~ 1.8/IOO~
at 12 months 7.6/100~ 6.9/IOO~
at 18 months 13.2/l00~ 12.7/100 ~
at 24 months 23.8/IOO~ 20.I1IOO~
No statistical differences Heavy&prolonged bleeding
at6 months 3.5/l00~ 3.2/100~
at 12 months 7.5/l00~ 6.5/l00~
at 18 months ll.I/IOO~ 1O.6/100 ~
at 24 months 15.6/l00~ I3.5/IOO~
No statistical differences Irregular bleeding
at 6 months 2.5/l00~ 4.0/100 ~
at 12 months 7.8/l00~ 7.5/100~
at 18 months 10.6/100~ I1.8/100~
at 24 months 12.1/100~ 16.4/100 2
*Given every 12 weeks or every 90 days
#Regimen I: Given every 56/60 days; Regimen 2: Given every 60 days or 8 weeks for six months and then every 12 weeks; Regimen 3: Given every 12 weeks.
Table 1.1.4 Continued
Study Notes Measure DMPA NET -EN 200mglt
(WHO=World Health Organization) 150mg* Regimen 1 Regimen 2 Regimen 3
6. Meadeet at,1984 Rates> WHO (1983,49.7),but N=5792
(prospective clinical field study, similar to the Mexico City Total discontinuation rates:
rural Mexico, N=5792) participating centre of the at 12 months 57.0/l00~
WHO study (53.1 at 12 at 18 months 69.0/100~
months)
Discontinuation rates due to:
Amenorrhoea 12.6/100~
at 12 months 14.3/100~
at 18 months Bleeding problems
at 12 months 8.0/100~
at 18 months 9.3/l00~
7. Rahmanet al,1985 Overall discontinuation rate N-913
(field study in 6 clinics NET-EN and reasons for discontin- Total cumulative discontin. rates:
onlyBangladesh, N=913) uation varied markedly at 6 months 26.3/l00~
between clinics, in spite of at 12 months 37.3/100 ~
similar participant age, parity, at 18 months 42.9/100~
residence and history of
contraceptive use. Discontinuation due to:
Heayy and/or prolonged bleeding
at 6 months 4.3/l00~
at 12 months 6.3/100~
at 18 months 6.7/100~
Irregular bleeding or spotting
at 6 months 2.8/l00~
at 12 months 3.9/100~
at 18 months 5.2/l00~
Amenorrhoea
at 6 months 2.8/100~
C\-...l
Table 1.1.4 Continued
Study Notes Measure DMPA NET-EN 200mgll
150mg* Regimen 1 Regimen2 Regimen 3
8. Salemet al, 1988 N=200 N=200
(randomized comparative study,
Egypt,N=400) DMPA users had better one- Continuation rates at one year 68.8/l00s;? 57.l/100s;?
year continuation rates
Cumulative discontin. rates due to:
More commonly experienced Amenorrhoea 10.6/100 s;? 13.0/l00s;?
by DMPA users,but higher Bleeding problems 8.l/100s;? 12.5/100 s;?
discontinuation with NET-EN
9. Beksinskaet al,2001a N=52 N=137
(prospective cohort study,South No difference in continuation Continuation rates:
Africa,urban clinic recruits, rates for DMPA and NET-EN at one year 42% 41%
n=189) at two years 21% 20%
*Given every 12 weeks or every 90 days
#Regimen 1:Given every 56/60 days;Regimen 2:Givenevery 60 days or 8 weeks for six months and then every 12 weeks; Regimen 3: Given every 12 weeks.