Most research on obesity is derived from young and middle-aged patients. There is limited data regarding the prognostic importance of overweight and obesity in the elderly. Surprisingly, overweight and mild obesity do not seem to be associated with any significant increase in cardiovascular mortality in individuals 65 years of age or older, as compared with younger cohorts. The data, in fact, suggest that individuals 65 and older may require a higher optimum body mass index (BMI) than the ideal weight currently defined in federal guidelines for all individuals as a BMI between 18.7 and 24.9 [6]. Longitudinal studies looking at the effects of aging on body composition suggest that aging is associated with a decrease in lean muscle mass and increase in fat mass regardless of changes in overall body weight [7, 8]. This loss of muscle mass that occurs with aging is a process called sarcopenia, which may not be as clearly identified by BMI alone [9]. In addition, the natural loss of height seen with increases in age is more significant in females and may also arbitrarily elevate BMI [10]. Several studies have shown that the excess mortality associated with obesity actually declines with age [11]. In addition, there have been conflicting data from observational studies associating weight loss with increased mortality in the elderly [12–14]; however, the far majority of studies do not make the distinction between intentional and unintentional weight loss, the latter of which may be a reflection of other confounding conditions such as cancer, failure to thrive, or worsening of chronic comorbid conditions, which would increase mortality risk and may explain some of the discrepancy. A recent RCT, however, found no significant difference in all-cause mortality between older (mean age 65.5 ± 4.5 years) overweight and obese (mean BMI 31.1 ± 2.3) adults who were randomized to intentional dietary weight loss (mean weight loss of 4.4 kg) over a 12-year period [15]. Given the increased incidence of sarcopenic obesity in the elderly population, future prospective studies will need to continue to separate and make the clear distinction between intentional and unintentional weight loss when determining the risk of mortality.

Therefore, until age-specific recommendations are made, elderly patients who are being considered for weight reduction surgery should continue to meet whatever the currently accepted weight criteria or other criteria for defining morbid obesity and clinically severe obesity exist, whether this be the NIH consensus guidelines or other new emerging guidelines. There are also very few studies involving medical weight loss in the elderly. Most studies on supervised diets or medications have been performed in younger patients. Thus, it is recommended that elderly patients have attempted a serious effort at documented medical weight loss before undergoing surgical treatment, particularly since moderate dietary reduction and exercise have been shown to be safe in preserving lean muscle mass. Studies looking at physical activity in the elderly have shown that increased physical activity is associated with decreased mortality. In an observational study by Lee et al., it was shown that there was a higher all-cause and cardiovascular mortality in lean unfit subject than in obese fit subjects, once again emphasizing the importance of physical activity and muscle mass preservation over the amount of body fat alone, in predicting the risk of mortality [16].

Due to the lack of any uniform consensus, the onus of patient selection falls on the bariatric surgeon. Chronologic age alone is a poor predictor of the outcome as the elderly patient may have limited ability for recovery. Preoperative evaluation necessitates further investigations compared to the general population [17]. Emphasis should be placed on the evaluation of the functional status of the individual. The impact of age on surgical risk arises from a decrease in vital organ function. This is attributable to the normal aging process in conjunction with any preexisting disease, resulting in a decreased ability to respond optimally to operative stress [18]. The decline in physiologic capacity to respond to surgical stress, independent of specific individual organ system dysfunction, is referred to as frailty [17].

Frailty takes into account multiple factors that may place the geriatric patient at a distinct physiologic disadvantage. It is important to note that a patient does not simply fall into one of the two categories: for an elderly with or without frailty rather, one needs to carry out a quantitative analysis for measurement of frailty index [19]. There are multiple tools that can be used for preoperative frailty assessment, one of which is the Katz ADL score which examines the patients’ level of independence on daily activities. The patient is given a point for each of six activities: grooming, bathing, feeding, dressing, toiletry, and dressing [20]. In addition to independence in daily life and medical comorbidites, an assessment for mobility, nutritional, and cognitive status (the mini-mental test) has been recommended for preoperative evaluation of patients in general surgery literature [21].

In addition to age, one should consider other independent patient risk characteristics associated with increased morbidity and mortality, which include male gender [22]. Patients should be stratified into a high- or low-risk category based on the number of associated diseases. The literature suggests that the preoperative condition of the patient is more important than intraoperative events in predicting adverse outcomes after surgery. A dramatic increase in perioperative deaths has been seen in elderly patients with multisystem disease. Premorbid conditions that may increase perioperative risk include congestive heart failure (CHF) and coronary artery disease [23]. Nguyen et al. published data from the National Inpatient Sample which reviewed >300,000 inpatients undergoing lap and open gastric bypass over a 3-year period (2006–2008) and identified peripheral vascular disease and chronic renal failure as comorbid conditions associated with increased risk of inpatient mortality. The goal of any bariatric operation should be to improve the quality of postoperative life, or at minimum, not impair it. Therefore, preoperative optimization of the elderly patient’s overall condition, without undue delay in surgery, is advocated.

There are several normal age-related physiologic changes that may or may not have any overt clinical findings. These age-related changes result in altered end organ function, most importantly cardiac, pulmonary, and renal function. Cardiac output can be decreased from a blunted response to catecholamines, which can lead to increased ectopy that may not be seen in the resting state. Hypertrophy of the left ventricular mass can add to any underlying diastolic dysfunction already present. It may be prudent in elderly patients to evaluate the functional cardiac status under stressed conditions (using a treadmill stress test or a Persantine thallium scan), even in the presence of a normal electrocardiogram. A transthoracic echocardiogram should also be considered in any patient with history of CHF.

The changes in the respiratory system include decreased chest wall compliance, decreased lung volumes, and decreased strength of the respiratory musculature, resulting in an overall decline of pulmonary function. Elderly patients, therefore, may be more susceptible to postoperative respiratory complications. Pulmonary function tests are not normally required in the workup of a routine bariatric candidate but may be informative, particularly if there is a question regarding pulmonary reserve in a patient with baseline chronic lung disease (previous episodes of pneumonia, long smoking history, pulmonary embolus, asthma) or obesity hypoventilation syndrome.

Normal renal changes include decreased renal blood flow with resultant decreased glomerular filtration rate and decreased creatinine clearance. Patients who present with marginal renal function should have close attention to their perioperative fluid status. Gentle hydration without large volume shifts is generally better tolerated. Any potentially nephrotoxic drugs should be discontinued prior to surgery [18].

One postoperative complication that is relatively unique to the elderly population is delirium. Delirium is defined as a “clinical syndrome in which there is an acute disruption of attention and cognition” [24]. Delirium has been associated most commonly with cardiac and orthopedic procedures but has been reported in all types of surgery. When delirium occurs postoperatively, it has been associated with increased morbidity and mortality [25]. Preoperative risk factors include age, history of or current alcohol abuse, history of depression, dementia, and the presence of any metabolic derangements [25]. Recent studies have suggested preoperative variables associated with an increased risk of postoperative delirium to include: age, low serum albumin, impaired functional status, medical comorbidities, and presence of dementia. The strongest single risk factor for the development of delirium was preexisting dementia [26]. Screening for these risk factors and correction preoperatively as necessary should be attempted.

Immobility is a problem associated with morbid obesity that can become aggravated in elderly patients. The incidence of degenerative joint disease increases with age, and many obese elderly patients may be denied corrective joint repair due to their excess weight. Their immobility, however, may limit their ability to lose weight through more conservative measures such as diet and exercise, leaving surgery as one of the few options for effective treatment. Immobility can also result in wound care issues, with the formation of decubitus ulcers. Elderly bariatric patients requiring long-term intensive care are at high risk for the development of such ulcers. For the uncomplicated postoperative patient, early ambulation is essential, which in the elderly may require assistance from physiotherapists or the nursing staff. In addition, consideration for extended DVT chemoprophylaxis and/or placement in acute rehab postoperatively should be discussed as part of informed consent and preoperative planning for patients with poor mobility.

There are several studies in the literature that suggest an increased risk of mortality in the elderly after surgery. In general, most of these studies, however, have small sample size, include patients in their eighth and ninth decades of life, as well as those undergoing cancer operations, cardiac procedures, or semi-emergent operations [27–30]. It is on the basis of such a wide range of operations that much of our early outcomes data on the elderly had been gathered. Although we are still gaining insight on the safest way to manage elderly patients, certain trends have been established. Emergency surgery is associated with higher morbidity and mortality in all age groups, but particularly in the elderly. Elderly patients often present with more advanced disease, forcing surgical therapy once complications have already occurred. Elderly patients have a higher percentage of preexisting comorbid conditions, making them less likely to tolerate complications, if they occur; therefore, prevention remains essential [23].

Historically, many bariatric centers refused surgery to patients over 50. In 1977, Printen et al. [31] reported a greater than twofold increase in mortality after gastric bypass in patients older than 50 compared with those younger than 50 (8 % vs. 2.8 %). This, however, was an evaluation of only 36 patients during a time when the overall mortality for gastric bypass was significantly higher than what is seen today. In contrast, MacGregor and Rand [32] in 1993 did not find a statistical difference in mortality (1.1 % vs. 0.6 %) in those patients aged 50 or older as compared with younger patients undergoing a variety of obesity operations. Similar findings were shown by Murr et al. [33] in 1995. A later study by Livingston et al. [34] suggested that increasing age was not associated with increased morbidity after gastric bypass. However, if a complication were to occur in this population, the incidence of mortality associated with an adverse event was threefold in older patients, reinforcing the concept that elderly patients may have less physiologic reserve than younger patients to overcome an adverse event [35].