Outpatient Follow-Up Visit after Hospital Discharge Lowers Risk of Rehospitalization in Patients with Schizophrenia: A Nationwide Population-Based Study

Identification of factors associated with hospitalization in an outpatient population with mental health conditions: a case-control study

Introduction

Addressing relevant determinants for preserved person-centered rehabilitation in mental health is still a major challenge. Little research focuses on factors associated with psychiatric hospitalization in exclusive outpatient settings. Some variables have been identified, but evidence across studies is inconsistent. This study aimed to identify and confirm factors associated with hospitalization in a specific outpatient population.

Methods

A retrospective monocentric case-control study with 617 adult outpatients (216 cases and 401 controls) from a French community-based care facility was conducted. Participants had an index outpatient consultation between June 2021 and February 2023. All cases, who were patients with a psychiatric hospitalization from the day after the index outpatient consultation and up to 1 year later, have been included. Controls have been randomly selected from the same facility and did not experience a psychiatric hospitalization in the 12 months following the index outpatient consultation. Data collection was performed from electronic medical records. Sociodemographic, psychiatric diagnosis, historical issues, lifestyle, and follow-up-related variables were collected retrospectively. Uni- and bivariate analyses were performed, followed by a multivariable logistic regression.

Results

Visit to a psychiatric emergency within a year (adjusted odds ratio (aOR): 13.02, 95% confidence interval (CI): 7.32-23.97), drug treatment discontinuation within a year (aOR: 6.43, 95% CI: 3.52-12.03), history of mental healthcare without consent (aOR: 5.48, 95% CI: 3.10-10.06), medical follow-up discontinuation within a year (aOR: 3.17, 95% CI: 1.70-5.95), history of attempted suicide (aOR: 2.50, 95% CI: 1.48-4.30) and unskilled job (aOR: 0.26, 95% CI: 0.10-0.65) are the independent variables found associated with hospitalization for followed up outpatients.

Conclusions

Public health policies and tools at the local and national levels should be adapted to target the identified individual determinants in order to prevent outpatients from being hospitalized.

Are early post-discharge physician contacts associated with 30-day psychiatric re-hospitalisation? A nationwide claims data based retrospective cohort study in Austria free of immortal time bias

OBJECTIVES

Cost containment and quality of care considerations have increased research interest in the potential preventability of early re-hospitalisations. Various registry-based retrospective cohort studies on psychiatric re-hospitalisation have focused on the role of early post-discharge service contacts, but either did not consider their time-dependent nature ('immortal time bias') or evaded the issue by analysing late re-hospitalisations. The present study takes care of the immortal time bias in studying early psychiatric re-hospitalisations.

METHODS

In a retrospective cohort study using nationwide electronic claims data in Austria, 10,689 adults discharged from acute psychiatric inpatient wards were followed up for 30 days. Cox regression analyses were performed with post-discharge psychiatric and general practitioner contacts as time-dependent covariates and time to first psychiatric re-hospitalisation as outcome.

RESULTS

Post-discharge ambulatory physician contacts were significantly associated with a decreased psychiatric re-hospitalisation rate (hazard ratio 0.77 [95% CI 0.69; 0.87], p < 0.0001), with similarly strong contributions to this association by general practitioners and psychiatrists.

CONCLUSIONS

Despite avoiding the immortal time bias and controlling for several confounders, we suggest to be cautious with a causal interpretation of the identified association, since potentially relevant confounders, such as disease severity, were unavailable in our claims data base.

Continuity of care among patients newly initiated on second-generation oral or long-acting injectable antipsychotics during a schizophrenia-related inpatient stay

BACKGROUND

Maintaining continuity of care after schizophrenia-related hospitalization is challenging for patients and healthcare providers and systems. Prior evidence suggests that second-generation long-acting injectable antipsychotics (SGLAIs) may reduce the risk of treatment nonadherence and readmission versus oral atypical antipsychotics (OAAs). Therefore, quality measures were compared between patients initiated on SGLAIs and OAAs in the United States.

METHODS

Adults newly initiated on an SGLAI or OAA during a schizophrenia-related inpatient stay were identified in HealthVerity databases (01/2015-12/2020); the index date was the hospital discharge date. Patients had continuous health insurance coverage for pharmacy and medical services for 6 months pre-admission and post-discharge from the inpatient stay and ≥1 pharmacy or medical claim (i.e. treatment as indicated by the observed insurance claims) for an antipsychotic other than the index SGLAI or OAA in the 6 months pre-admission. Antipsychotic use and adherence, and schizophrenia-related readmissions and outpatient visits were compared during the 6-month period post-discharge. Characteristics between cohorts were balanced using inverse probability weights.

RESULTS

Post-discharge, only 36.9% and 40.7% of weighted SGLAI (N = 466) and OAA (N = 517) patients had ≥1 pharmacy or medical claim for the antipsychotic initiated during the inpatient stay, among whom SGLAI patients were 4.4 times more likely to be adherent to that antipsychotic compared to OAA patients (p < .001). Additionally, SGLAI patients were 2.3 and 3.0 times more likely to have a pharmacy or medical claim for and be adherent to any antipsychotic relative to OAA patients (including index antipsychotic; all p < .001). Within 7 and 30 days post-discharge, 1.7% and 13.0% of SGLAI patients and 4.1% and 12.6% of OAA patients had a readmission. Further, SGLAI patients were 51% more likely to have an outpatient visit compared to OAA patients (p = .044).

CONCLUSIONS

Less than half of patients initiated on antipsychotics during a schizophrenia-related inpatient stay continued the same treatment post-discharge. However, SGLAI patients were more likely to be adherent to the initiated antipsychotic and to have an outpatient visit, which may suggest improved continuity of care post-discharge relative to OAA patients.

Risk factors for readmission in schizophrenia treated with combined psychoeducation and standard therapy

Background

We conducted a historical cohort study of patients with schizophrenia to identify more robust risk factors at discharge that contribute to readmission within a year.

Methods and Findings

The subjects underwent brief psychoeducation during hospitalization. Multivariate analysis was conducted using factors selected in the univariate analysis. Using logistic regression analysis, the number of hospital admissions (P = .01) and Schedule for Assessment of Insight Japanese version score (P = .04) were identified as risk factors for readmission, with odds ratios of 0.70 and 1.18, respectively.

Conclusions

These results suggest that improvement in insight and early intervention may lead to a more stable community life.

We conducted a historical cohort study of patients with schizophrenia to identify more robust risk factors at discharge that contribute to readmission within a year. The number of hospital admissions and Schedule for Assessment of Insight Japanese version score were identified as risk factors for readmission.

Addressing the Needs of People with Schizophrenia in South Africa During the COVID-19 Pandemic

Research indicates that most people with Schizophrenia from low to middle-income countries do not receive adequate healthcare. Inadequate policies, lack of funding, poor service planning and neglect are some barriers to adequate care. Intrinsic barriers to care include stigma, lack of insight, and pathways to care that are often driven by cultural beliefs, and many systemic challenges. South Africa was not spared from the scourge of COVID-19, hosting a third of all reported cases in Africa. In a country with disparities, it would be of interest to get insight into the situation concerning the healthcare needs of people with Schizophrenia during the pandemic. A pandemic such as COVID-19 placed enormous strains on already limited and unequally distributed health care resources. In this paper, we discuss: (1) The South African healthcare system (with respect to Schizophrenia care). (2) COVID-19 policies related to the care of people with Schizophrenia (testing, access to vaccine). (3) Managing people with Schizophrenia amid the COVID-19 pandemic. (4) Recommendations.

Nonadherence after hospital discharge in patients with schizophrenia or schizoaffective disorder: A six-month naturalistic follow-up study

BACKGROUND

Despite a wealth of studies seeking to identify factors associated with nonadherence few consistent predictors have been determined, and several gaps still exist in the literature.

METHOD

We assessed 110 consecutively admitted patients diagnosed with schizophrenia or schizoaffective disorder according to ICD-10 criteria. Assessments were performed during hospitalization and at six-months follow-up. Evaluation included sociodemographic, clinical, psychopathologic and treatment-related variables. Prevalence of nonadherence, associated variables, reasons for nonadherence and possible subtypes were explored. Adherence was defined as the concurrence of adherence to antipsychotic treatment and adherence to outpatient follow-up, during the six-month period.

RESULTS

Nonadherence was detected in 58.2% of patients. An identifiable profile was found in nonadherent patients. After multivariate logistic regression analysis, low socio-economic level (OR = 3.68; 95% CI = 1.42-9.53), current cannabis use or abuse (OR = 2.79; 95% CI = 1.07-7.28), nonadherence as a reason for relapse and admission (OR = 5.46; 95% CI = 2.00-14.90), and greater overall severity of symptoms at six months follow-up (OR = 2.00; 95% CI = 1.02-3.95) remained independently associated with nonadherence. Believing that medication is unnecessary was the most reported reason for nonadherence. For nonadherent patients (N = 64), two distinguishable subtypes were found: intentional nonadherence (N = 32; 50%), and unintentional nonadherence (N = 32; 50%).

CONCLUSIONS

A large percentage of patients with schizophrenia or schizoaffective disorder did not adhere to their treatment in the post-discharge follow-up period. The profile identified may enable better prevention of this problem. Specific reasons for nonadherence should also be explored to provide individualized strategies.

Improving community care for patients discharged from hospital through zone-wide implementation of a seamless care transition policy

BACKGROUND

Several studies within the psychiatry literature have illustrated the importance of discharge planning and execution, as well as accessibility of outpatient follow-up post-discharge. We report the results of implementing a new seamless care transition policy to expedite post-discharge follow-up in the community Addiction and Mental Health (AMH) program in the Edmonton Zone, Alberta, Canada. The policy involved a distribution mechanism for assessment by a mental health therapist (MHT) within 7 days of discharge as well as a dedicated roster of community psychiatrists to accept newly discharged patients.

OBJECTIVE

Our aim was to assess the feasibility of this novel policy and to assess its effect on our outcome measures of wait time to first outpatient MHT assessment and re-admission rate to hospital.

METHODS

Our study involved a retrospective clinical audit with total sampling design and a comparison of data 1 year before (2015/2016 fiscal year) and 1 year after (2017/2018 fiscal year) the implementation of the seamless care policy within the Edmonton Zone. Extracted data were analyzed with simple descriptive statistics and presented as percentages, mean and median.

RESULTS

Overall, with the enactment of this policy, follow-up volumes ultimately increased, while wait times for initial assessment decreased on average for patients discharged from the hospital. In the 2015/2016 fiscal year, MHT completed 128 assessments of post-discharge patients who were new to the community AMH program compared to 298 completed new assessments for the 2017/2018 fiscal year. The corresponding wait times for the new MHT assessments were 12.7 days (median of 12 days) and 7.8 days (median of 6 days), respectively. Similarly, psychiatrists completed only 59 assessments of post-discharge patients who were new to AMH compared to 133 new psychiatric assessments for the 2017/2018 fiscal year. The corresponding wait times for the new psychiatric assessments were 15.3 days (median of 14 days) and 8.8 days (median of 7 days), respectively. We correspondingly found a slight decline in readmission rates after the implementation of our model in the subsequent fiscal year.

CONCLUSION

We envision that this policy will set a precedent with regard to streamlining post-discharge follow-up care for admitted inpatients, ultimately improving mental health outcomes for patients.

Downstream hospital system effects of a comprehensive trauma recovery services program

BACKGROUND

Trauma patients are often noted to have poor compliance but high recidivism and readmission rates. Participation in a trauma recovery services (TRS) program, which provides peer support and other psychosocial resources, may impact the trajectory of patient recovery by decreasing barriers to follow-up. We hypothesized that TRS participants would have greater downstream nonemergent use of our hospital system over the year following trauma, manifested by more positive encounters, fewer negative encounters, and lower emergency department (ED) charges.

METHODS

We studied trauma survivors (March 2017 to March 2018) offered TRS. Hospital encounters and charges 1 year from index admission were compared between patients who accepted and declined TRS. Positive encounters were defined as outpatient visits and planned admissions; negative encounters were defined as no shows, ED visits, and unplanned admissions. Charges were grouped as cumulative ED and non-ED charges (including outpatient and subsequent admission charges). Adjusted logistic and linear regression analyses were used to identify factors associated with positive/negative encounters and ED charges.

RESULTS

Of 511 identified patients (68% male; injury severity score, 14 [9-19]), 362 (71%) accepted TRS. Trauma recovery services patients were older, had higher injury severity, and longer index admission length of stay (all p < 0.05). After adjusting for confounders, TRS patients were more likely to have at least one positive encounter and were similarly likely to have negative encounters as patients who declined services. Total aggregate charges for this group was US $74 million, of which US $30 million occurred downstream of the index admission. Accepting TRS was associated with lower ED charges.

CONCLUSION

A comprehensive TRS program including education, peer mentors, and a support network may provide value to the patient and the health care system by reducing subsequent care provided by the ED in the year after a trauma without affecting nonemergent care.

LEVEL OF EVIDENCE

Therapeutic/care management, level IV.

The effect of non-adherence to antipsychotic treatment on rehospitalization in patients with psychotic disorders

BACKGROUND AND AIMS

Many patients with psychotic disorders are non-adherent to antipsychotic (AP) medication(s), potentially contributing to rehospitalization. It is unknown whether non-adherence in different phases of AP use is associated with rehospitalization. The aim of this study was to assess the association between non-adherence to APs and rehospitalization in patients with psychotic disorders. Non-adherence was assessed specifically for the initiation, continued drug use and early discontinuation of AP use.

METHODS

A retrospective follow-up study was performed. Adult patients were included at discharge if they suffered from schizophrenia, psychotic, or bipolar I disorder; had been hospitalized in a psychiatric hospital for ⩾7 days; and were treated with oral APs. Patients discharged between January 2006 and December 2009 from Altrecht Mental Health Care were included. Non-adherence was studied in the three phases of medication use: initiation, continued drug use (implementation) and (early) discontinuation after discharge until the end of follow up or until patients were rehospitalized. Cox regression analysis was used to assess the strength of the association between non-adherence for the different phases of AP use and rehospitalization during follow up and expressed as relative risk (RR) with 95% confidence intervals (CI).

RESULTS

A total of 417 patients were included. Patients who did not initiate their APs compared with those who did in the first month (RR = 1.62, 95% CI: 1.19-2.19) and between the first and third month after discharge (RR = 1.70, 95% CI: 1.04-2.79) had the highest risk for rehospitalization during follow up. Overall, patients who did not initiate their AP medication within the first year after discharge had a RR of 2.70 (95% CI: 1.97-3.68) for rehospitalization during follow up compared with those that initiated their AP.

CONCLUSION

Not initiating APs right after discharge was associated with an increased risk of rehospitalization. Interventions should aim to promote the initiation of APs soon after discharge to minimize the risk of rehospitalization.

Improving the "real life" management of schizophrenia spectrum disorders by LAI antipsychotics: A one-year mirror-image retrospective study in community mental health services

Schizophrenia poses a significant economic burden on the healthcare system as well as it has a significant impact on society at large. Reasons for such a high economic burden of schizophrenia include the frequent relapses and hospitalizations occurring in this disorder. We analyze the effectiveness of long-acting injectable antipsychotics (LAIs) compared to oral medications, in terms of “clinical process management” in a sample of patients with a diagnosis of schizophrenia spectrum disorder treated in community mental health centers. An observational, retrospective, mirror-image study was carried out to evaluate the effectiveness of LAIs compared to oral medications in terms of number of hospitalizations, emergency visits and planned visits on a 10-year period (from July 2007 to June 2017). Differences between first and second generation LAIs were also explored. Our findings show that hospitalization and emergency visits are significantly decreased with the use of LAIs, while planned visits are increased in patients treated with LAIs. Our results suggest that LAIs, in particular, second generation ones, reduce hospitalization rates and emergency visits, improving the economic burden of schizophrenia. Therefore, LAIs should be considered a cost-effective treatment in the management of schizophrenia under routine conditions.

Psychiatric-related Revisits to the Emergency Department Following Rapid Expansion of Community Mental Health Services

OBJECTIVES

Repeat visits (revisits) to emergency departments (EDs) for psychiatric care reflect poor continuity of care and impose a high financial cost. We test whether rapid expansion of community health centers (CHCs)-which provide regional, low-cost primary care-correspond with fewer repeat psychiatric-related ED visits (PREDVs).

METHODS

We obtained repeated cross-sectional time-series data for 7.8 million PREDVs from the State Emergency Department Database for four populous U.S. states (California, Florida, North Carolina, and New York) from 2006 to 2011. We specified as the outcome variable the count of repeat visits per ED visitor with a psychiatric diagnosis. We retrieved aggregate-level mental health visits at CHCs from the Uniform Data System. Negative binomial regression methods controlled for individual-level confounders, county health system and sociodemographic attributes, year fixed effects, and county fixed effects.

RESULTS

The risk of a repeat PREDV decreased with a county-level increase in mental health patients seen at CHCs (incidence rate ratio = 0.986, 95% confidence interval = 0.98 to 0.99). Conversion of this rate ratio to the number of revisits averted indicated 34,000 fewer repeat PREDVs in these four states statistically associated with a 1% expansion in CHC mental health visits. Exploratory analyses found that revisits decline for relatively mild/moderate illnesses (e.g., mood, anxiety disorders) but not for severe illnesses (e.g., schizophrenia/psychoses).

CONCLUSION

An increase in mental health services at CHCs corresponds with a modest decline in repeat PREDVs. This decline concentrates among those with less severe mental illnesses.

Healthcare cost, service use and mortality in major psychiatric disorders in Taiwan

BACKGROUND

We aimed to examine the differences in the cost distributions, service use, and mortality outcomes, across major psychiatric disorders in Taiwan.

METHOD

A national cohort of adult patients (n = 68,068) who had newly received a diagnosis of schizophrenia, bipolar disorder, and major depressive disorder (MDD) was identified from the National Health Insurance Research Database and followed for the subsequent three years. Variations in the 1-year and 3-year healthcare cost distributions and mortality outcomes were examined according to age group (18-64 years, ≥65 years) and diagnosis.

RESULTS

Regardless of age group, individuals with schizophrenia had the highest total and psychiatric healthcare costs. Healthcare costs for psychiatric services accounted for 84.25%, 60%, and 29.62% of the 1-year total healthcare costs for younger patients with a diagnosis of schizophrenia, bipolar disorder, and MDD, respectively. Psychiatric inpatient care costs constituted a major part of the 1-year psychiatric healthcare costs, e.g., 85.86% for schizophrenia patients aged 18-64 years, while psychiatric medication costs contributed to a relatively smaller part. For those older than 65 years, costs of other specialties for comorbid physical conditions were more prominent.

LIMITATIONS

The perspective of the current analysis was limited to healthcare services, and we were not able to analyse wider economic impacts.

CONCLUSIONS

Psychiatric inpatient care costs contributed to a significant share of psychiatric expenditures, emphasizing the need of developing strategies to reduce rehospitalisations. For those aged 65 years or older, efforts to improve interdisciplinary service care for comorbid physical conditions may be required.

Analysis of the Health Insurance Review and Assessment Service data from 2011 to 2015

Background

Schizophrenia is a recurrent, debilitating disease that is rarely curable. Rapid intervention after the first episode of schizophrenia has been shown to positively affect the prognosis. Unfortunately, basic data is scarce on first-episode schizophrenia in Korean patients making it difficult to create a comprehensive list of risk factors for relapse. This study aims to investigate the demographic characteristics and institutional factors of patients with first-episode schizophrenia in order to identify risk factors for relapse.

Methods

Data from the Health Insurance Review & Assessment Service (HIRA) was used for this study to represent the Korean patient population. To identify factors affecting relapse, we explored gender, age, geographic location, medical benefits, type of medical institution, type of medication used, medication adherence, and the severity of symptoms. Data analysis was performed using the Cox proportional hazard model.

Results

The number of patients diagnosed with first-episode schizophrenia in Korea over a 2-year period was 4567 of which 1265 (27.7%) patients experienced a relapse during the observational period. Factors affecting relapse included age, type of medical institution, type of medication used, medication adherence, and type of treatment (inpatient or outpatient) after the initial diagnosis, which varied depending upon the severity of symptoms.

Conclusions

It was found that environmental and institutional factors as well as the type of medical treatment were crucial in determining whether patients with first-episode schizophrenia subsequently relapsed. The results of this study can be utilized as source material for directing therapeutic interventions and improving mental health policies in the future.

Association of high psychiatrist staffing with prolonged hospitalization, follow-up visits, and readmission in acute psychiatric units: a retrospective cohort study using a nationwide claims database

BACKGROUND

The effects of psychiatrist staffing are unclear. The aim of this study was to assess the association of high psychiatrist staffing with prolonged hospitalization, follow-up visits, and readmission in acute psychiatric units.

METHODS

A retrospective cohort study was conducted using the National Database of Health Insurance Claim Information and Specified Medical Checkups. Patients newly admitted to acute psychiatric units between October 2014 and September 2015 were followed up until September 2016. The primary exposure was a patient-to-psychiatrist ratio of 16:1 (high-staffing units) vs 48:1 (low-staffing units). Outcomes were prolonged hospitalization of >90 days, number of follow-up psychiatric visits within 90 days after discharge, and psychiatric readmission within 90 days after discharge. Incidence rate ratios (IRRs) and their 95% confidence intervals (CIs) were estimated by using generalized estimating equations, adjusting for potential covariates.

RESULTS

Among the 24,678 newly admitted patients at 190 hospitals, 13,138 patients (53.2%) were admitted to high-staffing units in 92 hospitals. After adjustment, high-staffing units were associated with a lower risk of prolonged hospitalization (incidence rate, 16.9 vs 21.3%; IRR, 0.79 [95% CI, 0.70, 0.89]), higher number of follow-up visits (incidence rate of ≥7 visits, 16.9 vs 13.4%; IRR, 1.06 [95% CI, 1.01, 1.12]), and lower risk of readmission (incidence rate, 13.0 vs 14.4%; IRR, 0.90 [95% CI, 0.82, 0.99]).

CONCLUSION

High-staffing units are associated with a reduced risk of prolonged hospitalization and readmission and an increased number of follow-up visits. Further research is needed to improve the generalizability of these findings and establish the optimal level of staffing.

Integrative Review of Mobile Phone Contacts and Medication Adherence in Severe Mental Illness

BACKGROUND

Poor medication adherence is a significant problem in individuals with severe mental illness (SMI). About 50% of people with SMI become nonadherent to treatment in the first month following discharge from the hospital.

OBJECTIVE

This study examined literature in the past decade (2006-2016) on the use of mobile phone contacts in individuals with SMI to improve medication adherence post hospital discharge.

DESIGN

This integrative review used the search terms texting, text messaging, SMS, cell/mobile phone, medication adherence, medication compliance, and mental illness. Databases (CINAHL, PubMed, PsycINFO, and Scopus) and manual searching of reference lists were done. The main inclusion criteria were the use of mobile phone contacts on medication adherence in individuals with SMI. Adults 18 years and older, studies conducted from 2006 to 2016, and studies conducted in English were also criteria for inclusion. Only five studies met criteria for inclusion.

RESULTS

Outcomes from the review showed that mobile phone contacts have been used to improve medication adherence in individuals with SMI and able to provide the four types of social support (instrumental, informational, emotional, and, appraisal). When phone contacts especially text messaging was used as an adjunct to other interventions, it yielded better medication adherence than when used alone. However, results on medication adherence rates were mixed in participants on both psychiatric and nonpsychiatric medications.

CONCLUSION

Although mobile phone contacts are a promising tool to enhance medication adherence after hospital discharge, its effectiveness to increase medication adherence in this population remains inconclusive.

Risk of underdiagnosis of hypertension in schizophrenia patients

AIM

Arterial hypertension requires proper screening and management, and its underdiagnosis in patients with schizophrenia (SZ) and/or antipsychotic treatment has been postulated. The objective of the study is to assess whether there are differences in the proportion of screened patients with a blood pressure >140/90 mmHg that are undiagnosed or not confirmed later (risk of underdiagnosis).

METHODS

Cross-sectional study of clinical records from SIDIAPQ (Spain) during the 2006-2011 period. Three groups were studied: SZ, no SZ but under antipsychotic treatment, and control groups. Patients with established hypertension, cardiovascular disease, dementia, or diagnosis of SZ or starting with antipsychotic treatment during this period were excluded.

RESULTS

The SZ group had a lower risk of underdiagnosis than the control group (OR 0.91; 95% CI: 0.83-0.99; p < 0.05), at the expense of men (OR 0.8; 95% CI: 0.71-0.9; p < 0.001) and patients younger than 50 years of age (OR: 0.84; 95% CI: 0.74-0.93; p < 0.003). In the no SZ but under antipsychotic treatment group there were some differences, but not in the overall results.

CONCLUSION

Preventive management of hypertension seemed to be sufficient for SZ and antipsychotic treatment patients. The lower prevalence of hypertension found in these groups may be due to other factors (blood pressure-lowering effect of psychoactive drugs or smoking) but these hypotheses must be evaluated with specific studies.