Loss to follow-up: does it matter?

Factors associated with non-participation and dropout among cancer patients in a cluster-randomised controlled trial

We investigated the impact of demographic and disease related factors on non-participation and dropout in a cluster-randomised behavioural trial in cancer patients with measurements taken between hospitalisation and 6 months thereafter. The percentages of non-participation and dropout were documented at each time point. Factors considered to be potentially related with non-participation and dropout were as follows: age, sex, marital status, education, income, employment status, tumour site and stage of disease. Of 1,338 eligible patients, 24% declined participation at baseline. Non-participation was higher in older patients (Odds Ratio [OR] 2.1, CI: 0.6-0.9) and those with advanced disease (OR 2.0, CI: 0.1-1.3). Dropout by 6 months was 25%. Dropout was more frequent with increased age (OR 2.8, CI: 0.8-1.2), advanced disease (OR 3.0, CI: 1.0-1.2), being married (OR 2.4, CI 0.7-1.1) and less frequent with university education (OR 0.4, CI -1.3 to -0.8) and middle income (OR 0.4, CI -0.9 to -0.7). When planning clinical trials, it is important to be aware of patient groups at high risk of non-participation or dropout, for example older patients or those with advanced disease. Trial designs should consider their special needs to increase their rate of participation.

Midterm Outcomes of Revision Total Hip Arthroplasty Using a Modular Revision Hip System

BACKGROUND

The growth in hip arthroplasty surgery has meant a corresponding escalating revision burden with increasing challenges for the orthopaedic surgeon. The purpose of this study was to review clinical outcomes of a modular revision hip system within a single institution.

METHODS

We retrospectively reviewed a cohort of modular revision hip system stems performed in our institution between January 2005 and October 2012 giving a potential minimum follow-up of 2 years. Clinical outcomes data on complications, Oxford Hip Score (OHS, 0-48) and patient satisfaction were collected. Radiographic outcomes including subsidence were assessed. Implant survival was estimated using Kaplan Meier analysis.

RESULTS

115 stems in 106 patients were identified. All cause survival was 82% (95%CIs: 73%-89%) at 6.1 years; survival excluding infection being 99% (95%CIs: 93%-100%). There was a low incidence of subsidence (seven stems) and no peri-prosthetic fractures. Primary cause of re-revision in this series was re-infection with only one re-revision for mechanical failure. Median Oxford Hip Score at mean follow up 4.1 years (2-9) was 40 (14-48) and 93% of patients reported being satisfied with their revision surgery.

CONCLUSION

This study showed good clinical outcomes and survival using a modular revision stem with low mechanical failure and subsidence. Recurrence of infection remains a challenge in revision surgery.

Survivorship and Complications of Revision Total Hip Arthroplasty with a Mid-Modular Femoral Stem

We retrospectively reviewed 161 revision THAs with diaphyseal fitting, mid-modular femoral components performed by ten surgeons at two academic medical centers. The average follow-up was 6.1 years. At final follow-up, 4 patients required re-revision for failure of the femoral component; 3 (2%) for aseptic loosening and 1 for mechanical failure of stem in setting of periprosthetic fracture. There were a total of 24 (14.9%) revisions for any reason, with the most common reason being septic failure (10 of 24). To our knowledge, this is the largest reported series of mid-term survivorship and complications of revision THA with mid-modular femoral components. Our results show that these stems have a low rate of aseptic loosening, subsidence, and mechanical failure.

Revision total hip arthroplasty with modular femoral stems

As the rate of revision total hip arthroplasty (THA) rises, attention must be paid to potential complications relating to bone loss, soft tissue deficiencies, and loss of tissue planes. Using modular femoral stems in revision surgery allows for varying amounts of bone loss in the proximal and distal femur while letting the surgeon adjust rotation, leg length, and offset. We retrospectively reviewed 125 patients that underwent revision THA with a modular femoral component system and had minimum 2 year follow-up. Ten patients required reoperations for infection, recurrent dislocation, or fracture treatment. There was no evidence of radiographic loosening or mechanical failure in the remaining patients. Modular femoral components provide excellent intraoperative flexibility and significant radiographic and clinical benefits as seen in this patient cohort.

10-year results of the uncemented Allofit press-fit cup in young patients

BACKGROUND AND PURPOSE

Uncemented acetabular components in primary total hip arthroplasty (THA) are commonly used today, but few studies have evaluated their survival into the second decade in young and active patients. We report on a minimum 10-year follow-up of an uncemented press-fit acetabular component that is still in clinical use.

METHODS

We examined the clinical and radiographic results of our first 121 consecutive cementless THAs using a cementless, grit-blasted, non-porous, titanium alloy press-fit cup (Allofit; Zimmer Inc., Warsaw, IN) without additional screw fixation in 116 patients. Mean age at surgery was 51 (21-60) years. Mean time of follow-up evaluation was 11 (10-12) years.

RESULTS

At final follow-up, 8 patients had died (8 hips), and 1 patient (1 hip) was lost to follow-up. 3 hips in 3 patients had undergone acetabular revision, 2 for deep infection and 1 for aseptic acetabular loosening. There were no impending revisions at the most recent follow-up. We did not detect periacetabular osteolysis or loosening on plain radiographs in those hips that were evaluated radiographically (n = 90; 83% of the hips available at a minimum of 10 years). Kaplan-Meier survival analysis using revision of the acetabular component for any reason (including isolated inlay revisions) as endpoint estimated the 11-year survival rate at 98% (95% CI: 92-99).

INTERPRETATION

Uncemented acetabular fixation using the Allofit press-fit cup without additional screws was excellent into early in the second decade in this young and active patient cohort. The rate of complications related to the liner and to osteolysis was low.

Recruitment, retention, and blinding in clinical trials

The recruitment and retention of participants and the blinding of participants, health care providers, and data collectors present challenges for clinical trial investigators. This article reviews challenges and alternative strategies associated with these three important clinical trial activities. Common recruiting pitfalls, including low sample size, unfriendly study designs, suboptimal testing locations, and untimely recruitment are discussed together with strategies for overcoming these barriers. The use of active controls, technology-supported visit reminders, and up-front scheduling is recommended to prevent attrition and maximize retention of participants. Blinding is conceptualized as the process of concealing research design elements from key players in the research process. Strategies for blinding participants, health care providers, and data collectors are suggested.

Attrition in longitudinal randomized controlled trials: home visits make a difference

Background

Participant attrition in longitudinal studies can introduce systematic bias, favoring participants who return for follow-up, and increase the likelihood that those with complications will be underestimated. Our aim was to examine the effectiveness of home follow-up (Home F/U) to complete the final study evaluation on potentially “lost” participants by: 1) evaluating the impact of including and excluding potentially “lost” participants (e.g., those who required Home F/U to complete the final evaluation) on the rates of study complications; 2) examining the relationship between timing and number of complications on the requirement for subsequent Home F/U; and 3) determining predictors of those who required Home F/U.

Methods

We used data from a randomized controlled trial (RCT) conducted from 1991–1994 among coronary artery bypass graft surgery patients that investigated the effect of High mean arterial pressure (MAP) (intervention) vs. Low MAP (control) during cardiopulmonary bypass on 5 complications: cardiac morbidity/mortality, neurologic morbidity/mortality, all-cause mortality, neurocognitive dysfunction and functional decline. We enhanced completion of the final 6-month evaluation using Home F/U.

Results

Among 248 participants, 61 (25%) required Home F/U and the remaining 187 (75%) received Routine F/U. By employing Home F/U, we detected 11 additional complications at 6 months: 1 major neurologic complication, 6 cases of neurocognitive dysfunction and 4 cases of functional decline. Follow-up of 61 additional Home F/U participants enabled us to reach statistical significance on our main trial outcome. Specifically, the High MAP group had a significantly lower rate of the Combined Trial Outcome compared to the Low MAP group, 16.1% vs. 27.4% (p=0.032). In multivariate analysis, participants who were ≥ 75 years (OR=3.23, 95% CI 1.52-6.88, p=0.002) or on baseline diuretic therapy (OR=2.44, 95% CI 1.14-5.21, p=0.02) were more likely to require Home F/U. In addition, those in the Home F/U group were more likely to have sustained 2 or more complications (p=0.05).

Conclusions

Home visits are an effective approach to reduce attrition and improve accuracy of study outcome reporting. Trial results may be influenced by this method of reducing attrition. Older participants, those with greater medical burden and those who sustain multiple complications are at higher risk for attrition.

Adding more muscle and nerve to clinical trials

In this review we illustrate both the fundamentals and challenges of randomized clinical trials in neuromuscular disorders and suggest directions for prospective efforts to improve the design, conduct, rigor, and objectivity of these trials. Current research in clinical trials for neuromuscular disorders and key issues affecting these trials are reviewed. This perspective addresses the planning of clinical research, level of preclinical data needed to justify trials, patient recruitment and retention, and opportunities to access federal funding and infrastructure in support of clinical trials. The need for innovation in trial design and conduct, rigorous standards for the preclinical efficacy and safety data that support trial rationale, novel collaborative paradigms, objective interpretations of outcomes, and sharing of the lessons learned from trials in any one disorder among all neuromuscular trialists are imperative to improving the heretofore limited success in delivering novel, safe, and effective therapies to patients burdened by neuromuscular disorders.

Prospective study of a cementless total hip arthroplasty with a collum femoris preserving stem and a trabeculae oriented pressfit cup: minimun 6-year follow-up

AIM

Tissue sparing hip prostheses are becoming more and more popular especially for the treatment of younger patients. The objective of this study was to evaluate the clinical and radiological results after insertion of a tissue sparing hip prosthesis.

METHOD

In 47 consecutive non-selected patients (50 hips), the clinical and radiographic results of cementless total hip arthroplasty using a collum femoris preserving stem, a pressfit cup and an alumina-polyethylene pairing were prospectively evaluated. The mean age at index-surgery was 58 (36-82) years, there were 38 women and 9 men. After a mean follow-up of 6.8 years (minimum 6.1 years), two patients had died and one patient underwent revision surgery due to aseptic loosening of the stem.

RESULTS

The overall survival rate of the acetabular component was 100% and of the femoral component 98%. The mean Harris hip score at follow-up was 94 points.

CONCLUSION

The mid-term survival with this type of total hip arthroplasty is excellent and compares equal with uncemented straight stems in this age group.

Minimum 5-year follow-up of a cementless, modular, tapered stem in hip revision arthroplasty

Hip revision surgery with a cementless tapered femoral component can provide axial and rotational stability in patients with compromised proximal bone stock. This study includes 90 cases revised with the Link MP (Waldemar Link, Hamburg, Germany) prosthesis. The median age at surgery was 72 (38-89) years. Aseptic loosening (70%) and periprosthetic fracture (22%) were common indications for surgery. Sixty-three patients (70%) were followed clinically with a median of 6 (5-11) years of follow-up. All other patients were followed through the Swedish Hip Register. The 5-year survival rate was 98% with stem removal and 90% with any reoperation as the end point. Complications included hip dislocation in 17 (19%) patients. The median Harris hip score was 78 (16-100) points, and the median radiographic stem migration was 2.7 mm at follow-up.

Recruitment and retention of patients into emergency medicine clinical trials

The emergency medicine (EM) and prehospital environments are unlike any other clinical environments and require special consideration to allow the successful implementation of clinical trials. This article reviews the specific issues involved in EM clinical trials and provides strategies from EM and non-EM trials to maximize recruitment and retention. While the evidence supporting some of these strategies is deficient, addressing recruitment and retention issues with specific strategies will help researchers deal with these issues in their funding applications and in turn develop the necessary infrastructure to participate in EM clinical trials.

Survival of the cementless Spotorno stem in the second decade

High survival rates have been reported for the uncemented CLS Spotorno stem up to 10 years. To confirm survival at longer followup we report the minimum 15-year (mean, 17 years; range, 15-20 years) for 257 hips using this stem. We retrospectively evaluated the clinical and radiographic results of all 326 patients (354 THAs) operated between 1985 and 1989. The patients had a mean age of 57 years using an uncemented grit-blasted, tapered titanium femoral stem. Eighty-six patients (89 hips) died and eight patients (eight hips) were lost to followup, leaving 240 patients (257 hips) for evaluation. The femoral component was revised in 35 hips: eight for infection, nine for periprosthetic fracture, one for traumatic loosening, and 17 for aseptic loosening. Survival of the stem was 88% at 17 years (95% confidence interval, 84%-92%), and survival with femoral revision for aseptic loosening as an end point was 94% (95% confidence interval, 91%-97%). The median Harris hip score at followup was 80 points. No thigh pain was reported. Small osteolytic lesions (< 1 cm(2)) were found in the proximal Gruen zones (1 or/and 7) in 28 hips (15%). No distal femoral osteolysis was found. The long-term survival with this type of femoral component remains high in the second decade.

Acetabular bone reconstruction in revision arthroplasty: a comparison of freeze-dried, irradiated and chemically-treated allograft vitalised with autologous marrow versus frozen non-irradiated allograft

Deficiencies of acetabular bone stock at revision hip replacement were reconstructed with two different types of allograft using impaction bone grafting and a Burch-Schneider reinforcement ring. We compared a standard frozen non-irradiated bone bank allograft (group A) with a freeze-dried irradiated bone allograft, vitalised with autologous marrow (group B). We studied 78 patients (79 hips), of whom 87% (69 hips) had type III acetabular defects according to the American Academy of Orthopaedic Surgeons classification at a mean of 31.4 months (14 to 51) after surgery. At the latest follow-up, the mean Harris hip score was 69.9 points (13.5 to 97.1) in group A and 71.0 points (11.5 to 96.5) in group B. Each hip showed evidence of trabeculation and incorporation of the allograft with no acetabular loosening. These results suggest that the use of an acetabular reinforcement ring and a living composite of sterile allograft and autologous marrow appears to be a method of reconstructing acetabular deficiencies which gives comparable results to current forms of treatment.

Loss to follow up did not bias associations between early life factors and adult depression

OBJECTIVE

This study examines the consequences of nonresponse in a follow-up survey for the associations of early life factors with adult depression.

STUDY DESIGN AND SETTING

A cohort of 11,532 Danish men born in 1953 had nearly complete follow up for outcomes retrieved from the Danish Psychiatric Register and the National Prescription Register, but only 66% of 9,507 eligible cohort members participated in a follow-up survey in 2004. We examined whether characteristics measured at birth and at ages 12 and 18 years, were associated with survey response. Associations between early life characteristics and four measures of depression were described by odd ratios (OR), estimated by logistic regression. For the register-based measures the effect of nonresponse was described by a relative OR(OR(responders)/OR(entire cohort)=ROR).

RESULTS

Nonresponse at 50 years of age was related to having a single mother at birth, low educational attainment at age 18, and low cognitive function at ages 12 and 18. Hospitalizations for depression and having claimed a prescription for an antidepressive drug were also most frequent among men who did not respond in the follow up. However, the effect of this nonresponse on the estimated ORs was small, and all ROR were nonsignificant.

CONCLUSION

Although early life characteristics were related to response in a follow-up survey, the ORs for the exposure-risk associations were not biased by nonresponse.

Lung transplantation and survival in children with cystic fibrosis

BACKGROUND

The effects of lung transplantation on the survival and quality of life in children with cystic fibrosis are uncertain.

METHODS

We used data from the U.S. Cystic Fibrosis Foundation Patient Registry and from the Organ Procurement and Transplantation Network to identify children with cystic fibrosis who were on the waiting list for lung transplantation during the period from 1992 through 2002. We performed proportional-hazards survival modeling, using multiple clinically relevant covariates that were available before the children were on the waiting list and the interactions of these covariates with lung transplantation as a time-dependent covariate. The data were insufficient in quality and quantity for a retrospective quality-of-life analysis.

RESULTS

A total of 248 of the 514 children on the waiting list underwent lung transplantation in the United States during the period from 1992 through 2002. Proportional-hazards modeling identified four variables besides transplantation that were associated with changes in survival. Burkholderia cepacia infection was associated with a trend toward decreased survival, regardless of whether the patient underwent transplantation [corrected]. A diagnosis of diabetes before the patient was placed on the waiting list decreased survival while the patient was on the waiting list but did not decrease survival after transplantation, whereas older age did not affect waiting-list survival but decreased post-transplantation survival. Staphylococcus aureus infection increased waiting-list survival but decreased post-transplantation survival. Using age, diabetes status, and S. aureus infection status as covariates, we estimated the effect of transplantation on survival for each patient group, expressed as a hazard factor of less than 1 for a benefit and more than 1 for a risk of harm. Five patients had a significant estimated benefit, 283 patients had a significant risk of harm, 102 patients had an insignificant benefit, and 124 patients had an insignificant risk of harm associated with lung transplantation [corrected].

CONCLUSIONS

Our analyses estimated clearly improved survival for only 5 of 514 patients on the waiting list for lung transplantation. Prolongation of life by means of lung transplantation should not be expected in children with cystic fibrosis. A prospective, randomized trial is needed to clarify whether and when patients derive a survival and quality-of-life benefit from lung transplantation.

[The cemented MS-30 stem. A multi-surgeon series of 333 consecutive cases]

INTRODUCTION

So far there is only one peer-reviewed long-term publication from the inventors' clinic for the MS-30 stem.

MATERIAL AND METHODS

In a retrospective study we followed the first 333 consecutive MS-30 stems. All patients with 5- to 11-year follow-up were clinically and radiographically evaluated. At the time of implantation the criteria of modern cementing techniques were not implemented. Clinical evaluation was done using the scores of Harris and Merle d'Aubigné and Postel. Radiographic evaluation included quality of the cement mantle (true lateral radiographs taken under fluoroscopy), stem subsidence, loosening signs, and the risk for pending failure.

RESULTS

At follow-up 12 hips had undergone femoral revision: 3 for aseptic loosening, 6 for infection, 1 for periprosthetic fracture, and 2 for recurrent dislocation. The overall survival for all reasons at 10 years was 96.1%; survival with aseptic loosening as an end point was 99.0%. The median Harris Hip Score at follow-up was 80 (26-100) points. Radiological evaluation revealed a thin cement mantle (<2 mm) in approximately 2/3, predominantly on the lateral views (Gruen zones 8/9). One-third of all reviewed prostheses were considered at risk for pending failure, which strongly correlated with the initial quality of the cement mantle.

CONCLUSION

Midterm results with the MS-30 stem are encouraging and an even better long-term outcome can be expected with a better cement technique.

Mueller reinforcement rings in acetabular revision: outcome in 164 hips followed for 2-17 years

BACKGROUND

In revision hip arthroplasty, cages are commonly used for acetabular reconstruction in cases with loss of bone stock. It is important to follow this patient group closely, in order to better understand failure mechanisms and the chance of long-term success.

PATIENTS AND METHODS

We followed our first 164 acetabular revisions with the Mueller reinforcement ring (ARR) in 164 patients, with an average follow-up period of 6 (2-17) years. Mean age at surgery was 69 (29-92) years. 39 patients died (39 hips) during follow-up, but only 3 patients (3 hips) were lost to follow-up.

RESULTS

In the observation period, 13 of the hips had to undergo acetabular re-revision for aseptic and septic loosening. Overall survival at 5 years was 95% (CI: 89%-98%) and 90% (CI: 76%-95%) at 8 years using acetabular re-revision or implant removal for all reasons as endpoint. In addition, mechanical and clinical failure was seen in 2 cases. The mean Harris hip score was 70 points, whilst the Merle d'Aubigné score averaged 7 points. Radiolucent lines according to DeLee and Charnley were observed twice in zone I, 6 times in zone II and 14 times in zone III.

INTERPRETATION

We found that mid- to long-term survival of the ARR is acceptable. However, failure of the implant due to allograft collapse/resorption or deep infection, and also poor clinical outcome, remain major concerns in acetabular revision arthroplasty. This should be recognized when advising patients.

Nonresponse bias in a follow-up study of 19-year-old adolescents born as preterm infants

OBJECTIVE

To assess the effect of demographic and neonatal risk factors and outcome at the last available assessment on the probability of full responders, postal responders (those who only responded to the mailed questionnaire), or nonresponders in a follow-up study of 19-year-old adolescents who were born as preterm infants.

DESIGN

The 19-year follow-up program was part of a large ongoing collaborative study in The Netherlands on the long-term effect of prematurity and dysmaturity on various medical, psychological, and social parameters. In the original cohort, 1338 infants (94%) with a gestational age of < 32 weeks and/or a birth weight of < 1500 g were enrolled. Neonatal mortality was 23% (n = 312), and another 67 children had died between the ages of 28 days and 19 years, leaving 959 survivors (72% of the original cohort) for follow-up at the present assessment. To study the effect of nonresponse, we divided the 959 survivors into 3 groups: full responders (596 [62.1%]), postal responders (109 [11.4%]), and nonresponders (254 [26.5%]). In the 3 groups we compared demographic and neonatal data, as well as outcome at the last available assessment.

RESULTS

The odds ratios (ORs) for male versus female for the probabilities of nonresponse and postal response were statistically significant: 2.7 (95% CI: 1.9-3.9) and 1.6 (95% CI: 1.0-2.5), respectively. The same holds for the ORs for non-Dutch versus Dutch and low versus high maternal education for nonresponse: 2.0 (95% CI: 1.3-3.2) and 3.7 (95% CI: 2.0-6.7), respectively. Special education and severe handicap showed a statistically significant influence on nonresponse (OR: 1.6; 95% CI: 1.1-2.4 and OR: 2.6; 95% CI: 1.3-5.2) and postal response (OR: 2.0; 95% CI: 1.2-3.3 and OR: 4.4; 95% CI: 2.0-9.9), respectively. At the age of 19 years, primary school and special education were found significantly more frequent in the postal responders than in the full-response group (20% and 21% vs 6% and 12%). The full responders, on the other hand, were higher educated than were the postal responders.

CONCLUSIONS

In this follow-up study at the age of 19 years, boys, non-Dutch adolescents, and low maternal education were overrepresented in the nonresponse and postal-response groups. Nonresponse decreased the proportion of infants with adverse outcome in assessed children. To be able to present reliable results for the total group of survivors in long-term follow-up studies, the nonresponse bias needs to be quantified. Therefore, it is evident that more research using statistical methods such as imputation of missing data is needed.

Outcome of very preterm birth: children reviewed with ease at 2 years differ from those followed up with difficulty

AIM

To determine whether those most easily reviewed in a population prevalence study differ from those followed up only with difficulty.

METHODS

All babies born before 32 weeks of gestation in the North of England in 1983, 1990, and 1991 were traced, and all the survivors assessed at two years by one of two independent clinicians.

RESULTS

818 of the 1138 live born babies survived to discharge. There was some non-significant, excess disability in the 5% of long term survivors who were difficult to trace because of social mobility, but eight times as much severe disability in the 1% (9/796) in care and in the 5% (38/796) whose parents initially failed to keep a series of home or hospital appointments for interview, and five times as much emergent disability in the 2.7% (22/818) who died after discharge but before their second birthday. Had the babies who were seen without difficulty been considered representative of all the babies surviving to discharge, the reported disability rate would have been two thirds what it really was (6.9% instead of 11.0%).

CONCLUSIONS

Population prevalence studies that ignore those who seem reluctant to cooperate risk serious ascertainment bias.