'Continuation rate', 'use-effectiveness' and their assessment for the diaphragm and jelly method

Abstract The application of the life-table technique in the calculation of use-effectiveness of a contraceptive was proposed by Potter in 1963.(1) The technique was also found to be useful in assessing the duration for which the use of a contraceptive was continued. The keen interest that existed in the use of IUD in the mid-1960's was reflected in the terminology developed for assessment of the continuity of use. 'Retention rate' was a frequently used index.(2) Because of the development of the concept of segments whose end-period determined either termination of the use of a method or its continuance on a cut-off date, 'closure rate' and 'termination rate' have been used as measures of the discontinuance of the use of methods primarily of the IUD.(3) While discussing concepts relating to acceptance, use and effectiveness of family planning methods, more generally, an expert group suggested that 'continuation' should be used to denote that a client (or a couple) had begun to practise a method and that the method was still being practised.(4) Since this group defined 'an acceptor' as a person taking service and/or advice, i.e. having an IUD insertion or a sterilization operation or receiving supplies (or advice on methods such as 'rhythm' or coitus-interruptus with the intent of using the method), the base for the assessment of continuation rates, according to this group, would be only those acceptors who had begun using the method. The lifetable method has also been used for the study of the continuation rate for pill acceptors.(5) Balakrishnan, et al., made a study of continuation rates of oral contraceptives using the multiple decrement life-table technique.(6).