Identifying women with cervical neoplasia: using human papillomavirus DNA testing for equivocal Papanicolaou results

CONTEXT: A Papanicolaou (Pap) test result of atypical squamous cells of undetermined significance (ASCUS) presents a clinical challenge. Only 5% to 10% of women with ASCUS harbor serious cervical disease, but more than one third of the high-grade squamous intraepithelial lesions (HSILs) in screening populations are identified from ASCUS Pap test results. OBJECTIVE: To determine whether human papillomavirus (HPV) DNA testing of residual material from liquid-based Pap tests and referral of cases found to be HPV-positive directly to colposcopy could provide sensitive detection of underlying HSILs in women with ASCUS Pap results, compared with repeat Pap testing. DESIGN AND SETTING: Natural history of women with ASCUS Pap smear results, all of whom had liquid-based cytology, HPV testing, and subsequent repeat Pap tests and colposcopy with histologic evaluation, conducted at 12 gynecology clinics in a large managed care organization between October 1995 and June 1996. PARTICIPANTS: From a cohort of 46009 women who had routine cervical examinations, 995 women with Pap test results of ASCUS who consented to participate were identified. MAIN OUTCOME MEASURES: Cervical histology, HPV test results, and repeat Pap smear results, and sensitivity of HPV testing to identify patients found to have HSIL+ histology. RESULTS: Of 995 participants with ASCUS Pap test results, 973 had both a definitive histologic diagnosis and HPV result. Sixty-five (6.7%) had histologic HSIL or cancer. For women with histologic HSIL+, the HPV test was positive in 89.2% (95% confidence interval [CI], 78.4%-95.2%), and the specificity was 64.1 % (95% CI, 60.9%-67.2%). The repeat Pap smear result was abnormal in 76.2% (95% CI, 63.5%-85.7%). Triage based on HPV testing only or on repeat Pap testing only would refer similar proportions (approximately 39%) to colposcopy. The sensitivity of HPV DNA testing for HSIL was equivalent to, if not greater than, that of the repeat Pap test. We further estimated that an HPV-based algorithm including the immediate colposcopy of HPV-positive women, and then repeat Pap testing of all others, would provide an overall sensitivity of 96.9% (95% CI, 88.3%-99.5%). CONCLUSIONS: For women with ASCUS Pap tests, HPV DNA testing of residual specimens collected for routine cervical cytology can help identify those who have underlying HSIL. By testing the specimen collected at initial screening, the majority of high-risk cases can be identified and referred for colposcopy based on a single screening.     

Stage at diagnosis and cancer survival for Indigenous Australians in the Northern Territory

OBJECTIVE: To investigate whether Indigenous Australians with cancer have more advanced disease at diagnosis than other Australians, and whether late diagnosis explains lower Indigenous cancer survival rates. DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: Indigenous and non-Indigenous people diagnosed with cancers of the colon and rectum, lung, breast or cervix and non-Hodgkin lymphoma in the Northern Territory of Australia in 1991-2000. MAIN OUTCOME MEASURES: SEER summary stage of cancer at diagnosis (local, regional or distant spread), cause-specific cancer survival rates and relative risk of cancer death. RESULTS: Diagnosis with advanced disease (regional or distant spread) was more common for Indigenous people (70%; 95% CI, 62%-78%) than for non-Indigenous people (51%; 95% CI, 53%-59%) with cancers of the colon and rectum, breast, cervix and non-Hodgkin lymphoma, but for lung cancer the opposite was found (Indigenous, 56% [95% CI, 46%-65%] v non-Indigenous, 69% [95% CI, 64%-75%]). Stage-adjusted survival rates were lower for Indigenous people for each cancer site. With few exceptions, the relative risk of cancer death was higher for Indigenous people for each category of stage at diagnosis for each cancer site. CONCLUSIONS: Health services apparently could, and should, be performing better for Indigenous people with cancer in the Northern Territory, and probably elsewhere in Australia. This study has demonstrated that data from cancer registers, enhanced with data on stage at diagnosis, can be used to monitor health service performance for Indigenous Australians in the Northern Territory; similar data is available in other States, and could be used to monitor health service performance for Indigenous people throughout Australia.     

Screening for Chlamydia trachomatis at the time of routine Pap smear in general practice: a cluster randomised controlled trial

OBJECTIVE: To determine whether asking general practitioners to offer chlamydia screening at the same time as Pap screening increases chlamydia screening rates. DESIGN: A pragmatic cluster randomised controlled trial. PARTICIPANTS AND SETTING: Doctors from 31 general practices in the Australian Capital Territory performing more than 15 Pap smear screens per year, and all women aged 16-39 years attending those practitioners between 1 November 2004 and 31 October 2005. INTERVENTION: Doctors in the intervention practices were asked to routinely offer combined chlamydia and Pap screening to eligible women; doctors in the control practices were asked to implement screening guidelines based on a risk assessment of the individual patient (ie, usual practice). MAIN OUTCOME MEASURE: Chlamydia screening rate per visit. RESULTS: There were 26 876 visits by eligible women during the study period: 16 082 to intervention practices and 10 794 to control practices. Chlamydia screening occurred during 6.9% (95% CI, 6.5%-7.3%) of visits to intervention practices and 4.5% (95% CI, 4.1%-4.9%) of visits to control practices. After controlling for clustering and potential confounders, there were twofold greater odds of chlamydia screening occurring during a visit by an eligible woman to an intervention practice than to a control practice (adjusted odds ratio, 2.1 [95% CI, 1.3-3.4]). CONCLUSION: Combining chlamydia and Pap screening increases the rate of chlamydia screening in general practice. Implementing this approach would require little additional infrastructure support in settings where a cervical screening program already exists.     

Treatment patterns for cancer in Western Australia: does being Indigenous make a difference?

OBJECTIVE: To examine whether hospital patients with cancer who were identified as Indigenous were as likely to receive surgery for the cancer as non-Indigenous patients. DESIGN, SETTING AND PATIENTS: Epidemiological survey of all Western Australian (WA) patients who had a cancer registration in the state-based WA Record Linkage Project that mentioned cancer of the breast (1982-2000) or cancer of the lung or prostate (1982-2001). MAIN OUTCOME MEASURES: The likelihoods of receiving breast-conserving surgery or mastectomy for breast cancer, lung surgery for lung cancer, or radical or non-radical prostatectomy for prostate cancer were compared between the Indigenous and non-Indigenous populations using adjusted logistic regression analyses. RESULTS: Indigenous people were less likely to receive surgery for their lung cancer (odds ratio [OR], 0.64; 95% CI, 0.41-0.98). Indigenous men were as likely as non-Indigenous men to receive non-radical prostatectomy (OR, 0.69; 95% CI, 0.40-1.17); only one Indigenous man out of 64 received radical prostatectomy. Indigenous women were as likely as non-Indigenous women to undergo breast-conserving surgery (OR, 0.86; 95% CI, 0.60-1.21). CONCLUSIONS: These results indicate a different pattern of surgical care for Indigenous patients in relation to lung and prostate, but not breast, cancer. Reasons for these disparities, such as treatment choice and barriers to care, require further investigation.     

The positive experience of screening quality among users of a cervical cancer detection center

BACKGROUND: Our objective was to determine the main factors associated with increased utilization of a cervical cancer screening program (CCSP) in a population with a high mortality rate due to cervical cancer. METHODS: A population-based study was carried out in the Mexican state of Morelos, Mexico. The study population included 3,197 women between the ages of 15 and 49 years who were selected at random using a State Household Sampling Framework in the State of Morelos's 33 municipalities. The sample included 2,094 women with a history of a previous Papanicolaou (Pap) test. RESULTS: A previous experience of good screening quality is strongly associated with greater use of the CCSP (OR = 4.2; 95% confidence interval [CI], 1.6-10.9). The educational level of the head of the family is related to more frequent use of Pap smear services. Women whose husbands have 13 or more years of education (OR = 1.8; 95% CI 1.1-2.9) were more likely to have been screened. Similarly, women who had used two or more family planning methods (OR = 1.6; 95% CI 1.2-2.1) and those who knew why the Pap test was given (OR = 3.0; 95% CI 2.1-4.3) had a better history of Pap screening. CONCLUSIONS: In areas where coverage of cervical cancer screening is low, a CCSP that guarantees the quality of all the different elements of care is essential if obstacles to cervical cancer prevention are to be eliminated. It is of particular importance to take into account and satisfy the perceptions and expectations of the women at risk.     

Fulfilling prophecy? Sexually transmitted infections and HIV in Indigenous people in Western Australia

OBJECTIVE: To compare trends and rates of HIV and sexually transmitted infections in Indigenous and non-Indigenous people of Western Australia. DESIGN AND SETTING: Analysis of WA notification data for chlamydia, gonorrhoea, and primary and secondary syphilis in 2002, and for HIV infections from 1983 to 2002. MAIN OUTCOME MEASURES: Rates of HIV and sexually transmitted infection by Indigenous status. RESULTS: In 2002, there were 3046 notifications for chlamydia, 1380 for gonorrhoea and 64 for syphilis. When information on Indigenous status was available, Indigenous people accounted for 41% of chlamydia and 76% of gonorrhoea notifications, with Indigenous:non-Indigenous age-standardised rate ratios of 16 (95% CI, 14-17) and 77 (95% CI, 67-88), respectively. Indigenous people accounted for 90.6% of syphilis notifications (age-standardised Indigenous:non-Indigenous rate ratio, 242 [95% CI, 104-561]). From 1985 to 2002, HIV notification rates for non-Indigenous people in WA declined and rates for Indigenous people increased. From 1994 to 2002, there were 421 notifications of HIV infection in WA residents, 52 (12.4%) in Indigenous people and 369 (87.6%) in non-Indigenous people. Indigenous people accounted for 39% and 6.2% of all notifications in WA females and males, respectively. The Indigenous:non-Indigenous rate ratios were 18 (95% CI, 12-29) for females and 2 (95% CI, 1-3) for males. CONCLUSIONS: Indigenous Western Australians are at greater risk of HIV transmission than non-Indigenous people. Strategies to prevent further HIV infection in Indigenous Australians should include control of sexually transmitted infections.     

Hospitalisation for head injury due to assault among Indigenous and non-Indigenous Australians, July 1999--June 2005

OBJECTIVE: To describe rates of hospitalisation for head injury due to assault among Indigenous and non-Indigenous Australians. DESIGN, SETTING AND PARTICIPANTS: Secondary analysis of routinely collected hospital morbidity data for 42,874 inpatients at public and private hospitals in Queensland, Western Australia, South Australia and the Northern Territory for the 6-year period 1 July 1999--30 June 2005. MAIN OUTCOME MEASURES: Rates per 100,000 population of head injury due to assault by Indigenous status, age, sex and location of residence. RESULTS: The overall rate of head injury due to assault was 60.4 per 100,000 population (95% CI, 59.8-60.9). The rate among the Indigenous population was 854.8 per 100,000 (95% CI, 841.0-868.9), 21 times that among the non-Indigenous population (40.7 per 100,000; 95% CI, 40.2-41.2). Most Indigenous (88%) and non-Indigenous (83%) victims of head injury due to assault were aged between 15 and 44 years. The peak incidence among the Indigenous population was in the 30-34-year age group, whereas that among the non-Indigenous population was in the 20-24-year age group. Indigenous females experienced 69 times the injury rate experienced by non-Indigenous females. CONCLUSIONS: Indigenous people, particularly women, were disproportionately represented among those hospitalised for head injury due to assault. Head injury imposes a substantial burden of care on individuals and communities. Along with the costs of treating head injury, these are good reasons to strengthen efforts to prevent head injury generally, with special attention to high-risk population segments.     

Racial disparities in infection-related mortality at Alice Springs Hospital, Central Australia, 2000--2005

OBJECTIVE: To compare infection-related mortality rates and pathogens isolated for Indigenous and non-Indigenous adult patients at Alice Springs Hospital (ASH). DESIGN, PARTICIPANTS AND SETTING: Retrospective study of inhospital deaths of adults (patients aged > or = 15 years) associated with an infection during a medical or renal admission to ASH between 1 January 2000 and 31 December 2005. MAIN OUTCOME MEASURES: Admission- and population-based infection-related mortality rates and mortality rate ratios (MRRs) for Indigenous versus non-Indigenous adults. RESULTS: There were 513 deaths, of 351 Indigenous and 162 non-Indigenous patients. For Indigenous patients, 60% of deaths were infection-related, compared with 25% for non-Indigenous patients (P < 0.001). The admission-based infection-related MRR for Indigenous versus non-Indigenous adults was 2.2 (95% CI, 1.6-3.1) (15.3 v 6.8 deaths per 1000 admissions; P < 0.001). After adjusting for age and year of death, the population-based infection-related MRR was 11.3 (95% CI, 8.0-15.8) overall (351 v 35 deaths per 100,000 population; P < 0.001) and 31.5 (95% CI, 16.1-61.8) for patients aged < 60 years. The median age of patients who died with an infection was 49 (interquartile range [IQR], 38-67) years for Indigenous and 73 (IQR, 58-80) years for non-Indigenous patients (P < 0.001). For Indigenous patients, 56% of infection-related deaths were associated with bacterial sepsis, with half of these due to enteric organisms. Other deaths followed chronic hepatitis B infection, invasive fungal infections and complications of strongyloidiasis. CONCLUSION: Indigenous patients at ASH are 11 times more likely than non-Indigenous patients to die with an infectious disease. This racial disparity reflects the ongoing socioeconomic disadvantage experienced by Indigenous Australians.     

Causes of inequality in life expectancy between Indigenous and non-Indigenous people in the Northern Territory, 1981-2000: a decomposition analysis

OBJECTIVE: To identify the causes of the gap in life expectancy between Indigenous and non-Indigenous populations of the Northern Territory and how the causes have evolved over time. DESIGN AND SETTING: Analysis of NT death data over four 5-year periods, 1 January 1981 to 31 December 2000 inclusive. A decomposition method using discrete approximations (Vaupel and Romo) was applied to abridged life tables for the Indigenous and non-Indigenous populations of the NT. MAIN OUTCOME MEASURES: Contribution of causes of death, grouped according to global burden of disease groups and categories, to the life expectancy gap. RESULTS: The gap between the life expectancy of Indigenous and non-Indigenous people in the NT did not appear to narrow over time, but there was a marked shift in the causes of the gap. In terms of disease groups, the contribution of communicable diseases, maternal, perinatal and nutritional conditions halved during the 20 years to 2000. Meanwhile, the contribution of non-communicable diseases and conditions increased markedly. The contribution of injuries remained static. In terms of disease categories, the contribution of infectious diseases, respiratory infections and respiratory diseases declined considerably; however, these gains were offset by significantly larger increases in the contribution of cardiovascular diseases and diabetes for Indigenous women and cardiovascular diseases, cancers and digestive diseases for Indigenous men. CONCLUSIONS: The main contributors to the gap in life expectancy between the Indigenous and non-Indigenous populations were non-communicable diseases and conditions, which are more prevalent in ageing populations. With the life expectancy of Indigenous people in the NT expected to improve, it is important that public health initiatives remain focused on preventing and managing chronic diseases.     

Prevalence of Helicobacter pylori in Indigenous Western Australians: comparison between urban and remote rural populations

OBJECTIVES: To determine and compare the prevalence of Helicobacter pylori in an urban and a remote rural Western Australian Indigenous community. DESIGN: Cross-sectional study of Helicobacter pylori status determined by urea breath tests between mid-January 2003 and the end of June 2004. PARTICIPANTS: 520 self-selected fasting participants, comprising 270 members of the Martu community at Jigalong, Punmu and Parnngurr in the East Pilbara region (129 men, 141 women; age range, 2-90 years) and 250 people from the Perth Indigenous community (96 men, 154 women; age range, 3-75 years. RESULTS: The overall prevalence of H. pylori was 76%, but the prevalence in the remote rural community was 91%, compared with 60% in the urban community. The odds of having H. pylori were six times greater for rural than for urban participants (odds ratio [OR], 6.34; 95% CI, 3.89-10.33). Further, the overall odds of H. pylori infection in males (rural and urban combined) were greater than for females (OR, 1.61; 95% CI, 1.02-2.54). In both communities, the prevalence of infection remained relatively constant after the age of 10. CONCLUSIONS: The prevalence of H. pylori in the two Indigenous communities was two to three times higher than that in the non-Indigenous Australian population and higher than that shown in previous studies in Indigenous Australians.     

Effect of dietary restriction on participation in faecal occult blood test screening for colorectal cancer

OBJECTIVES: To determine if participation in colorectal cancer screening using faecal occult blood testing (FOBT) is affected by a restrictive diet and if it is associated with certain demographic variables. PARTICIPANTS AND SETTING: 1,203 residents of South Australia aged 50-69 years, with no "currently active bowel disease", randomly selected from a database of people willing to be contacted about unspecified health issues. DESIGN: Randomised controlled trial: participants were offered screening by immunochemical FOBT by mail in 1998. Half were randomly allocated to a group instructed to follow a low-peroxidase diet, as required for guaiac FOBT, while the other group was not so restricted. MAIN OUTCOME MEASURES: Effect of diet restriction on participation (return of correctly completed FOBT sample cards within 15 weeks); time taken to return cards; relationships between participation and demographic variables. RESULTS: Participation rates were 65.9% (no-diet group) and 53.3% (diet group) (difference, 12.6%; 95% CI, 7.1%-18.1%). In the first week, rates of return as a proportion of all tests returned were 13.1% (no-diet) and 1.6% (diet) (difference, 11.5%; 95% CI, 8.6%-14.4%), increasing to 54.3% and 44.5%, respectively, after five weeks (difference, 9.8%; 95% CI, 4.2%-15.4%). Participation was significantly associated with older age (odds ratio, 1.40; 95% CI, 1.10-1.78), but not sex, Index of Social Disadvantage or rural versus urban address. CONCLUSIONS: Dietary restrictions create a barrier to FOBT-based screening for colorectal cancer. The use of immunochemical rather than guaiac FOBT removes this barrier.     

Rates of percutaneous coronary interventions and bypass surgery after acute myocardial infarction in Indigenous patients

OBJECTIVE: To compare rates of percutaneous coronary interventions (PCI) and bypass surgery after acute myocardial infarction (AMI) in Indigenous and non-Indigenous patients. DESIGN: Cohort study of public-sector patients who were followed up for 1 year using administrative hospital data. PARTICIPANTS AND SETTING: We followed up 14 683 public-sector patients admitted to Queensland hospitals for AMI between 1998 and 2002. Of these, 558 (3.8%) identified as Indigenous. OUTCOME MEASURES: Rates of PCI and bypass surgery, adjusted for differences between the Indigenous and non-Indigenous cohorts according to age, sex, socioeconomic status, remote residence, hospital characteristics, and comorbidities. RESULTS: The adjusted rate for PCI during the index admission was significantly lower by 39% (rate ratio [RR], 0.61; 95% CI, 0.38-0.98) among Indigenous versus non-Indigenous patients with AMI; the adjusted rate for subsequent PCI was significantly lower by 28% (RR, 0.72; 95% CI, 0.54-0.96). Adjusted rates for bypass surgery were similar in the two cohorts. For any coronary procedure (ie, PCI or bypass surgery), the adjusted rate was significantly lower by 22% (RR, 0.78; 95% CI, 0.64-0.94) among Indigenous patients with AMI. Diabetes, chronic renal failure, pneumonia, and chronic rheumatic fever were at least twice as common among Indigenous patients with AMI as in the rest of the cohort, and chronic bronchitis and emphysema and heart failure were at least 60% more common. If a patient had at least one comorbidity, then their probability of having a coronary procedure was reduced by 40%. CONCLUSIONS: There are likely to be several reasons for the lower rates of coronary procedures among Indigenous patients, but their high rates of comorbidities and the association of comorbidities with lower procedure rates was an important finding. As investment in primary care can reduce the prevalence and severity of comorbidities, we suggest that adequate primary health care is a prerequisite for effective specialist care.     

Survival of Indigenous and non-Indigenous Queenslanders after a diagnosis of lung cancer: a matched cohort study

OBJECTIVE: To compare survival of Indigenous and non-Indigenous lung cancer patients and to investigate any corresponding differences in stage, treatment and comorbidities. DESIGN AND SETTING: Cohort study of 158 Indigenous and 152 non-Indigenous patients (frequency-matched on age, sex and rurality) diagnosed with lung cancer between 1996 and 2002 and treated in Queensland public hospitals. MAIN OUTCOME MEASURES: Survival after diagnosis of lung cancer; effects of stage at diagnosis, treatment, comorbidities and histological subtype on lung cancer-specific survival. RESULTS: Survival of Indigenous lung cancer patients was significantly lower than that of non-Indigenous patients (median survival, 4.3 v 10.3 months; hazard ratio, 1.48; 95% CI, 1.14-1.92). Of 158 Indigenous patients, 72 (46%) received active treatment with chemotherapy, radiotherapy or surgery compared with 109 (72%) of the 152 non-Indigenous patients, and this treatment disparity remained after adjusting for histological subtype, stage at diagnosis, and comorbidities (adjusted risk ratio, 0.65; 95% CI, 0.53-0.73). The treatment disparity explained most of the survival deficit: the hazard ratio reduced to 1.10 (95% CI, 0.83-1.44) after inclusion of treatment variables in the proportional hazards survival model. The remaining survival deficit was explained by the higher prevalence of comorbidities among Indigenous cancer patients, mainly diabetes. CONCLUSION: Survival after a diagnosis of lung cancer is worse for Indigenous patients than for non-Indigenous patients, and differences in treatment between the two groups are mainly responsible.     

Delay times and management of acute myocardial infarction in indigenous and non-indigenous people in the Northern Territory

OBJECTIVES: To investigate differences in presentation and management of Indigenous and non-Indigenous patients hospitalised with acute myocardial infarction (AMI). DESIGN: Retrospective review of hospital medical records. PARTICIPANTS AND SETTING: 122 patients with definite or possible AMI admitted to hospitals in the Top End of the Northern Territory (NT) in 1996. MAIN OUTCOME MEASURES: Percentage receiving thrombolytic therapy; delays from symptom onset to primary and emergency department presentations, first and diagnostic electrocardiograms, thrombolytic therapy and aspirin; drugs prescribed during hospitalisation. RESULTS: Thrombolytic therapy was given to 12/41 Indigenous patients (29%) and 38/81 non-Indigenous patients (47%) (P = 0.06). Presentation delay over 12 hours was the reason for not giving thrombolytic therapy for 14/29 Indigenous patients (48%) and 8/43 non-Indigenous patients (19%) (P < 0.01). Median delay times were longer for Indigenous patients for all six categories of delay, although the difference was significant only for delay to emergency department presentation (10:00 versus 3:26 hours; P < 0.01) and to diagnostic electrocardiogram (8:10 versus 3:50 hours; P < 0.01). Delays were also longer for patients from rural compared with urban areas. Once diagnosed, Indigenous patients were as likely as non-Indigenous patients to receive aspirin (93% versus 96%) and beta-blockers (70% versus 69%) and more likely to receive angiotensin-converting enzyme inhibitors (60% versus 40%; P = 0.03). CONCLUSIONS: Delays in presentation affect Indigenous people living in rural and urban areas as well as non-Indigenous people living in rural areas. Concerted efforts are needed to improve health service access in rural areas and to encourage Indigenous people with persistent chest pain to present earlier.     

Cervical cancer screening in developing countries: why is it ineffective? The case of Mexico.

BACKGROUND: Mexico established a national cervical cancer-screening program in 1974. Despite the implementation of the program, there was a steady mortality trend of 16 per 100,000 women over 15 years. METHODS: A diagnostic procedure of the pitfalls was applied to the following steps of the screening procedure: Pap sampling quality; cytological diagnosis validity; compliance of women; and determinants of non-participation. RESULTS: The low effectiveness of screening on cervical cancer is principally due to factors associated with quality and coverage. Pap quality is deficient; 64% of a random sample of specimens lacked endocervical cells. Reading centers presented false negative indices of between 10 and 54%. Women seek screening in a late stage of disease (55% with cervical cancer seek care because they have symptoms). In addition, coverage is low; in women between 15 and 49 years of age in Mexico City, 64.2% have a history of Pap, compared with 30% in rural areas. Knowledge of what the Pap is used for strongly determines the use of screening. In rural areas, only 40% of women are informed about the purpose of the Pap test. CONCLUSIONS: A proposal to reorganize Mexico's screening program includes the following five main strategies: (a) increased coverage; (b) improved quality control of how cervical smears are taken; (c) better interpretation of Pap tests; (d) guaranteed treatment for those whose tests show abnormalities, and (e) improved follow-up.     

Characteristics of respondents to a cervical cancer screening program in a developing country

BACKGROUND: Characteristics associated with the response to a personalized, mailed invitation for the Papanicolaou (Pap) test vary among women. This study assesses the relationship between selected characteristics (e.g., demographic, obstetric, Pap history) and the response to a letter of invitation to undergo a Pap test among Mexican women affiliated with the Mexican Social Security Institute (IMSS). METHODS: Study subjects were 328 women affiliated with the IMSS who received and responded to a mailed letter of invitation, and 247 age- and clinically matched controls who received but did not respond to the letter of invitation. Statistical analysis consisted of multivariate conditional regression model. RESULTS: Having better housing conditions was one of the factors associated with letter response (medium level vs. low level, odds ratio [OR] = 3.17, 95% confidence interval [95% CI] = 2.46-4.09; high level vs. low level, OR = 2.65, 95% CI = 2.06-3.41). Other factors positively associated with letter response were greater number of pregnancies, previous Pap testing, being pleased at receipt of the letter of invitation, and knowing another woman who had received the invitation. Factors associated negatively to letter response were 7 or more years of formal education (> or =7 years vs. 0-6 years, OR = 0.50, 95% CI = 0.40-0.63), having a current job, availability of other medical services in addition to the IMSS, and willingness to receive Pap results by mail. CONCLUSIONS: Low educational level is not a limitation for cervical cancer screening call and recall among women affiliated with the IMSS.