The impact of waiting time on health gains from surgery: Evidence from a national patient reported outcomes dataset Running title

3.2Valuation of the health losses

Following estimation of the impact of waiting time on outcomes at individual level, we estimate the value of an additional week of waiting for the entire population of treated patients. To do so, we have to assume a period of time over which the health-related quality-of-life loss will be experienced. We assume that the health loss observed 3 or 6 months post-surgery is permanent and estimate its duration by applying gender and year-of-age specific life expectancy estimates taken from the 2008-2010 Interim Life Tables from the Office for National Statistics (Office for National Statistics, 2011) to the treated population. We discount future quality-adjusted life years using the annual rate of 3.5% specified by NICE in their reference case (NICE, 2008). We apply the estimates of waiting times on the EQ-5D index to calculate the change in quality-adjusted life expectancy for an additional week of waiting per patient and value this change using the NICE estimate of £20,000 for life year (NICE, 2013).

4Results

4.1Descriptive statistics

Table 1 presents the summary statistics. The average age of patients undergoing hip-replacement or knee-replacement surgery was approximately 69 years, which is higher than the average age for varicose patients (53 years) or for hernia repair patients (62 years). Approximately 60 % of hip and knee patients were women. Most varicose vein patients were women (65%), while most hernia repair patients were men. The average patient in each surgical category lives in an area where 12-14% of the population receive state benefits on the grounds of low income.

Of all patients admitted to hospital for elective hip replacement, 10% have previously had hip replacement surgery. Seven percent of knee patients had previously been admitted for knee replacement surgery, and 4% of the varicose vein patients had previous surgery for the same condition. Surprisingly, we find that 87% of patients treated for hernia repair have had a previous surgery for that. The three most prevalent health problems among hip, knee and hernia patients were arthritis, high blood pressure, and heart disease. Among varicose vein patients the three health conditions are high blood pressure, arthritis, and problems with circulation. Two-thirds of hip patients and half of knee patients have had symptoms for 1-5 years. Most patients undergoing varicose veins or hernia surgery had problems for less than one year. Approximately 60% of hip or knee replacement patients have some type of disability, while approximately 10% of varicose vein or hernia repair patients suffer from disability.

A half of hip and a third of knee patients reported some problems with self-care, while most patients with vein or hernia problems did not have any issues with self-care. A third of hip and knee patients had moderate anxiety/depression, while majority of patients with vein or hernia problems suffered from anxiety/depression. Almost all hip or knee patients had some problems with mobility, while only a fifth of vein or hernia patients have mobility problems. The majority of hip or knee patients experienced some problems with performing their usual activities. Only a fifth of vein and hernia patients reported some problems with their usual activities.

Patients, on average, waited 78 days (10.8 weeks) for hip replacement, 79 days (10.9 weeks) for knee repair, 70 days (9.8 weeks) for varicose vein surgery, 61 days (8.3 week) for hernia repair. We observe large gains in unadjusted health for hip and knee patients as measured by generic and condition-specific metrics. For varicose veins and hernia repair patients we find small changes in the EQ5D score, no changes in the EQ-VAS score, and a decline in the AVV score.

Approximately 85% of hip patients, 87% of knee patients, 91% of varicose vein patients, and 95% of hernia patients reported that their problems were better following the surgery. Approximately 91% of hip patients assessed the results of the surgery as “good”, “very good”, or “excellent”. The respective percentages for knee, vein, and hernia patients are 82, 87, and 92. 80% of hip patients ranked their post-surgery health as good, very good, or excellent. 73, 90, and 86% are the respective numbers for knee, vein, and hernia patients.

4.2Regression Results

Table 2 reports the results from ordinary least squares (OLS) regression of waiting times on time-invariant and time-defined variables. Women waited longer than men for knee replacement surgery. We find that older patients waited longer for hip replacement surgery, but the effect is non-linear. No age effect is observed in waiting times for the other three types of surgery. Living alone is associated with longer waiting times for varicose vein surgery, but not for any of the other treatments. Patients who had had the symptoms for a longer period of time waited longer for hip and knee surgery. Patients who had previously had varicose vein surgery waited longer for treatment, while patients with previous hernia surgery waited a shorter period. Hip patients who did not have a disability experienced longer waits.

There is no consistent pattern in the effects of other pre-existing health conditions on waiting times. Lung disease, liver disease, and arthritis were associated with longer waits for hip replacement. Heart disease, stroke, and kidney disease were associated with longer waits for knee replacement surgery, while depression was associated with shorter waiting times. None of the pre-existing conditions affected waiting times for varicose vein surgery. Patients with heart disease and high blood pressure waited longer for hernia repair surgery.

Table 3 reports the estimated coefficients on the waiting times variables from the OLS regressions of the post-surgery PROMs. To obtain coefficients on similar scales across measures, we multiplied the EQ-5D index scores by 100 and rescaled the disease-specific scores to run from zero (worst state) to 100 (best state). The waiting time between the decision to admit and admission for treatment had a negative and statistically significant effect on all post-surgery measures of health for hip and knee replacement. An additional week of waiting reduced the EQ-VAS, EQ-5D, and OHS scores of hip replacement patients by 0.06%, 0.05%, and 0.1%, respectively. In the case of knee replacement, an additional week on the waiting list reduced the EQ-VAS, EQ-5D, and OKS scores by 0.06%, 0.06%, and 0.04%. The effects of waiting time on outcomes for varicose vein and hernia repair surgery were much smaller in magnitude and statistically insignificant.

Table 4 shows the estimates for the remaining patient specific covariates. They include patient gender and age, and age polynomials of second and third degree. We controlled for pre-surgery health scores and generic health measures measured prior to surgery. The coefficient estimates on the variables “general health”, “self-care”, “mobility”, “activity”, “pain/discomfort”, “anxiety” should be interpreted relative to the excluded category. A similar interpretation should be applied to the “living arrangements” and “length of symptoms” variables. We have also controlled for different pre-existing health conditions. Patients with higher health scores at the date of completion of the pre-surgery questionnaire had higher post-surgery scores. Two dimensions of the EQ5D index, self-care and anxiety, had negative and significant impacts on post-surgery scores across all four categories of patients. We find that pre-surgery problems with mobility impacted on post-surgery health for varicose vein and hernia patients.

Several pre-existing health problems were found to be negatively and significantly associated with post-surgery scores for all three outcomes. For hip patients, these conditions were heart disease, problems with circulation, diabetes, depression, and arthritis. Heart disease, circulation, and depression impacted negatively on the post-surgery health of knee patients. For varicose vein patients, these conditions were heart disease, circulation, depression, and arthritis. The post-surgery health of hernia patients was negatively affected by the presence of circulation problems and arthritis.

Hip and knee patients who had had previous surgery reported substantially lower post-surgery health. The results for varicose vein patients show lower EQ5D and EQ-VAS scores, and slightly higher AVV scores. The EQ5D and EQ-VAS scores were higher for hernia patients who had had previous surgery.

Hip patients from income-deprived areas reported lower EQ5D and Oxford Hip Scores. Hernia patients from income deprived areas had lower EQ5D and EQ-VAS scores.

Table 5 presents the marginal effects of waiting times on the three categorical variables measuring patient satisfaction with, and perception of the benefits of, their surgery. Across all types of surgery we find that longer waits decreased the probability that patients assessed the state of their post-surgery problems as “much better” compared to before. The probabilities associated with the remaining categories - “a little better”, “about the same”, “a little worse”, “much worse” - increase. The results are statistically significant for hip, knee, and varicose vein patients, but not for patients who underwent hernia repair surgery.

Longer waits decreased the probability of reporting excellent results from hip surgery and increased the probability of perceiving the outcomes as “very good”, “good”,” fair”, or “poor”. We find that longer waits lowered the probability of reporting results from varicose vein surgery as “excellent” and “very good” and increased the probability of reporting the other categories. No statistically significant results were found for knee surgery and hernia repair.

We also find that longer waits decreased the probability of patients reporting excellent or very good results from hip, knee, or varicose vein surgery. They were associated with higher probabilities of self-reporting health as “good”,” fair”, or “poor”, though the effects are not statistically significant. For hernia patients, we find that longer waiting times were associated with increased probabilities of reporting post-surgery health to be excellent or very good and decreased probabilities of reporting health to be good, fair, or poor. However, these marginal effects are not statistically significant.