John York - Academia.edu (original) (raw)

Papers by John York

Annals of the Rheumatic Diseases, 1991

Haemophilic arthritis is a relatively rare arthropathy, but several aspects of its management and... more Haemophilic arthritis is a relatively rare arthropathy, but several aspects of its management and pathogenesis are of interest to rheumatologists. Firstly, the number of haemophiliac patients has increased simultaneously with availability of clotting factor. concentrates, and most severely affected patients are likely to have arthritis amenable to prevention or amelioration by approaches familiar to rheumatologists. Secondly, the pathogenesis is unclear, and a further understanding may provide insights into the responses of joint tissues to injury. Thirdly, the histopathology of haemophilic arthritis represents one extreme of changes seen in rheumatoid synovium, and thus haemophilic arthritis may highlight common mechanisms in joint destruction.

Journal of Vascular Surgery, 2009

Introduction: Successful outcome after lower extremity revascularization is usually measured by p... more Introduction: Successful outcome after lower extremity revascularization is usually measured by physician-oriented terms such as graft patency and amputation-free survival. It has been increasingly appreciated that these criteria do not necessarily translate into success from the prospective of the patient. The purpose of this study, therefore, is to retrospectively examine success after lower extremity revascularization for tissue loss using patient-oriented measures and to include patients who underwent both open surgical bypass and endovascular therapy. Methods: Between 1998 and 2005, 677 patients (316 endovascular and 361 open surgery) underwent revascularization for ischemic tissue loss. The method of revascularization (endovascular or open surgery) was left to the discretion of the surgeon. Revascularization was considered to be clinically successful if each of the following occurred: reconstruction patency until wound healing, limb salvage for 1 year, maintenance of ambulation for 1 year, and survival for 6 months. The influence of 20 intrinsic patient factors, including type of revascularization (open vs endo) was examined using the 2 test. Significant factors in bivariate analysis were included in a logistic regression model to determine independent predictors and probability of failure. Results: Overall clinical success was achieved in 277 (40.9%) patients. Success for open surgical and endovascular cohorts was 44.3% and 37.0%, respectively (P ‫؍‬ .06). Type of intervention was not a significant factor in either bivariate or logistic regression analysis. Independent predictors of failure (odds ratio [OR]; 95% confidence interval [CI]) regardless of treatment type included impaired ambulatory status at the time of presentation (OR 3.24; CI 2.14, 4.90), diabetes (OR 1.62; CI 1.14, 2.32), endstage renal disease (ESRD) (OR 1.55; CI 1.07, 2.23), presence of gangrene (OR 2.0; CI 1.42, 2.82), and prior vascular intervention (OR 1.46; CI 1.02, 2.10). Paradoxically, hyperlipidemia (OR 0.70; CI 0.50, 0.98) was a predictor for success. Probability of failure was 35.4% (OR 1.0) if no independent predictors were present and increased with the addition of each adverse predictor. For instance, diabetic patients with impaired ambulatory status and gangrene had an 85.2% (OR 10.5) probability of failure. In the worst case scenario, a diabetic patient with ESRD, impaired ambulatory status, gangrene, and a prior vascular intervention was considered, probability of failure was a dismal 92.8% (OR 23.7). Conclusion: Clinical success after lower extremity revascularization for ischemic tissue loss is determined by intrinsic patient factors and not by method of revascularization. These data reiterate that future investigation efforts should be focused less on the method of revascularization and more on identification of patient cohorts at risk for failure regardless of treatment.

Clinical Journal of Pain, 2009

The Medical journal of Australia, Jan 16, 1971

Baillière's clinical rheumatology, 1991

The management of the haemophilias has been improved by the advent of potent consistent clotting ... more The management of the haemophilias has been improved by the advent of potent consistent clotting factor replacement therapy. The previously lethal major complications such as intracerebral haemorrhage are now rare, and the infective complications of treatment, most notably hepatitis and AIDS, are now potentially preventable with the new synthetic products. There is also the prospect of 'cure' by gene insertion therapy. Advanced arthropathy has been minimized but not prevented by early effective treatment of haemarthroses, and there is a diminishing legacy of severely affected patients many of whom may require joint replacement surgery. The present group of such patients has a high prevalence of HIV-1 infection and an increased risk of joint sepsis. The available avenues of treatment for the subacute stage of the arthropathy have not been particularly effective, emphasizing the need to prevent recurrent bleeding. The development of a multidisciplinary team-management approach...

BMC musculoskeletal disorders, Jan 22, 2006

Clinical guidelines generally portray acute low back pain as a benign and self-limiting condition... more Clinical guidelines generally portray acute low back pain as a benign and self-limiting condition. However, evidence about the clinical course of acute low back pain is contradictory and the risk of subsequently developing chronic low back pain remains uncertain. There are few high quality prognosis studies and none that have measured pain, disability and return to work over a 12 month period. This study aims to provide the first estimates of the one year prognosis of acute low back pain (pain of less than 2 weeks duration) in patients consulting primary care practitioners. A secondary aim is to identify factors that are associated with the prognosis of low back pain. The study is a prospective inception cohort study. Consecutive patients consulting general medical practitioners, physiotherapists and chiropractors in the Sydney metropolitan region will complete a baseline questionnaire regarding their back pain. Subsequently these patients will be followed up by telephone 6 weeks, 3...

The Journal of Bone and Joint Surgery, 2001

J oint replacement in HIV-positive patients remains uncommon, with most experience gained in pati... more J oint replacement in HIV-positive patients remains uncommon, with most experience gained in patients with haemophilia. We analysed retrospectively the outcome of 102 replacement arthroplasties in 73 HIV-positive patients from eight specialist haemophilia centres. Of these, 91 were primary procedures. The mean age of the patients at surgery was 39 years, and the median follow-up was for five years. The overall rate of deep sepsis was 18.7% for primary procedures and 36.3% for revisions. This is a much higher rate of infection than that seen in normal populations. A total of 44% of infections resolved fully after medical and/or surgical treatment. The benefits of arthroplasty in haemophilic patients are well established but the rates of complications are high. As this large study has demonstrated, high rates of infection occur, but survivorship analysis strongly suggests that most patients already diagnosed with HIV infection at the time of surgery should derive many years of symptomatic relief after a successful joint replacement. Careful counselling and education of both patients and healthcare workers before operation are therefore essential.

The Clinical Journal of Pain, 2009

This study aimed to provide a comprehensive profile of a representative sample of patients with a... more This study aimed to provide a comprehensive profile of a representative sample of patients with acute low back pain drawn from the primary care setting. A secondary aim was to determine whether patient characteristics are associated with pain intensity or disability at the initial consultation. A total of 1172 consecutive patients with acute low back pain presenting to clinics of primary care practitioners (general practitioners, physiotherapists, and chiropractors) in Australia were recruited. Pain intensity and level of disability were measured at the first consultation, and a range of other variables were measured to describe the patient's characteristics. The characteristics were then grouped into 7 distinct factors: demographic, social, cultural, general health, psychologic, past low back pain history, and current low back pain history. Hierarchical linear regression models were used to determine each factor's independent relationship with pain intensity and disability. The majority of patients reported having had a previous episode of low back pain (75.7%), and that the current episode was of sudden onset (76.7%). Only a small proportion (14.3%) had compensable back pain. Pain intensity and disability were associated with each other (P<0.01), current low back pain history (P<0.01), and psychologic (P<0.01) characteristics. In a representative sample of acute low back pain patients in primary care, we found that the profile included only a small proportion of patients with compensable low back pain. Those without compensation were more likely to remain at work despite low back pain. Psychologic and other patient characteristics were associated with pain intensity and level of disability at the initial consultation.

BMJ, 2008

Objective To estimate the one year prognosis and identify prognostic factors in cases of recent o... more Objective To estimate the one year prognosis and identify prognostic factors in cases of recent onset low back pain managed in primary care. Design Cohort study with one year follow-up. Setting Primary care clinics in Sydney, Australia. Participants An inception cohort of 973 consecutive primary care patients (mean age 43.3, 54.8% men) with non-specific low back pain of less than two weeks' duration recruited from the clinics of 170 general practitioners, physiotherapists, and chiropractors. Main outcome measures Participants completed a baseline questionnaire and were contacted six weeks, three months, and 12 months after the initial consultation. Recovery was assessed in terms of return to work, return to function, and resolution of pain. The association between potential prognostic factors and time to recovery was modelled with Cox regression. Results The follow-up rate over the 12 months was more than 97%. Half of those who reduced their work status at baseline had returned to previous work status within 14 days (95% confidence interval 11 to 17 days) and 83% had returned to previous work status by three months. Disability (median recovery time 31 days, 25 to 37 days) and pain (median 58 days, 52 to 63 days) took much longer to resolve. Only 72% of participants had completely recovered 12 months after the baseline consultation. Older age, compensation cases, higher pain intensity, longer duration of low back pain before consultation, more days of reduced activity because of lower back pain before consultation, feelings of depression, and a perceived risk of persistence were each associated with a longer time to recovery. Conclusions In this cohort of patients with acute low back pain in primary care, prognosis was not as favourable as claimed in clinical practice guidelines. Recovery was slow for most patients. Nearly a third of patients did not recover from the presenting episode within a year.

Arthritis & Rheumatism, 2009

To determine the prevalence of serious pathology in patients presenting to primary care settings ... more To determine the prevalence of serious pathology in patients presenting to primary care settings with acute low back pain, and to evaluate the diagnostic accuracy of recommended "red flag" screening questions. An inception cohort of 1,172 consecutive patients receiving primary care for acute low back pain was recruited from primary care clinics in Sydney, Australia. At the initial consultation, clinicians recorded responses to 25 red flag questions and then provided an initial diagnosis. The reference standard was a 12-month followup supplemented with a specialist review of a random subsample of participants. There were 11 cases (0.9%) of serious pathology, including 8 cases of fracture. Despite the low prevalence of serious pathology, most patients (80.4%) had at least 1 red flag (median 2, interquartile range 1-3). Only 3 of the red flags for fracture recommended for use in clinical guidelines were informative: prolonged use of corticosteroids, age >70 years, and significant trauma. Clinicians identified 5 of the 11 cases of serious pathology at the initial consultation and made 6 false-positive diagnoses. The status of a diagnostic prediction rule containing 4 features (female sex, age >70 years, significant trauma, and prolonged use of corticosteroids) was moderately associated with the presence of fracture (the area under the curve for the rule score was 0.834 [95% confidence interval 0.654-1.014]; P = 0.001). In patients presenting to a primary care provider with back pain, previously undiagnosed serious pathology is rare. The most common serious pathology observed was vertebral fracture. Approximately half of the cases of serious pathology were identified at the initial consultation. Some red flags have very high false-positive rates, indicating that, when used in isolation, they have little diagnostic value in the primary care setting.

Annals of the Rheumatic Diseases, 1991

Haemophilic arthritis is a relatively rare arthropathy, but several aspects of its management and... more Haemophilic arthritis is a relatively rare arthropathy, but several aspects of its management and pathogenesis are of interest to rheumatologists. Firstly, the number of haemophiliac patients has increased simultaneously with availability of clotting factor. concentrates, and most severely affected patients are likely to have arthritis amenable to prevention or amelioration by approaches familiar to rheumatologists. Secondly, the pathogenesis is unclear, and a further understanding may provide insights into the responses of joint tissues to injury. Thirdly, the histopathology of haemophilic arthritis represents one extreme of changes seen in rheumatoid synovium, and thus haemophilic arthritis may highlight common mechanisms in joint destruction.

Journal of Vascular Surgery, 2009

Introduction: Successful outcome after lower extremity revascularization is usually measured by p... more Introduction: Successful outcome after lower extremity revascularization is usually measured by physician-oriented terms such as graft patency and amputation-free survival. It has been increasingly appreciated that these criteria do not necessarily translate into success from the prospective of the patient. The purpose of this study, therefore, is to retrospectively examine success after lower extremity revascularization for tissue loss using patient-oriented measures and to include patients who underwent both open surgical bypass and endovascular therapy. Methods: Between 1998 and 2005, 677 patients (316 endovascular and 361 open surgery) underwent revascularization for ischemic tissue loss. The method of revascularization (endovascular or open surgery) was left to the discretion of the surgeon. Revascularization was considered to be clinically successful if each of the following occurred: reconstruction patency until wound healing, limb salvage for 1 year, maintenance of ambulation for 1 year, and survival for 6 months. The influence of 20 intrinsic patient factors, including type of revascularization (open vs endo) was examined using the 2 test. Significant factors in bivariate analysis were included in a logistic regression model to determine independent predictors and probability of failure. Results: Overall clinical success was achieved in 277 (40.9%) patients. Success for open surgical and endovascular cohorts was 44.3% and 37.0%, respectively (P ‫؍‬ .06). Type of intervention was not a significant factor in either bivariate or logistic regression analysis. Independent predictors of failure (odds ratio [OR]; 95% confidence interval [CI]) regardless of treatment type included impaired ambulatory status at the time of presentation (OR 3.24; CI 2.14, 4.90), diabetes (OR 1.62; CI 1.14, 2.32), endstage renal disease (ESRD) (OR 1.55; CI 1.07, 2.23), presence of gangrene (OR 2.0; CI 1.42, 2.82), and prior vascular intervention (OR 1.46; CI 1.02, 2.10). Paradoxically, hyperlipidemia (OR 0.70; CI 0.50, 0.98) was a predictor for success. Probability of failure was 35.4% (OR 1.0) if no independent predictors were present and increased with the addition of each adverse predictor. For instance, diabetic patients with impaired ambulatory status and gangrene had an 85.2% (OR 10.5) probability of failure. In the worst case scenario, a diabetic patient with ESRD, impaired ambulatory status, gangrene, and a prior vascular intervention was considered, probability of failure was a dismal 92.8% (OR 23.7). Conclusion: Clinical success after lower extremity revascularization for ischemic tissue loss is determined by intrinsic patient factors and not by method of revascularization. These data reiterate that future investigation efforts should be focused less on the method of revascularization and more on identification of patient cohorts at risk for failure regardless of treatment.

Clinical Journal of Pain, 2009

The Medical journal of Australia, Jan 16, 1971

Baillière's clinical rheumatology, 1991

The management of the haemophilias has been improved by the advent of potent consistent clotting ... more The management of the haemophilias has been improved by the advent of potent consistent clotting factor replacement therapy. The previously lethal major complications such as intracerebral haemorrhage are now rare, and the infective complications of treatment, most notably hepatitis and AIDS, are now potentially preventable with the new synthetic products. There is also the prospect of 'cure' by gene insertion therapy. Advanced arthropathy has been minimized but not prevented by early effective treatment of haemarthroses, and there is a diminishing legacy of severely affected patients many of whom may require joint replacement surgery. The present group of such patients has a high prevalence of HIV-1 infection and an increased risk of joint sepsis. The available avenues of treatment for the subacute stage of the arthropathy have not been particularly effective, emphasizing the need to prevent recurrent bleeding. The development of a multidisciplinary team-management approach...

BMC musculoskeletal disorders, Jan 22, 2006

Clinical guidelines generally portray acute low back pain as a benign and self-limiting condition... more Clinical guidelines generally portray acute low back pain as a benign and self-limiting condition. However, evidence about the clinical course of acute low back pain is contradictory and the risk of subsequently developing chronic low back pain remains uncertain. There are few high quality prognosis studies and none that have measured pain, disability and return to work over a 12 month period. This study aims to provide the first estimates of the one year prognosis of acute low back pain (pain of less than 2 weeks duration) in patients consulting primary care practitioners. A secondary aim is to identify factors that are associated with the prognosis of low back pain. The study is a prospective inception cohort study. Consecutive patients consulting general medical practitioners, physiotherapists and chiropractors in the Sydney metropolitan region will complete a baseline questionnaire regarding their back pain. Subsequently these patients will be followed up by telephone 6 weeks, 3...

The Journal of Bone and Joint Surgery, 2001

J oint replacement in HIV-positive patients remains uncommon, with most experience gained in pati... more J oint replacement in HIV-positive patients remains uncommon, with most experience gained in patients with haemophilia. We analysed retrospectively the outcome of 102 replacement arthroplasties in 73 HIV-positive patients from eight specialist haemophilia centres. Of these, 91 were primary procedures. The mean age of the patients at surgery was 39 years, and the median follow-up was for five years. The overall rate of deep sepsis was 18.7% for primary procedures and 36.3% for revisions. This is a much higher rate of infection than that seen in normal populations. A total of 44% of infections resolved fully after medical and/or surgical treatment. The benefits of arthroplasty in haemophilic patients are well established but the rates of complications are high. As this large study has demonstrated, high rates of infection occur, but survivorship analysis strongly suggests that most patients already diagnosed with HIV infection at the time of surgery should derive many years of symptomatic relief after a successful joint replacement. Careful counselling and education of both patients and healthcare workers before operation are therefore essential.

The Clinical Journal of Pain, 2009

This study aimed to provide a comprehensive profile of a representative sample of patients with a... more This study aimed to provide a comprehensive profile of a representative sample of patients with acute low back pain drawn from the primary care setting. A secondary aim was to determine whether patient characteristics are associated with pain intensity or disability at the initial consultation. A total of 1172 consecutive patients with acute low back pain presenting to clinics of primary care practitioners (general practitioners, physiotherapists, and chiropractors) in Australia were recruited. Pain intensity and level of disability were measured at the first consultation, and a range of other variables were measured to describe the patient's characteristics. The characteristics were then grouped into 7 distinct factors: demographic, social, cultural, general health, psychologic, past low back pain history, and current low back pain history. Hierarchical linear regression models were used to determine each factor's independent relationship with pain intensity and disability. The majority of patients reported having had a previous episode of low back pain (75.7%), and that the current episode was of sudden onset (76.7%). Only a small proportion (14.3%) had compensable back pain. Pain intensity and disability were associated with each other (P<0.01), current low back pain history (P<0.01), and psychologic (P<0.01) characteristics. In a representative sample of acute low back pain patients in primary care, we found that the profile included only a small proportion of patients with compensable low back pain. Those without compensation were more likely to remain at work despite low back pain. Psychologic and other patient characteristics were associated with pain intensity and level of disability at the initial consultation.

BMJ, 2008

Objective To estimate the one year prognosis and identify prognostic factors in cases of recent o... more Objective To estimate the one year prognosis and identify prognostic factors in cases of recent onset low back pain managed in primary care. Design Cohort study with one year follow-up. Setting Primary care clinics in Sydney, Australia. Participants An inception cohort of 973 consecutive primary care patients (mean age 43.3, 54.8% men) with non-specific low back pain of less than two weeks' duration recruited from the clinics of 170 general practitioners, physiotherapists, and chiropractors. Main outcome measures Participants completed a baseline questionnaire and were contacted six weeks, three months, and 12 months after the initial consultation. Recovery was assessed in terms of return to work, return to function, and resolution of pain. The association between potential prognostic factors and time to recovery was modelled with Cox regression. Results The follow-up rate over the 12 months was more than 97%. Half of those who reduced their work status at baseline had returned to previous work status within 14 days (95% confidence interval 11 to 17 days) and 83% had returned to previous work status by three months. Disability (median recovery time 31 days, 25 to 37 days) and pain (median 58 days, 52 to 63 days) took much longer to resolve. Only 72% of participants had completely recovered 12 months after the baseline consultation. Older age, compensation cases, higher pain intensity, longer duration of low back pain before consultation, more days of reduced activity because of lower back pain before consultation, feelings of depression, and a perceived risk of persistence were each associated with a longer time to recovery. Conclusions In this cohort of patients with acute low back pain in primary care, prognosis was not as favourable as claimed in clinical practice guidelines. Recovery was slow for most patients. Nearly a third of patients did not recover from the presenting episode within a year.

Arthritis & Rheumatism, 2009

To determine the prevalence of serious pathology in patients presenting to primary care settings ... more To determine the prevalence of serious pathology in patients presenting to primary care settings with acute low back pain, and to evaluate the diagnostic accuracy of recommended "red flag" screening questions. An inception cohort of 1,172 consecutive patients receiving primary care for acute low back pain was recruited from primary care clinics in Sydney, Australia. At the initial consultation, clinicians recorded responses to 25 red flag questions and then provided an initial diagnosis. The reference standard was a 12-month followup supplemented with a specialist review of a random subsample of participants. There were 11 cases (0.9%) of serious pathology, including 8 cases of fracture. Despite the low prevalence of serious pathology, most patients (80.4%) had at least 1 red flag (median 2, interquartile range 1-3). Only 3 of the red flags for fracture recommended for use in clinical guidelines were informative: prolonged use of corticosteroids, age >70 years, and significant trauma. Clinicians identified 5 of the 11 cases of serious pathology at the initial consultation and made 6 false-positive diagnoses. The status of a diagnostic prediction rule containing 4 features (female sex, age >70 years, significant trauma, and prolonged use of corticosteroids) was moderately associated with the presence of fracture (the area under the curve for the rule score was 0.834 [95% confidence interval 0.654-1.014]; P = 0.001). In patients presenting to a primary care provider with back pain, previously undiagnosed serious pathology is rare. The most common serious pathology observed was vertebral fracture. Approximately half of the cases of serious pathology were identified at the initial consultation. Some red flags have very high false-positive rates, indicating that, when used in isolation, they have little diagnostic value in the primary care setting.