Case-control study of medical history and idiopathic pulmonary fibrosis in Japan

Associations Between Diabetes and Idiopathic Pulmonary Fibrosis: a Study-level Pooled Analysis of 26 Million People

CONTEXT

Diabetes mellitus (DM) is a systemic disease characterized by chronic hyperglycemia associated with inflammation and oxidative stress, and the lung may be a target organ of diabetic microvascular damage. Several studies have indicated a positive association between idiopathic pulmonary fibrosis (IPF) and diabetes with controversial findings.

OBJECTIVE

Primary outcomes were to compare the prevalence of DM among individuals with IPF to non-IPF controls, and the prevalence of IPF among individuals with DM to non-DM controls.

METHODS

Data sources include PubMed, EMBASE, and the Cochrane Library. Studies contained sufficient data to calculate the prevalence of DM among individuals with and without IPF, or the prevalence of IPF among individuals with and without DM. Two investigators independently identified eligible studies and extracted data. Pooled odds ratio (OR) with 95% CI was the summary effect measure.

RESULTS

Eighteen studies including 26 410 623 individuals met the eligibility criteria, of whom 16 recruited people with IPF and 2 recruited people with DM. The OR of DM in IPF patients was 1.54 (95% CI, 1.30-1.84; P < .001) compared to that in non-IPF controls. However, compared with that in non-DM patients, the risk of IPF in DM patients was not found to be significantly reduced (OR: 0.89; 95% CI, 0.64-1.25; P = .497).

CONCLUSION

This meta-analysis suggests that people with IPF have 1.54 times increased odds of diabetes compared to non-IPF controls, while whether patients with DM have an increased risk of IPF is still controversial. Further large, prospective cohort studies investigating the prevalence of IPF in diabetic patients are warranted.

The Role of Herpes Viruses in Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a serious lung disease which can result from known genetic or environmental exposures but is more commonly idiopathic (IPF). In familial PF (FPF), the majority of identified causal genes play key roles in the maintenance of telomeres, the protective end structures of chromosomes. Recent evidence suggests that short telomeres may also be implicated causally in a significant proportion of idiopathic cases. The possible involvement of herpes viruses in PF disease incidence and progression has been examined for many years, with some studies showing strong, statistically significant associations and others reporting no involvement. Evidence is thus polarized and remains inconclusive. Here we review the reported involvement of herpes viruses in PF in both animals and humans and present a summary of the evidence to date. We also present several possible mechanisms of action of the different herpes viruses in PF pathogenesis, including potential contributions to telomere attrition and cellular senescence. Evidence for antiviral treatment in PF is very limited but suggests a potential benefit. Further work is required to definitely answer the question of whether herpes viruses impact PF disease onset and progression and to enable the possible use of targeted antiviral treatments to improve clinical outcomes.

Idiopathic pulmonary fibrosis and diabetes mellitus: a meta-analysis and systematic review

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic diffuse interstitial lung disease, of which the etiology has been poorly understood. Several studies have focused on the relationship between IPF and diabetes mellitus (DM) in the past years but have failed to reach a consensus. This meta-analysis aimed to examine the association between diabetes to IPF.

Methods

We accumulated studies investigating the association between DM and IPF from databases including Medline, Cochrane Library, Embase, Web of Science, and China National Knowledge Infrastructure. RevMan 5.3 and the Newcastle–Ottawa Scale (NOS) were utilized to analyze the data and assess the quality of the included studies. The value of odds ratio (OR) with 95% confidence interval (CI) was used as the measure to estimate the risk of DM in IPF. Heterogeneity was assessed by I² statistics. We also performed subgroup analysis, meta-regression, and Egger’s test for bias analysis.

Results

Nine case–control studies with 5096 IPF patients and 19,095 control subjects were included in the present meta-analysis, which indicated a positive correlation between DM and IPF (OR 1.65, 95% CI 1.30–2.10; P < 0.0001). Meta-regression and subgroup analysis negated the influence of covariates like cigarette smoking, age and gender, but the heterogeneity existed and could not be fully explained.

Conclusion

IPF and DM may be associated, but the causal relationship remains indeterminate till now. Further rigorously designed studies are required to confirm the present findings and investigate the possible mechanisms behind the effect of DM on IPF.

The role of viral and bacterial infections in the pathogenesis of IPF: a systematic review and meta-analysis

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease. Several risk factors such as smoking, air pollution, inhaled toxins, high body mass index and infectious agents are involved in the pathogenesis of IPF. In the present study, this meta-analysis study investigates the prevalence of viral and bacterial infections in the IPF patients and any possible association between these infections with pathogenesis of IPF.

Methods

The authors carried out this systematic literature review from different reliable databases such as PubMed, ISI Web of Science, Scopus and Google Scholar to December 2020.Keywords used were the following “Idiopathic pulmonary fibrosis”, “Infection”, “Bacterial Infection” and “Viral Infection”, alone or combined together with the Boolean operators "OR”, “AND” and “NOT” in the Title/Abstract/Keywords field. Pooled proportion and its 95% CI were used to assess the prevalence of viral and bacterial infections in the IPF patients.

Results

In this systematic review and meta-analyses, 32 studies were selected based on the exclusion/inclusion criteria. Geographical distribution of included studies was: eight studies in American people, 8; in European people, 15 in Asians, and one in Africans. The pooled prevalence for viral and bacterial infections w ere 53.72% (95% CI 38.1–69.1%) and 31.21% (95% CI 19.9–43.7%), respectively. The highest and lowest prevalence of viral infections was HSV (77.7% 95% CI 38.48–99.32%), EBV (72.02%, 95% CI 44.65–90.79%) and Influenza A (7.3%, 95% CI 2.66–42.45%), respectively. Whereas the highest and lowest prevalence in bacterial infections were related to Streptococcus sp. (99.49%, 95% CI 96.44–99.9%) and Raoultella (1.2%, 95% CI 0.2–3.08%), respectively.

Conclusions

The results of this review were confirmed that the presence of viral and bacterial infections are the risk factors in the pathogenesis of IPF. In further analyses, which have never been shown in the previous studies, we revealed the geographic variations in the association strengths and emphasized other methodological parameters (e.g., detection method). Also, our study supports the hypothesis that respiratory infection could play a key role in the pathogenesis of IP.

[Differential diagnosis of idiopathic pulmonary fibrosis]

The review is devoted to the urgent problem of modern pulmonology: the differential diagnosis of idiopathic pulmonary fibrosis (ILF). ILF occupies a special place among many interstitial lung diseases for a number of reasons: 1) it is a deadly disease; 2) early diagnosis and adequate antifibrotic therapy significantly extend the life expectancy of patients; 3) anti-inflammatory drugs (corticosteroids) and cytostatics with ILF that are widely used in other forms of interstitial lung diseases are ineffective and accelerate the progression of the process; 4) the commonality of the main clinical signs (increasing respiratory failure) of various interstitial lung diseases. The list of respiratory diseases with which ILF should be differentiated is huge, and if with diffuse lung lesions of a known nature (disseminated pulmonary tuberculosis, pneumoconiosis, etc.) with a certain experience/qualification, the diagnosis is relatively simple, then the isolation of ILF from the group of idiopathic interstitial pneumonias always represents certain difficulties. The main methods used in the diagnosis of ILF are summarized taking into account current international and national recommendations.

Highlights of high-resolution computed tomography imaging in evaluation of complications and co-morbidities in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) represents a condition included in the heterogeneous group of interstitial lung diseases without known causes. The recent ATS/ERS/JRS/ALAT guidelines and the white paper published by the Fleischner Society have well-defined diagnosis and management of idiopathic pulmonary fibrosis. Idiopathic pulmonary fibrosis management is complex because it is also influenced by several co-morbidities and complications. The new frontier in idiopathic pulmonary fibrosis is represented by the effort to understand the complex mechanism of the pathogenesis and progression of disease in order to predict several consequences and co-morbidities. In our review, we tried to distinguish co-morbidities from complications of idiopathic pulmonary fibrosis. In each complication, we have reviewed the existing literature and we have emphasized the complex pathobiological pathway which links the progression of idiopathic pulmonary fibrosis to the development of the complication itself. For every co-morbidity, we tried to identify share common risk factors which explain the coexistence of idiopathic pulmonary fibrosis with its co-morbidities. We then analyzed high-resolution computed tomography (CT) aspects of co-morbidities and complications of idiopathic pulmonary fibrosis that the radiologist should be aware of. In this review, we focused on the role of high-resolution CT imaging in the evaluation of co-morbidities and complications in idiopathic pulmonary fibrosis because their early diagnosis and treatment could change the prognosis in patients with idiopathic pulmonary fibrosis. We have also pointed out that in some cases the final combined quantitative CT tools and conventional visual CT score would allow to get an accurate analysis and quantification of disease progression, co-morbidities, and complications of idiopathic pulmonary fibrosis in order to improve staging systems in idiopathic pulmonary fibrosis.

Viral Infection Increases the Risk of Idiopathic Pulmonary Fibrosis: A Meta-Analysis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic lung disease with a poor prognosis. Although many factors have been identified that possibly trigger or aggravate IPF, such as viral infection, the exact cause of IPF remains unclear. Until now, there has been no systematic review to assess the role of viral infection in IPF quantitatively.

OBJECTIVE

This meta-analysis aims to present a collective view on the relationship between viral infection and IPF.

METHODS

We searched studies reporting the effect of viral infection on IPF in the PubMed, Embase, Cochrane Library, Web of Science, and Wiley Online Library databases. We calculated ORs with 95% CIs to assess the risk of virus in IPF. We also estimated statistical heterogeneity by using I² and Cochran Q tests and publication bias by using the funnel plot, Begg test, Egger test, and trim-and-fill methods. Regression, sensitivity, and subgroup analyses were performed to assess the effects of confounding factors, such as sex and age.

RESULTS

We analyzed 20 case-control studies from 10 countries with 1,287 participants. The pooled OR of all viruses indicated that viral infection could increase the risk of IPF significantly (OR, 3.48; 95% CI, 1.61-7.52; P = .001), but not that of exacerbation of IPF (OR, 0.99; 95% CI, 0.47-2.12; P = .988). All analyzed viruses, including Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus 7 (HHV-7), and human herpesvirus 8 (HHV-8), were associated with a significant elevation in the risk of IPF, except human herpesvirus 6 (HHV-6).

CONCLUSIONS

The presence of persistent or chronic, but not acute, viral infections, including EBV, CMV, HHV-7, and HHV-8, significantly increases the risk of developing IPF, but not exacerbation of IPF. These findings imply that viral infection could be a potential risk factor for IPF.

Diagnosing complications and co-morbidities of fibrotic interstitial lung disease

Introduction: Interstitial lung diseases (ILDs) represent a heterogeneous group of rare disorders that include more than 200 entities, mostly associated with high mortality. In recent years, the progress regarding the understanding of the pathogenesis of these diseases led to the approval of specific treatments. In ILDs, the presence of comorbidities has a significant impact on the quality of life and the survival of patients and, therefore, their diagnosis and treatment has a pivotal role in management and could improve overall outcome. Areas covered: We discuss key diagnostic issues with regard to the most frequent comorbidities in ILDs. Treatment options are also discussed as the decision to investigate more definitively in order to identify specific comorbidities (including lung cancer, pulmonary hypertension, GE reflux, and obstructive sleep apnoea) is critically dependent upon whether comorbidity-specific treatments are likely to be helpful in individual patients, judged on a case by case basis. Expert opinion: The extent to which clinicians proactively pursue the identification of comorbidities depends on realistic treatment goals in individual patients.

Comorbid Conditions in Idiopathic Pulmonary Fibrosis: Recognition and Management

Idiopathic pulmonary fibrosis (IPF), a fibrosing interstitial pneumonia of unknown etiology, primarily affects older adults and leads to a progressive decline in lung function and quality of life. With a median survival of 3-5 years, IPF is the most common and deadly of the idiopathic interstitial pneumonias. Despite the poor survivorship, there exists substantial variation in disease progression, making accurate prognostication difficult. Lung transplantation remains the sole curative intervention in IPF, but two anti-fibrotic therapies were recently shown to slow pulmonary function decline and are now approved for the treatment of IPF in many countries around the world. While the approval of these therapies represents an important first step in combatting of this devastating disease, a comprehensive approach to diagnosing and treating patients with IPF remains critically important. Included in this comprehensive assessment is the recognition and appropriate management of comorbid conditions. Though IPF is characterized by single organ involvement, many comorbid conditions occur within other organ systems. Common cardiovascular processes include coronary artery disease and pulmonary hypertension (PH), while gastroesophageal reflux and hiatal hernia are the most commonly encountered gastrointestinal disorders. Hematologic abnormalities appear to place patients with IPF at increased risk of venous thromboembolism, while diabetes mellitus (DM) and hypothyroidism are prevalent metabolic disorders. Several pulmonary comorbidities have also been linked to IPF, and include emphysema, lung cancer, and obstructive sleep apnea. While the treatment of some comorbid conditions, such as CAD, DM, and hypothyroidism is recommended irrespective of IPF, the benefit of treating others, such as gastroesophageal reflux and PH, remains unclear. In this review, we highlight common comorbid conditions encountered in IPF, discuss disease-specific diagnostic modalities, and review the current state of treatment data for several key comorbidities.

Comorbidities in idiopathic pulmonary fibrosis patients: a systematic literature review

Idiopathic pulmonary fibrosis (IPF) is associated with a fatal prognosis and manifests in patients over 60 years old who may have comorbidities. The prevalence and impact of comorbidities on the clinical course of IPF is unclear.

This systematic literature review examined the prevalence of comorbidities and mortality associated with comorbidities in IPF patients. Relevant observational studies published in English from January 1990 to January 2015 identifiedviaMEDLINE and EMBASE were included; bibliographies of articles were also searched.

Among the 126 studies included, prevalence of pulmonary hypertension (PH) was 3–86%, 6–91% for obstructive sleep apnoea, 3–48% for lung cancer and 6–67% for chronic obstructive pulmonary disease (COPD). Nonrespiratory comorbidities included ischaemic heart disease (IHD) (3–68%) and gastro-oesophageal reflux (GER) (0–94%). Mortality was highest among patients with IPF and lung cancer. Most studies assessed relatively small samples of patients with IPF.

PH, COPD, lung cancer, GER and IHD are significant comorbidities; differences in IPF severity, case definitions and patient characteristics limited the comparability of findings. The identification and prompt treatment of comorbidities may have a clinically significant impact on overall outcome that is meaningful for patients with IPF.

Effects of smoking, gender and occupational exposure on the risk of severe pulmonary fibrosis: a population-based case-control study

OBJECTIVES

To estimate the effects of smoking, gender and occupational exposure on the risk of developing severe pulmonary fibrosis (PF), including dose-response and interaction effects.

METHODS

National case-control study of 171 patients (cases) who had started a long-term oxygen therapy for PF in Sweden between February 1997 and April 2000, and 719 random control participants from the general population. Of these cases, 137 had probable idiopathic PF (IPF). The ORs for smoking, gender and occupational exposure were estimated using Mantel-Haenszel analysis and conditional logistic regression, controlling for age and year of diagnosis.

RESULTS

The adverse effect of smoking was amplified by male gender and occupational exposure, OR 4.6 (95% CI 2.1 to 10.3) for PF, and OR 3.0 (1.3 to 6.5) for IPF, compared with in non-exposed women. Higher cumulative smoking exposure was linearly associated with increased risks. Compared with smoking less than 10 pack-years, smoking ≥20 pack-years was associated with increased risk of PF and IPF, OR 2.6 (1.4 to 4.9) and OR 2.5 (1.3 to 5.0), respectively.

CONCLUSIONS

Smoking has a dose-related association with increased risk of severe PF. Men with a history of smoking and occupational exposure is a particular risk group for developing severe PF.

Idiopathic pulmonary fibrosis--a systematic review on methodology for the collection of epidemiological data

BACKGROUND

Recent studies suggest that the incidence of idiopathic pulmonary fibrosis (IPF) is rising. Accurate epidemiological data on IPF, however, are sparse and the results of previous studies are contradictory. This study was undertaken to gain insight into the various methods used in the epidemiological research of IPF, and to get accurate and comparable data on these different methodologies.

METHODS

A systematic database search was performed in order to identify all epidemiological studies on IPF after the previous guidelines for diagnosis and treatment were published in 2000. Medline (via Pubmed), Science Sitation Index (via Web of Science) and Embase databases were searched for original epidemiological articles published in English in international peer-reviewed journals starting from 2001. After pre-screening and a full-text review, 13 articles were accepted for data abstraction.

RESULTS

Three different methodologies of epidemiological studies were most commonly used, namely: (1) national registry databases, (2) questionnaire-based studies, and (3) analysis of the health care system's own registry databases. The overall prevalence and incidence of IPF varied in these studies between 0.5-27.9/100,000 and 0.22-8.8/100,000, respectively. According to four studies the mortality and incidence of IPF are rising.

CONCLUSIONS

We conclude that there are numerous ways to execute epidemiological research in the field of IPF. This review offers the possibility to compare the different methodologies that have been used, and this information could form a basis for future studies investigating the prevalence and incidence of IPF.

Clinical characteristics of idiopathic pulmonary fibrosis patients with diabetes mellitus: the national survey in Korea from 2003 to 2007

Evidence suggests that diabetes mellitus (DM) is associated with idiopathic pulmonary fibrosis (IPF). According to the new IPF guidelines, high-resolution computed tomography (HRCT) is an essential means of diagnosing IPF. We investigated the relationship between IPF and DM in patients treated between 2003 and 2007. Newly diagnosed IPF patients in large university teaching hospitals in Korea were enrolled from January 2003 to December 2007. We retrospectively analyzed 1,685 patients using the interstitial lung disease (ILD) registry. In total, 299 IPF patients (17.8%) also had DM. The mean age of our subjects was 68.0 ± 9.4 yr. HRCT showed significantly more reticular and honeycomb patterns in IPF patients with DM than in IPF patients without DM (P = 0.014, P = 0.028, respectively). Furthermore, significantly higher incidences of hypertension, cardiovascular diseases, and other malignancies (except lung cancer) were found in IPF patients with DM than in IPF patients without DM. In conclusion, IPF patients with DM are more likely to have the usual interstitial pneumonia (UIP) pattern, including reticular and honeycomb patterns, on HRCT than are those without DM.

Idiopathic pulmonary fibrosis-an epidemiological and pathological review

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease (ILD) affecting the pulmonary interstitium. Other forms of interstitial lung disease exist, and in some cases, an environmental etiology can be delineated. The diagnosis of IPF is typically established by high-resolution CT scan. IPF tends to have a worse prognosis than other forms of ILD. Familial cases of IPF also exist, suggesting a genetic predisposition; telomerase mutations have been observed to occur in familial IPF, which may also explain the increase in IPF with advancing age. Alveolar epithelial cells are believed to be the primary target of environmental agents that have been putatively associated with IPF. These agents may include toxins, viruses, or the autoantibodies found in collagen vascular diseases. The mechanism of disease is still unclear in IPF, but aberrations in fibroblast differentiation, activation, and proliferation may play a role. Epithelial-mesenchymal transition may also be an important factor in the pathogenesis, as it may lead to accumulation of fibroblasts in the lung and a disruption of normal tissue structure. Abnormalities in other components of the immune system, including T cells, B cells, and dendritic cells, as well as the development of ectopic lymphoid tissue, have also been observed to occur in IPF and may play a role in the stimulation of fibrosis that is a hallmark of the disease. It is becoming increasingly clear that the pathogenesis of IPF is indeed a complex and convoluted process that involves numerous cell types and humoral factors.

Risk factors for idiopathic pulmonary fibrosis in a Mexican population. A case-control study

The etiology of idiopathic pulmonary fibrosis (IPF) remains poorly understood, but some studies have suggested that cigarette smoking or other occupational or environmental exposures, diabetes mellitus, or gastroesophageal reflux may play a role. In this study we evaluated the clinical records of a group of 97 consecutive patients with IPF, and 560 patients suffering 5 different respiratory disorders that were examined as controls: asthma (n=111), chronic obstructive pulmonary disease (n=132), squamous cell lung carcinoma (n=118), lung adenocarcinoma (n=101) and patients with otorhinolaryngology problems but without lung disease (n=98). In bivariate analyses male sex, diabetes mellitus and being former cigarette smoker were associated with IPF. After adjusting by these variables, multivariate analysis revealed that type 2 diabetes mellitus [11.3% in IPF patients vs 2.9% in controls, OR=4.3 (95% CI: 1.9-9.8), p<0.0001] was an independent risk factor associated to IPF. Our results provide additional evidence of a putative relationship between DM2 and idiopathic pulmonary fibrosis. Experimental research is necessary for thorough assessment of the pathogenic mechanisms involved in this association.

Role of diabetes mellitus and gastro-oesophageal reflux in the aetiology of idiopathic pulmonary fibrosis

BACKGROUND

The aetiology of idiopathic pulmonary fibrosis remains poorly understood, but recent studies have suggested that diabetes mellitus and gastro-oesophageal reflux may be risk factors.

OBJECTIVE

To test possible associations between diabetes mellitus and gastro-oesophageal reflux with idiopathic pulmonary fibrosis in the general population.

METHODS

We designed a case-control study in the setting of UK general practices contributing data to The Health Improvement Network primary care database (THIN). We selected patients over 40 years of age with a first diagnosis of idiopathic pulmonary fibrosis, and up to 4 controls per case matched by age, gender, and general practice. We estimated odds ratios for exposure to gastro-oesophageal reflux, gout, hypercholesterolaemia and diabetes mellitus using conditional logistic regression. We explored the role of confounding by smoking habit, socio-economic status, and medication with prednisolone.

RESULTS

Amongst our 920 cases we found increased risks of use of insulin (odds ratio (OR) 2.36; 95% confidence interval (CI) 1.46-3.83) and use of ulcer drugs (OR 2.20; 95% CI 1.88-2.58). These were almost unchanged when we excluded cases and controls who had been prescribed prednisolone. We found no association with hypercholesterolaemia or gout, nor with smoking status or socio-economic status.

CONCLUSIONS

The study provides further evidence of an association between idiopathic pulmonary fibrosis and both diabetes mellitus and gastro-oesophageal reflux.