Andrew R. Lockman, MD

ABSTRACT

BACKGROUND: About 10% of people in the United States develop at least 1 symptomatic kidney stone during their lives. The recurrence rate after 10 years is at least 50%. Many physicians recommend a low-calcium diet in patients with calcium oxalate stones to prevent recurrence. Recent studies suggest that a low-calcium diet may not be effective and that intake of animal protein and salt may influence renal calcium excretion. This study compares the traditional low-calcium diet with a diet that is low in animal protein and salt.

POPULATION STUDIED: This study enrolled 120 men with idiopathic hypercalciuria (urinary calcium excretion of more than 300 mg per day on an unrestricted diet) who had been referred to a nephrology clinic in Parma, Italy, and who had had at least 2 episodes of symptomatic renal stones. Reasons for exclusion included previous visits to any “stone disease center” and conditions associated with calcium stones, such as hyperparathyroidism or inflammatory bowel disease.

STUDY DESIGN AND VALIDITY: The investigators randomly assigned subjects, using concealed allocation, to 1 of 2 diets in this randomized controlled study. The low-calcium diet limited calcium intake to about 400 mg per day. The other diet, which included about 1200 mg per day of calcium, limited sodium chloride to about 3000 mg and animal protein to 93 g (15% of total calories). Both groups were advised to limit intake of high-oxalate foods and encouraged to drink 2 liters of water per day in cold weather and 3 liters in warm weather. Subjects were allowed moderate consumption of beer, wine, coffee, and sodas. (Detailed dietary instructions are available to New England Journal of Medicine subscribers in the supplement to the publication at www.nejm.org.) The study followed the patients for 5 years or until they developed clinical or radiologic evidence of a renal stone. Annual x-ray and ultrasound studies identified asymptomatic stone recurrences.

OUTCOMES MEASURED: The primary outcome was the time to development of the first recurrence of a renal stone, whether or not it was clinically evident. Other outcomes included changes in calcium and oxalate excretion and calcium oxalate saturation in the urine.

RESULTS: After 5 years, the low-protein, low-sodium diet led to fewer recurrences (20% compared with 38% in the low-calcium group, relative risk 0.49, number needed to treat with diet for 5 years = 5.5). The risk of recurrence in the low-calcium group was similar to the 35% to 40% expected in the absence of any intervention. The disease-oriented changes in urine characteristics were predictable: urinary calcium decreased in both groups, but oxalate secretion increased in the low-calcium group, causing greater calcium oxalate saturation.

ABSTRACT

BACKGROUND: About 10% of people in the United States develop at least 1 symptomatic kidney stone during their lives. The recurrence rate after 10 years is at least 50%. Many physicians recommend a low-calcium diet in patients with calcium oxalate stones to prevent recurrence. Recent studies suggest that a low-calcium diet may not be effective and that intake of animal protein and salt may influence renal calcium excretion. This study compares the traditional low-calcium diet with a diet that is low in animal protein and salt.

POPULATION STUDIED: This study enrolled 120 men with idiopathic hypercalciuria (urinary calcium excretion of more than 300 mg per day on an unrestricted diet) who had been referred to a nephrology clinic in Parma, Italy, and who had had at least 2 episodes of symptomatic renal stones. Reasons for exclusion included previous visits to any “stone disease center” and conditions associated with calcium stones, such as hyperparathyroidism or inflammatory bowel disease.

STUDY DESIGN AND VALIDITY: The investigators randomly assigned subjects, using concealed allocation, to 1 of 2 diets in this randomized controlled study. The low-calcium diet limited calcium intake to about 400 mg per day. The other diet, which included about 1200 mg per day of calcium, limited sodium chloride to about 3000 mg and animal protein to 93 g (15% of total calories). Both groups were advised to limit intake of high-oxalate foods and encouraged to drink 2 liters of water per day in cold weather and 3 liters in warm weather. Subjects were allowed moderate consumption of beer, wine, coffee, and sodas. (Detailed dietary instructions are available to New England Journal of Medicine subscribers in the supplement to the publication at www.nejm.org.) The study followed the patients for 5 years or until they developed clinical or radiologic evidence of a renal stone. Annual x-ray and ultrasound studies identified asymptomatic stone recurrences.

OUTCOMES MEASURED: The primary outcome was the time to development of the first recurrence of a renal stone, whether or not it was clinically evident. Other outcomes included changes in calcium and oxalate excretion and calcium oxalate saturation in the urine.

RESULTS: After 5 years, the low-protein, low-sodium diet led to fewer recurrences (20% compared with 38% in the low-calcium group, relative risk 0.49, number needed to treat with diet for 5 years = 5.5). The risk of recurrence in the low-calcium group was similar to the 35% to 40% expected in the absence of any intervention. The disease-oriented changes in urine characteristics were predictable: urinary calcium decreased in both groups, but oxalate secretion increased in the low-calcium group, causing greater calcium oxalate saturation.

ABSTRACT

BACKGROUND: About 10% of people in the United States develop at least 1 symptomatic kidney stone during their lives. The recurrence rate after 10 years is at least 50%. Many physicians recommend a low-calcium diet in patients with calcium oxalate stones to prevent recurrence. Recent studies suggest that a low-calcium diet may not be effective and that intake of animal protein and salt may influence renal calcium excretion. This study compares the traditional low-calcium diet with a diet that is low in animal protein and salt.

POPULATION STUDIED: This study enrolled 120 men with idiopathic hypercalciuria (urinary calcium excretion of more than 300 mg per day on an unrestricted diet) who had been referred to a nephrology clinic in Parma, Italy, and who had had at least 2 episodes of symptomatic renal stones. Reasons for exclusion included previous visits to any “stone disease center” and conditions associated with calcium stones, such as hyperparathyroidism or inflammatory bowel disease.

STUDY DESIGN AND VALIDITY: The investigators randomly assigned subjects, using concealed allocation, to 1 of 2 diets in this randomized controlled study. The low-calcium diet limited calcium intake to about 400 mg per day. The other diet, which included about 1200 mg per day of calcium, limited sodium chloride to about 3000 mg and animal protein to 93 g (15% of total calories). Both groups were advised to limit intake of high-oxalate foods and encouraged to drink 2 liters of water per day in cold weather and 3 liters in warm weather. Subjects were allowed moderate consumption of beer, wine, coffee, and sodas. (Detailed dietary instructions are available to New England Journal of Medicine subscribers in the supplement to the publication at www.nejm.org.) The study followed the patients for 5 years or until they developed clinical or radiologic evidence of a renal stone. Annual x-ray and ultrasound studies identified asymptomatic stone recurrences.

OUTCOMES MEASURED: The primary outcome was the time to development of the first recurrence of a renal stone, whether or not it was clinically evident. Other outcomes included changes in calcium and oxalate excretion and calcium oxalate saturation in the urine.

RESULTS: After 5 years, the low-protein, low-sodium diet led to fewer recurrences (20% compared with 38% in the low-calcium group, relative risk 0.49, number needed to treat with diet for 5 years = 5.5). The risk of recurrence in the low-calcium group was similar to the 35% to 40% expected in the absence of any intervention. The disease-oriented changes in urine characteristics were predictable: urinary calcium decreased in both groups, but oxalate secretion increased in the low-calcium group, causing greater calcium oxalate saturation.

BACKGROUND: Prostate cancer is the second leading cause of death due to cancer in men, but substantial controversy surrounds the role of PSA in screening asymptomatic patients. Although the test can help detect prostate cancer earlier, we currently lack evidence that this early detection will increase length or quality of life. The issues involved in the controversy include frequent false-positive results, potential for complications from treatment, and the frequency of slow-growing tumors that may never become clinically significant. In recognition of this complexity, the American Cancer Society and the American Urological Association revised their recommendations for men older than 50 years, calling for shared decision making in which the patient and physician discuss options and together make a decision that agrees with the patient’s individual health preferences. Of note, most other major organizations do not advocate routine PSA tests for screening. Previous research has shown that the way information about PSA testing is presented can influence the outcome of shared decision making. This study compared the effect of either a scripted discussion or videotape on men’s opinions about taking the PSA test.

POPULATION STUDIED: The investigators approached all men older than 50 years who were presenting for an annual preventive care evaluation at a large health maintenance organization (HMO). The participants (n=176) were sequentially assigned to 1 of 4 interventions: usual care, a discussion about risks and benefits of PSA, a shared decision-making video, or the video plus discussion. Baseline characteristics including age, education, marital status, ethnicity (more than 70% white), history of friend or family member with prostate cancer, and previous PSA testing did not differ among groups. Approximately 40% of those contacted to participate in 1 of the 3 interventions refused, but recruitment rates did not differ among the intervention groups.

STUDY DESIGN AND VALIDITY: The investigators used a nonrandomized unblinded 2x2 factorial comparison of the discussion and video formats that yielded the 4 groups described above. A previous study evaluated and described the 25-minute video, and the lecture-format discussion closely followed the content of the video.

OUTCOMES MEASURED: Measured responses in all groups included whether they wanted PSA testing, their level of confidence in their decision, and levels of knowledge and concern about prostate cancer. Those in the intervention groups also rated the amount, clarity, and perceived balance and fairness of the presentations. The study did not measure the actual incidence of subsequent PSA testing.

RESULTS: Almost all (97%) in the usual care group opted for testing. Discussion decreased the testing rate to 82% (P <.05), and members of the video (63%) and video/discussion (50%) groups chose testing even less frequently (P <.05 for difference between the discussion-only and either video group). All of the interventions (other than usual care) significantly increased knowledge about prostate cancer (3.4-3.9 correct responses to 5 questions vs 1.6, P <.001) and decreased confidence in the decision regarding PSA. Subjects in the usual care group expressed more concern about prostate cancer than those in the intervention groups. Less than 1% of subjects felt negative about participating in the interventions. Eighty-two percent considered the presentation balanced; 8% felt it was slanted in favor of screening; and 11% felt it was slanted against having PSA testing.

BACKGROUND: Prostate cancer is the second leading cause of death due to cancer in men, but substantial controversy surrounds the role of PSA in screening asymptomatic patients. Although the test can help detect prostate cancer earlier, we currently lack evidence that this early detection will increase length or quality of life. The issues involved in the controversy include frequent false-positive results, potential for complications from treatment, and the frequency of slow-growing tumors that may never become clinically significant. In recognition of this complexity, the American Cancer Society and the American Urological Association revised their recommendations for men older than 50 years, calling for shared decision making in which the patient and physician discuss options and together make a decision that agrees with the patient’s individual health preferences. Of note, most other major organizations do not advocate routine PSA tests for screening. Previous research has shown that the way information about PSA testing is presented can influence the outcome of shared decision making. This study compared the effect of either a scripted discussion or videotape on men’s opinions about taking the PSA test.

POPULATION STUDIED: The investigators approached all men older than 50 years who were presenting for an annual preventive care evaluation at a large health maintenance organization (HMO). The participants (n=176) were sequentially assigned to 1 of 4 interventions: usual care, a discussion about risks and benefits of PSA, a shared decision-making video, or the video plus discussion. Baseline characteristics including age, education, marital status, ethnicity (more than 70% white), history of friend or family member with prostate cancer, and previous PSA testing did not differ among groups. Approximately 40% of those contacted to participate in 1 of the 3 interventions refused, but recruitment rates did not differ among the intervention groups.

STUDY DESIGN AND VALIDITY: The investigators used a nonrandomized unblinded 2x2 factorial comparison of the discussion and video formats that yielded the 4 groups described above. A previous study evaluated and described the 25-minute video, and the lecture-format discussion closely followed the content of the video.

OUTCOMES MEASURED: Measured responses in all groups included whether they wanted PSA testing, their level of confidence in their decision, and levels of knowledge and concern about prostate cancer. Those in the intervention groups also rated the amount, clarity, and perceived balance and fairness of the presentations. The study did not measure the actual incidence of subsequent PSA testing.

RESULTS: Almost all (97%) in the usual care group opted for testing. Discussion decreased the testing rate to 82% (P <.05), and members of the video (63%) and video/discussion (50%) groups chose testing even less frequently (P <.05 for difference between the discussion-only and either video group). All of the interventions (other than usual care) significantly increased knowledge about prostate cancer (3.4-3.9 correct responses to 5 questions vs 1.6, P <.001) and decreased confidence in the decision regarding PSA. Subjects in the usual care group expressed more concern about prostate cancer than those in the intervention groups. Less than 1% of subjects felt negative about participating in the interventions. Eighty-two percent considered the presentation balanced; 8% felt it was slanted in favor of screening; and 11% felt it was slanted against having PSA testing.

BACKGROUND: Prostate cancer is the second leading cause of death due to cancer in men, but substantial controversy surrounds the role of PSA in screening asymptomatic patients. Although the test can help detect prostate cancer earlier, we currently lack evidence that this early detection will increase length or quality of life. The issues involved in the controversy include frequent false-positive results, potential for complications from treatment, and the frequency of slow-growing tumors that may never become clinically significant. In recognition of this complexity, the American Cancer Society and the American Urological Association revised their recommendations for men older than 50 years, calling for shared decision making in which the patient and physician discuss options and together make a decision that agrees with the patient’s individual health preferences. Of note, most other major organizations do not advocate routine PSA tests for screening. Previous research has shown that the way information about PSA testing is presented can influence the outcome of shared decision making. This study compared the effect of either a scripted discussion or videotape on men’s opinions about taking the PSA test.

POPULATION STUDIED: The investigators approached all men older than 50 years who were presenting for an annual preventive care evaluation at a large health maintenance organization (HMO). The participants (n=176) were sequentially assigned to 1 of 4 interventions: usual care, a discussion about risks and benefits of PSA, a shared decision-making video, or the video plus discussion. Baseline characteristics including age, education, marital status, ethnicity (more than 70% white), history of friend or family member with prostate cancer, and previous PSA testing did not differ among groups. Approximately 40% of those contacted to participate in 1 of the 3 interventions refused, but recruitment rates did not differ among the intervention groups.

STUDY DESIGN AND VALIDITY: The investigators used a nonrandomized unblinded 2x2 factorial comparison of the discussion and video formats that yielded the 4 groups described above. A previous study evaluated and described the 25-minute video, and the lecture-format discussion closely followed the content of the video.

OUTCOMES MEASURED: Measured responses in all groups included whether they wanted PSA testing, their level of confidence in their decision, and levels of knowledge and concern about prostate cancer. Those in the intervention groups also rated the amount, clarity, and perceived balance and fairness of the presentations. The study did not measure the actual incidence of subsequent PSA testing.

RESULTS: Almost all (97%) in the usual care group opted for testing. Discussion decreased the testing rate to 82% (P <.05), and members of the video (63%) and video/discussion (50%) groups chose testing even less frequently (P <.05 for difference between the discussion-only and either video group). All of the interventions (other than usual care) significantly increased knowledge about prostate cancer (3.4-3.9 correct responses to 5 questions vs 1.6, P <.001) and decreased confidence in the decision regarding PSA. Subjects in the usual care group expressed more concern about prostate cancer than those in the intervention groups. Less than 1% of subjects felt negative about participating in the interventions. Eighty-two percent considered the presentation balanced; 8% felt it was slanted in favor of screening; and 11% felt it was slanted against having PSA testing.