Participation bias assessment in a community-based study of myocardial infarction, 2002-2005

Experiences and challenges faced by patients with COVID-19 who were hospitalised and participated in a randomised controlled trial: a qualitative study

OBJECTIVES

As part of a randomised controlled trial, this qualitative study aimed to identify experiences and challenges of hospitalised patients with COVID-19 during illness and treatment (objective 1: COVID-19-related perspectives; objective 2: trial participation-related perspectives).

DESIGN

Semistructured interviews following a prespecified interview guide, transcribed verbatim and analysed in accordance with the grounded theory process. Investigator triangulation served to ensure rigour of the analysis.

SETTING

Interviews were embedded in a multicentre, randomised, active-controlled, open-label platform trial testing efficacy and safety of experimental therapeutics for patients with COVID-19 (Austrian Corona Virus Adaptive Clinical Trial).

PARTICIPANTS

20 patients (60±15 years) providing 21 interviews from 8 June 2020 to 25 April 2021.

RESULTS

Qualitative data analysis revealed four central themes with subthemes. Theme 1, 'A Severe Disease', related to objective 1, was characterised by subthemes 'symptom burden', 'unpredictability of the disease course', 'fear of death' and 'long-term aftermaths with lifestyle consequences'. Theme 2, 'Saved and Burdened by Hospitalization', related to objective 1, comprised patients describing their in-hospital experience as 'safe haven' versus 'place of fear', highlighting the influence of 'isolation'. Theme 3, 'Managing One's Own Health', related to objective 1, showed how patients relied on 'self-management' and 'coping' strategies. Theme 4, 'Belief in Medical Research', related to objective 2, captured patients' 'motivation for study participation', many expressing 'information gaps' and 'situational helplessness' in response to study inclusion, while fewer mentioned 'therapy side-effects' and provided 'study reflection'. Investigator triangulation with an expert focus group of three doctors who worked at the study centre confirmed the plausibility of these results.

CONCLUSIONS

Several of the identified themes (2, 3, 4) are modifiable and open for interventions to improve care of patients with COVID-19. Patient-specific communication and information is of utmost importance during clinical trial participation, and was criticised by participants of the present study. Disease self-management should be actively encouraged.

TRIAL REGISTRATION NUMBER

NCT04351724.

Participation Bias in a Survey of Community Patients With Heart Failure

OBJECTIVE

To identify differences between participants and nonparticipants in a survey of physical and psychosocial aspects of health among a population-based sample of patients with heart failure (HF).

PATIENTS AND METHODS

Residents from 11 Minnesota counties with a first-ever code for HF (International Classification of Diseases, Ninth Revision 428 and Tenth Revision I50) between January 1, 2013, and December 31, 2016, were identified. Participants completed a questionnaire by mail or telephone. Characteristics and outcomes were extracted from medical records and compared between participants and nonparticipants. Response rate was calculated using guidelines of the American Association for Public Opinion Research. The association between nonparticipation and outcomes was examined using Cox proportional hazards regression for death and Andersen-Gill modeling for hospitalizations.

RESULTS

Among 7911 patients, 3438 responded to the survey (American Association for Public Opinion Research response rate calculated using formula 2 = 43%). Clinical and demographic differences between participants and nonparticipants were noted, particularly for education, marital status, and neuropsychiatric conditions. After a mean ± SD of 1.5±1.0 years after survey administration, 1575 deaths and 5857 hospitalizations occurred. Nonparticipation was associated with a 2-fold increased risk for death (hazard ratio, 2.29; 95% CI, 2.05-2.56) and 11% increased risk for hospitalization (hazard ratio, 1.11; 95% CI, 1.02-1.22) after adjusting for age, sex, time from HF diagnosis to index date, marital status, coronary disease, arrhythmia, hyperlipidemia, diabetes, cancer, chronic kidney disease, arthritis, osteoporosis, depression, and anxiety.

CONCLUSION

In a large survey of patients with HF, participation was associated with notable differences in clinical and demographic characteristics and outcomes. Examining the impact of participation is critical to draw inference from studies of patient-reported measures.

The interaction of personal, contextual, and study characteristics and their effect on recruitment and participation of pregnant women in research: a qualitative study in Lebanon

Background

Declining participation rates are impeding health research. Little is known about factors influencing the decision to participate in low- and middle-income countries (LMIC). Therefore, this paper reports on the various individual factors and their with contextual factors in influencing participation in research among pregnant women and the recommendations to enhance their recruitment in Lebanon.

Methods

This study used a qualitative research design drawing on focus groups and in-depth interviews. The Theoretical Domain Framework guided data collection and analysis. The three participant groups included: Group 1-Pregnant women (n = 25) attending public pre-natal events and antenatal clinics in Beirut; Group 2-Pregnant women (n = 6) already enrolled in the ongoing Mother and Infant Nutritional Assessment birth cohort study; Group 3-Key informants (n = 13) including health care workers involved in recruiting pregnant women. Conversations were audio recorded, transcribed, translated into English, and thematically analyzed.

Results

Three main factors influencing participation were revealed, with each factor encompassing several sub-themes: (1) personal factors (altruism, self-confidence, personal interest in the topic, previous understanding of the nature and purpose of research, education level, and previous research experience), (2) contextual factors (societal factors, family and friends), and (3) study characteristics (burden of the study, ethical considerations, incentives, and research interpersonal skills and physician endorsement to participate). The results suggested a dynamic interaction among the identified factors, forming two intersecting axes, with a four-quadrant configuration. The y- and x-axes represented personal factors and contextual factors, respectively. Individuals positioned on the lower-left quadrant were the least likely to participate; those on the upper-right quadrant were the most likely to participate; while those on the upper-left and lower-right quadrants were indecisive. Study characteristics seemed to affect the decision of pregnant women to participate situated in any of the four quadrants. Specific recommendations to improve participation were also identified.

Conclusions

Our findings suggested an interaction of personal factors, contextual factors, and study characteristics affecting subjects’ participation. This interaction integrates factors into a novel dynamic framework that could be used in future studies. The recommendations identified may help improve participation of pregnant women in health research hence enhancing the quality and generalizability of research findings in LMIC.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0616-5) contains supplementary material, which is available to authorized users.

Are patients with longer emergency department wait times less likely to consent to research?

OBJECTIVES

There are unique challenges to enrolling patients in emergency department (ED) clinical research studies, including the time-sensitive nature of emergency conditions, the acute care environment, and the lack of an established relationship with patients. Prolonged ED wait times have been associated with a variety of adverse effects on patient care. The objective of this study was to assess the effect of ED wait times on patient participation in ED clinical research. The hypothesis was that increased ED wait times would be associated with reduced ED clinical research consent rates.

METHODS

This was a retrospective cohort study of all patients eligible for two diagnostic clinical research studies from January 1, 2008, through December 31, 2008, in an urban academic ED. Sex, age, race, study eligibility, and research consent decisions were recorded by trained study personnel. The wait times to registration and to be seen by a physician were obtained from administrative databases and compared between consenters and nonconsenters. An analysis of association between patient wait times for the outcome of consent to participate was performed using a multivariate logistic regression model.

RESULTS

A total of 903 patients were eligible for enrollment and were asked for consent. Overall, 589 eligible patients (65%) gave consent to research participation. The consent rates did not change when patients were stratified by the highest and lowest quartile wait times for both time from arrival to registration (68% vs. 65%, p = 0.35) and time to be seen by a physician (65% vs. 66%, p = 0.58). After adjusting for patient demographics (age, race, and sex) and study, there was still no relationship between wait times and consent (p > 0.4 for both wait times). Furthermore, median time from arrival to registration did not differ between those who consented to participate (15 minutes; interquartile range [IQR] = 9 to 36 minutes) versus those who did not (15.5 minutes; IQR = 10 to 39 minutes; p = 0.80; odds ratio [OR] = 1.00, 95% confidence interval [CI] = 0.99 to 1.01). Similarly, there was no difference in the median time to be seen by a physician between those who consented (25 minutes; IQR = 15 to 55 minutes) versus those who did not (25 minutes; IQR = 15 to 56 minutes; p = 0.70; OR = 1.00, 95% CI = 0.99 to 1.01).

CONCLUSIONS

Regardless of wait times, nearly two-thirds of eligible patients were willing to consent to diagnostic research studies in the ED. These findings suggest that effective enrollment in clinical research is possible in the ED, despite challenges with prolonged wait times.

Consenting to health record linkage: evidence from a multi-purpose longitudinal survey of a general population

Background

The British Household Panel Survey (BHPS) is the first long-running UK longitudinal survey with a non-medical focus and a sample covering the whole age range to have asked for permission to link to a range of administrative health records. This study determines whether informed consent led to selection bias and reflects on the value of the BHPS linked with health records for epidemiological research.

Methods

Multivariate logistical regression is used, with whether the respondent gave consent to data linkage or not as the dependent variable. Independent variables were entered as four blocks; (i) a set of standard demographics likely to be found in most health registration data, (ii) a broader set of socio-economic characteristics, (iii) a set of indicators of health conditions and (iv) information about the use of health services.

Results

Participants aged 16-24, males and those living in England were more likely to consent. Consent is not biased with respect to socio-economic characteristics or health. Recent users of GP services are underrepresented among consenters.

Conclusions

Whilst data could only be linked for a minority of BHPS participants, the BHPS offers a great range of information on people's life histories, their attitudes and behaviours making it an invaluable source for epidemiological research.

Prognostic value of cardiac troponin T after myocardial infarction: a contemporary community experience

OBJECTIVE

To evaluate the role of cardiac troponin T (cTnT) in predicting death, recurrent ischemic events, and heart failure among community-dwelling persons with first myocardial infarction (MI).

PATIENTS AND METHODS

Consecutive Olmsted County, Minnesota, residents with an incident MI between November 6, 2002, and December 31, 2007, were studied (N=1177; mean age, 68 years). Maximal cTnT value was measured at a median of 1 day after MI (median, 0.52 ng/mL; interquartile range, 0.16-1.75 ng/mL) and evaluated as a prognostic factor using measures of absolute risk.

RESULTS

During a mean follow-up of 16 months, 276 deaths (23%) occurred, 341 patients (29%) experienced a recurrent ischemic event, and 326 patients (28%) experienced heart failure. A dose-response relationship was demonstrated early after MI between cTnT and the adjusted cumulative incidence of all outcomes. The multivariate-adjusted absolute risk differences (events per 100 patients) between the upper and lower cTnT tertiles at 30 days were 5.8 (95% confidence interval [CI], 1.4-10.2) for death, 5.2 (95% CI, 0.2-10.3) for recurrent ischemic event, and 6.9 (95% CI, 1.4-12.4) for heart failure. These differences were either maintained or increased at 2 years.

CONCLUSION

In the community, cTnT level predicts death and nonfatal cardiac events independently of other prognostic factors. The increased risk associated with elevated cTnT level appears shortly after MI and persists for at least 2 years.

Comparison of participants and non-participants to the ORISCAV-LUX population-based study on cardiovascular risk factors in Luxembourg

Background

Poor response is a major concern in public health surveys. In a population-based ORISCAV-LUX study carried out in Grand-Duchy of Luxembourg to assess the cardiovascular risk factors, the non-response rate was not negligible. The aims of the present work were: 1) to investigate the representativeness of study sample to the general population, and 2) to compare the known demographic and cardiovascular health-related profiles of participants and non-participants.

Methods

For sample representativeness, the participants were compared to the source population according to stratification criteria (age, sex and district of residence). Based on complementary information from the "medical administrative database", further analysis was carried out to assess whether the health status affected the response rate. Several demographic and morbidity indicators were used in the univariate comparison between participants and non-participants.

Results

Among the 4452 potentially eligible subjects contacted for the study, there were finally 1432 (32.2%) participants. Compared to the source population, no differences were found for gender and district distribution. By contrast, the youngest age group was under-represented while adults and elderly were over-represented in the sample, for both genders. Globally, the investigated clinical profile of the non-participants was similar to that of participants. Hospital admission and cardiovascular health-related medical measures were comparable in both groups even after controlling for age. The participation rate was lower in Portuguese residents as compared to Luxembourgish (OR = 0.58, 95% CI: 0.48-0.69). It was also significantly associated with the professional status (P < 0.0001). Subjects from the working class were less receptive to the study than those from other professional categories.

Conclusion

The 32.2% participation rate obtained in the ORISCAV-LUX survey represents the realistic achievable rate for this type of multiple-stage, nationwide, population-based surveys. It corresponds to the expected rate upon which the sample size was calculated. Given the absence of discriminating health profiles between participants and non-participants, it can be concluded that the response rate does not invalidate the results and allows generalizing the findings for the population.

Item nonresponse to psychosocial questionnaires was associated with higher mortality after acute myocardial infarction

OBJECTIVE

To examine the relationship between selective nonresponse to a psychosocial questionnaire and mortality after acute myocardial infarction (AMI).

STUDY DESIGN AND SETTING

Two thousand six hundred and ninety AMI survivors after AMI hospitalization were recruited to complete a 30-day follow-up interview. Patients were classified into four groups (survey nonparticipation and complete, partial, and no item nonresponse) according to their degree of response to the Medical Outcomes Study (MOS) Social Support Survey (MOS-SSS). Cox proportional hazard models, adjusted for baseline sociodemographic, clinical, and psychosocial (i.e., social isolation) characteristics, were used to examine all-cause mortality, 3 years post-AMI, across the response levels.

RESULTS

13.9% of the eligible patients refused follow-up participation; MOS-SSS item nonresponse was present in up to 14.7% of participants and was more frequent among the elderly, socially disadvantaged, and those with higher clinical risk. A nonresponse mortality gradient existed, ranging from 8.9% (no item nonresponse) to 18.7% (complete item nonresponse) (P<0.001). After adjusting for baseline characteristics, complete item nonresponse remained significantly associated with mortality (hazard ratio: 1.33; 95% confidence interval: 1.02-1.73).

CONCLUSIONS

Item nonresponse to a social support questionnaire is associated with higher mortality post-AMI. Although explanatory factors may include age and baseline clinical risk, additional psychosocial and/or unmeasured factors may account for the poorer prognosis.

Pretreatment health behaviors predict survival among patients with head and neck squamous cell carcinoma

PURPOSE

Our prior work has shown that the health behaviors of head and neck cancer patients are interrelated and are associated with quality of life; however, other than smoking, the relationship between health behaviors and survival is unclear.

PATIENTS AND METHODS

A prospective cohort study was conducted to determine the relationship between five pretreatment health behaviors (smoking, alcohol, diet, physical activity, and sleep) and all-cause survival among 504 head and neck cancer patients.

RESULTS

Smoking status was the strongest predictor of survival, with both current smokers (hazard ratio [HR] = 2.4; 95% CI, 1.3 to 4.4) and former smokers (HR = 2.0; 95% CI, 1.2 to 3.5) showing significant associations with poor survival. Problem drinking was associated with survival in the univariate analysis (HR = 1.4; 95% CI, 1.0 to 2.0) but lost significance when controlling for other factors. Low fruit intake was negatively associated with survival in the univariate analysis only (HR = 1.6; 95% CI, 1.1 to 2.1), whereas vegetable intake was not significant in either univariate or multivariate analyses. Although physical activity was associated with survival in the univariate analysis (HR = 0.95; 95% CI, 0.93 to 0.97), it was not significant in the multivariate model. Sleep was not significantly associated with survival in either univariate or multivariate analysis. Control variables that were also independently associated with survival in the multivariate analysis were age, education, tumor site, cancer stage, and surgical treatment.

CONCLUSION

Variation in selected pretreatment health behaviors (eg, smoking, fruit intake, and physical activity) in this population is associated with variation in survival.

Healthy women's motivators and barriers to participation in a breast cancer cohort study: a qualitative study

PURPOSE

This focus group study describes motivators and barriers to participation in the Mayo Mammography Health Study (MMHS), a large-scale longitudinal study examining the causal association of breast density with breast cancer, involving completion of a survey, providing access to a residual blood sample for genetic analyses, and sharing their results from a screening mammogram. These women would then be followed up long term for breast cancer incidence and mortality.

METHODS

Forty-eight women participated in six focus groups, four with MMHS non-respondents (n = 27), and two with MMHS respondents (n = 21). Major themes were summarized using content analysis. Social cognitive theory (SCT) was used as a framework for interpretation of the findings.

RESULTS

Barriers to participation among MMHS non-respondents were 1) lack of confidence in their ability to fill out the survey accurately (self-efficacy); 2) lack of perceived personal connection to the study or value of participation (expectancies); and 3) fear related to some questions about perceived cancer risk and worry/concern (emotional coping responses). Among MMHS respondents, personal experience with cancer was reported as a primary motivator for participation (expectancies).

CONCLUSIONS

Application of a theoretical model such as social cognitive therapy to the development of a study recruitment plan could be used to improve rates of study participation and provide a reproducible and evaluable strategy.

Plasma lipoprotein-associated phospholipase A2 levels in heart failure: association with mortality in the community

OBJECTIVE

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a useful inflammatory marker of cardiovascular risk, yet little is known of its prognostic role in heart failure (HF). We evaluated the association of Lp-PLA2 with mortality in subjects with HF and assessed its incremental value for risk discrimination over established risk factors and biomarkers.

METHODS

Residents of Olmsted County, MN, diagnosed with HF between September 2003 and April 2007 (n=646, mean age 76 years, 51% women) were prospectively enrolled and followed-up. Plasma Lp-PLA2 levels were measured at baseline and evaluated along with known risk indicators.

RESULTS

Lp-PLA2 was positively associated with male gender and low-density lipoprotein cholesterol and inversely associated with statin use and diabetes. During follow-up (median 21 months), 213 deaths occurred. Elevated Lp-PLA2 was associated with an increased risk of mortality (hazard ratio (HR)=1.57; 95% confidence interval (CI): 1.03-2.37; P=0.035, per 1-unit increase in the log-transformed values). The relationship differed markedly by age (P(interaction)=0.003), with a strong association in patients under 80 years (covariate-adjusted HR=3.83; 95% CI: 1.93-7.61; P<0.001) and none in older ones (covariate-adjusted HR=0.82; 95% CI: 0.44-1.51; P=0.55). For the younger subjects, an improvement in the model's discriminatory power was obtained by adding Lp-PLA2 to established risk indicators and biomarkers (area under the receiver operating characteristic curve, 0.709-0.744, P(difference)=0.008).

CONCLUSION

In this community-based cohort of patients with HF, Lp-PLA2 was strongly and independently associated with mortality and contributed incrementally to risk discrimination in patients under 80 years of age.

Day-night variation of acute myocardial infarction in obstructive sleep apnea

OBJECTIVES

This study sought to evaluate the day-night variation of acute myocardial infarction (MI) in patients with obstructive sleep apnea (OSA).

BACKGROUND

Obstructive sleep apnea has a high prevalence and is characterized by acute nocturnal hemodynamic and neurohormonal abnormalities that may increase the risk of MI during the night.

METHODS

We prospectively studied 92 patients with MI for which the time of onset of chest pain was clearly identified. The presence of OSA was determined by overnight polysomnography.

RESULTS

For patients with and without OSA, we compared the frequency of MI during different intervals of the day based on the onset time of chest pain. The groups had similar prevalence of comorbidities. Myocardial infarction occurred between 12 am and 6 am in 32% of OSA patients and 7% of non-OSA patients (p = 0.01). The odds of having OSA in those patients whose MI occurred between 12 am and 6 am was 6-fold higher than in the remaining 18 h of the day (95% confidence interval: 1.3 to 27.3, p = 0.01). Of all patients having an MI between 12 am and 6 am, 91% had OSA.

CONCLUSIONS

The diurnal variation in the onset of MI in OSA patients is strikingly different from the diurnal variation in non-OSA patients. Patients with nocturnal onset of MI have a high likelihood of having OSA. These findings suggest that OSA may be a trigger for MI. Patients having nocturnal onset of MI should be evaluated for OSA, and future research should address the effects of OSA therapy for prevention of nocturnal cardiac events.

Neighborhood income and individual education: effect on survival after myocardial infarction

OBJECTIVE

To evaluate the association of neighborhood-level income and individual-level education with post-myocardial infarction (MI) mortality in community patients.

PARTICIPANTS AND METHODS

From November 1, 2002, through May 31, 2006, 705 (mean+/-SD age, 69+/-15 years; 44% women) residents of Olmsted County, MN, who experienced an MI meeting standardized criteria were prospectively enrolled and followed up. The neighborhood's median household income was estimated by census tract data; education was self-reported. Demographic and clinical variables were obtained from the medical records.

RESULTS

Living in a less affluent neighborhood and having a low educational level were both associated with older age and more comorbidity. During follow-up (median, 13 months), 155 patients died. Neighborhood income (hazard ratio [HR], 2.10; 95% confidence interval [CI], 1.42-3.12; for lowest [median, $34,205] vs highest [median, $60,652] tertile) and individual education (HR, 2.21; 95% CI, 1.47-3.32; for <12 vs >12 years) were independently associated with mortality risk. Adjustment for demographics and various post-MI prognostic indicators attenuated these estimates, yet excess risk persisted for low neighborhood income (HR, 1.62; 95% CI, 1.08-2.45). Modeled as a continuous variable, each $10,000 increase in annual income was associated with a 10% reduction in mortality risk (adjusted HR, 0.90; 95% CI, 0.82-0.99).

CONCLUSION

In this geographically defined cohort of patients with MI, low individual education and poor neighborhood income were associated with a worse clinical presentation. Poor neighborhood income was a powerful predictor of mortality even after controlling for a variety of potential confounding factors. These data confirm the socioeconomic disparities in health after MI.

Participation bias and its impact on the assembly of a genetic specimen repository for a myocardial infarction cohort

OBJECTIVE

To assess participation bias in the assembly of a specimen repository for genetic studies and to examine the association of participation with outcome within the Olmsted County myocardial infarction (MI) cohort.

PARTICIPANTS AND METHODS

From January 1, 1979, to May 31, 2006, 3081 persons had MI in Olmsted County, MN. Face-to-face contact was used to recruit patients who were hospitalized for an acute event. Persons who had had an MI before establishment of this repository were contacted by mail. At initial contact, we sought consent to use blood samples for genetic studies. Persons who refused were contacted by mail and were asked to consent to the use of stored tissue samples. For deceased subjects, stored tissue was collected when available.

RESULTS

Of the 3081 persons in the Olmsted County MI cohort, 1994 participated in the study; 1007 (50.5%) blood and 987 (49.5%) tissue specimens were provided. Participants were more likely to be younger men with hypertension, comorbidities, and non-ST-segment elevation MI (all, P<.05). Participants who provided blood specimens were more likely to have non-ST-segment elevation MI and lower Killip class than those who provided tissue. After adjustment for age, sex, hypertension, ST-segment elevation, Killip class, and comorbidities, participation was not associated with outcome. Participants who provided blood specimens were less likely to have heart failure (hazard ratio, 0.49; 95% confidence interval, 0.40-0.59; P<.01) or to die (hazard ratio, 0.16; 95% confidence interval, 0.12-0.21; P<.01) than those who provided tissue.

CONCLUSION

A variety of sources can be used to assemble community specimen repositories. Baseline characteristics differed between participants and nonparticipants and, among participants, by specimen source. Participants who provided blood specimens had better outcomes than those who provided tissue specimens. No survival advantage was observed for participants after combining blood and tissue specimens.