Main Hypothesis:~The use of direct SMS without an explanatory call for cervical cancer screening invitation is an acceptable option to invite women if the participation obtained is more than 70% and not less than 15% of the call (current practice).~Specific Hypothesis:~Participation in cervical cancer screening programme using SMS invitation is non-inferior to 70%.~Participation in cervical cancer screening programme using telephone call is non-inferior to 70%.~Participation using SMS invitation is non-inferior to participation using telephone call invitation, considering that an absolute difference less than 15% may not be clinically relevant.~Sample size calculation:~A one-sample non-inferiority test for calculating sample size was performed, assuming a participation rate of 80% using SMS invitation and 85% using telephone call invitation in the cervical cancer screening programme. To detect a participation rate using SMS or telephone call invitation non-inferior to 70%, with a margin of 5%, accepting an alpha risk of 0.025 and a beta risk of 0.2, and 5% of loses of follow-up, we will need 27 women in the telephone call group and 59 women in the SMS group. To observe this non-inferiority by age group (≤40 years, 41-54 years, ≥55 years), 27 and 59 women will be needed for each age group.~To compare both study arms, a two-sample non-inferiority test was performed assuming that using SMS messages to invite women to participate in cervical cancer screening programme will be 5% lower compared to participation when invitation is performed by a phone call (80% versus 85% respectively), although this difference will be non-inferior to 15-15.5%. Thus, if there is a true difference in favor of the telephone call group of 5%, assuming 5% of loses of follow-up, then 450 women will be required (225 in each arm) to be 80% sure that the upper limit of a one-sided 97.5% confidence interval will exclude a difference in favor of the SMS group of more than 15-15.5%.~Randomization procedure:~Women will be randomized in two study arms: intervention (SMS message invitation) and control (telephone call invitation). Randomization will be performed based on permuted blocks of 6 women to ensure equal distribution among age groups.
A study on two different methods of invitation to participate to the cervical cancer screening programme will be conducted within a demonstration project to switch from cytology-based screening to HPV-based screening using self-sampling delivered through the network of pharmacy offices among regular screening attendants in the Barcelona Metropolitana Sud Area, in Catalonia.~At the moment, eligible women are invited to participate to cervical cancer screening via a telephone call invitation explaining the new self-sampling method. Invitation via SMS containing a link to a webpage with information on most frequent questions might be an adequate alternative method that would save costs and workload on human resources.~The aim of this study is to assess the impact on cervical cancer screening participation of an invitation method based on text messaging (SMS).~The invitation method will be evaluated through an interventional trial, in which we will compare the invitation to cervical cancer screening using SMS versus a telephone call invitation explaining the new self-sampling method.